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general description the max1359b smart data-acquisition systems (das) isbased on a 16-bit, sigma-delta analog-to-digital converter (adc) and system- support functionality for a micro- processor (?)-based system. this device integratesan adc, dac, two operational amplifiers, internal 1.25v/2.048v/2.5v selectable reference, temperature sensors, analog switches, a 32khz oscillator, a real- time clock (rtc) with alarm, a high-frequency-locked loop (fll) clock, four user-programmable i/os, an interrupt generator, and 1.8v and 2.7v voltage monitors in a single chip. the max1359b has dual 10:1 differential input multi- plexers (muxes) that accept signal levels from 0 to av dd . an on-chip 1x to 8x programmable-gain amplifi- er (pga) measures low-level signals and reduces exter-nal circuitry required. the max1359b operates from a single +1.8v to +3.6v supply and consumes only 1.4ma in normal mode and only 6.1? in sleep mode. the serial interface is compatible with either spi/qspi or microwire, and is used to power up, configure, and check the status of all functional blocks. the max1359b is available in a space-saving 40-pin tqfn package and is specified over the commercial (0 c to +70 c) and the extended (-40 c to +85 c) tem- perature ranges. applications battery-powered and portable deviceselectrochemical and optical sensors medical instruments industrial control data-acquisition systems features ? +1.8v to +3.6v single-supply operation ? multichannel 16-bit sigma-delta adc 10sps to 512sps programmable conversion rate self and system offset and gain calibration pga with gains of 1, 2, 4, or 8 unipolar and bipolar modes 10-input differential multiplexer ? 10-bit force-sense dac ? uncommitted op amps ? dual spdt analog switches ? 1.25v, 2.048v, or 2.5v selectable voltage reference ? internal charge pump ? system support real time clock and alarm register internal/external temperature sensor internal oscillator with clock output user-programmable i/o and interrupt generator v dd monitors ? spi/qspi/microwire, 4-wire serial interface ? space-saving (6mm x 6mm x 0.8mm) 40-pin tqfn package max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ _____________ maxim integrated products 1 ordering information 19-3710; rev 2; 8/10 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part temp range pin-package max1359betl+ -40 c to +85 c 40 tqfn-ep** max1359bctl+ 0 c to +70 c 40 tqfn-ep** spi/qspi are trademarks of motorola, inc. microwire is a trademark of national semiconductor corp. ** ep = exposed pad. + denotes a lead(pb)-free/rohs-compliant package. pin configuration 40 39 38 37 36 35 34 33 32 31 21 22 23 24 25 26 27 28 29 30 cpout in1+ in1- out2in2+ swa fba outa agnd in2- ain2 ain1 ref reg av dd cf- cf+ dv dd dgnd upio1 11 12 13 14 15 16 17 18 19 20 10 9 8 7 6 5 4 3 2 1 clk upio2 upio3 upio4 dout sclk din int clk32k 32kout 32kin sno1 scm1 snc1 out1 snc2scm2 sno2 max1359b cs reset tqfn downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 2 __________________________________________________ _____________________________________ absolute maximum ratings electrical characteristics (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. av dd to agnd .........................................................-0.3v to +4v dv dd to dgnd.........................................................-0.3v to +4v av dd to dv dd ............................................................-4v to +4v agnd to dgnd.....................................................-0.3v to +0.3v clk32k to dgnd ....................................-0.3v to (dv dd + 0.3v) upio_ to dgnd........................................................-0.3v to +4v digital inputs to dgnd ............................................-0.3v to +4v analog inputs to agnd ...........................-0.3v to (av dd + 0.3v) digital output to dgnd........................-0.3v to (dv dd + 0.3v) analog outputs to agnd.........................-0.3v to (av dd + 0.3v) cpout........................................................(dv dd - 0.3v) to +4v continuous current into any pin.........................................50ma continuous power dissipation (t a = +70 c) 40-pin tqfn (derate 25.6mw/ c above +70 c) ....2051.3mw operating temperature range max1359betl.................................................-40 c to +85 c max1359bctl ...................................................0 c to +70 c junction temperature ......................................................+150? storage temperature range .............................-65 c to +150 c lead temperature (soldering, 10s) .................................+260 c parameter symbol conditions min typ max units adc dc accuracy noise-free resolution data rate = 10sps, pga gain = 2;data rate = 10sps to 60sps, pga gain = 1; no missing codes, table 1 (note 2) 16 bits conversion rate no missing codes, table 1 10 512 sps output noise no missing codes table 1 v rms integral nonlinearity inl unipolar mode, av dd = 3v, data rate = 40sps, pga gain = 1,t a = +25 c 0.004 %fsr uncalibrated 1.0 unipolar offset error or bipolarzero error (note 3) data rate = 10sps, pga gain = 1, calibrated 0.003 %fsr bipolar 2.0 unipolar offset-error or bipolarzero-error temperature drift (note 4) unipolar 10 ?/ c uncalibrated 0.6 gain error (notes 3, 5) data rate = 10sps, pga = 1, calibrated 0.003 % fsr gain-error temperaturecoefficient (notes 4, 6) 1.0 ppm/ c dc positive power-supplyrejection ratio psrr pga gain = 1, unipolar mode, measured by full-scale error with av dd = 1.8v to 3.6v 73 db adc analog inputs (ain1, ain2) dc input common-moderejection ratio cmrr pga gain = 1, unipolar mode 85 db downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ____________________________________ 3 electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units normal-mode 60hz rejectionratio data rate = 10sps or 60sps, pga gain = 1,unipolar mode (note 2) 100 db normal-mode 50hz rejectionratio data rate = 10sps or 50sps, pga gain = 1,unipolar mode (note 2) 100 db absolute input range agnd av dd v unipolar mode -0.05 / gain v ref / gain differential input range bipolar mode -v ref / gain v ref / gain v adc not in measurement mode, muxenabled, t a +55 c, inputs = +0.1v to (av dd - 0.1v) 1 dc input current (note 7) t a = +85 c 5 na input sampling capacitance c in 5p f input sampling rate f sample 21.84 khz external source impedance atinput see table 3 table 3 k force-sense dac (r l = 10k and c l = 200pf, fba = outa, unless otherwise noted) resolution guaranteed monotonic 10 bits differential nonlinearity dnl code 3d hex to 3ff hex 1 lsb integral nonlinearity inl code 3d hex to 3ff hex 4 lsb offset error reference to code 52 hex 20 mv offset-error tempco ?.4 ?/ c gain error excludes offset and voltage reference error 5 lsb gain-error tempco excludes offset and reference drift 1 ppm/ c input leakage current at swa/b swa/b switches open (notes 7, 8) 1n a t a = -40 c to +85 c 1n a t a = 0 c to +70 c 600 input leakage current at fba/b v fba/b = +0.3v to (av dd - 0.3v) (note 7) t a = 0 c to +50 c 400 pa dac output buffer leakagecurrent dac buffer disabled (note 7) 75 na input common-mode voltage at fba 0 av dd - 0.35 v line regulation av dd = +1.8v to +3.6v 40 175 ?/v load regulation i out = 2ma, c l = 1000pf (note 2) 0.5 ?/? output voltage range agnd av dd v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 4 __________________________________________________ _____________________________________ electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units output slew rate 52 hex to 3ff hex code swing rising orfalling, r l = 10k , c l = 100pf 40 v/ms output-voltage settling time 10% to 90% rising or falling to 0.5 lsb 65 ? f = 0.1hz to10hz 80 input voltage noise referred to fba excludesreference noise f = 10hz to10khz 200 ? p-p outa/b shorted to agnd 20 output short-circuit current outa/b shorted to av dd 15 ma input-output swa switchresistance between swa and outa, hfck enabled 150 swa switch turn-on/off time hfck enabled 100 ns power-on time excluding reference 18 ? external reference (ref) input voltage range agnd av dd v input resistance dac on, internal ref and adc off 2.5 m dc input leakage current internal ref, dac, and adc off (note 7) 100 na internal voltage reference (c ref = 4.7?) av dd +1.8v, t a = +25 c 1.213 1.25 1.288 av dd +2.2v, t a = +25 c 1.987 2.048 2.109 reference output voltage v ref av dd +2.7v, t a = +25 c 2.425 2.5 2.575 v output-voltage temperaturecoefficient tc (note 7) 15 ppm/ o c ref shorted to agnd 18 ma output short-circuit current i rsc ref shorted to av dd 90 ? line regulation t a = +25 c 25 ?/v i source = 0 to 500? 1.2 load regulation t a = +25 c, v ref = 1.25v i sink = 0 to 50? 1.7 ?/? downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ____________________________________ 5 electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units long-term stability (note 9) 35 ppm/ 1000hrs f = 0.1hz to 10hz, av dd = 3v 50 output noise voltage f = 10hz to 10khz, av dd = 3v 400 ? p-p turn-on settling time buffer only, settle to 0.1% of final value 100 ? temperature sensor temperature measurementresolution adc resolution is 16-bit, 10sps 0.11 c/lsb t a = 0 c to +70 c 0.5 internal temperature-sensormeasurement error t a = -40 c to +85 c 1 c t a = +32 c to +43 c 0.50 t a = +10 c to +50 c 0.5 t a = 0 c to +70 c 0.5 external temperature-sensormeasurement error (note 10) t a = -40 c to +85 c 1 c temperature measurement noise 0.18 c rms temperature measurementpower-supply rejection ratio 0.2 c/v op amp (r l = 10k ? connected to av dd / 2) input offset voltage v os v cm = 0.5v 15 mv offset-error tempco 3 ?/ o c t a = -40 c to +85 c 0.006 1n a t a = 0 c to +70 c4 300 in1+, in2+ t a = 0 c to +50 c2 200 pa t a = -40 c to +85 c 0.025 1n a t a = 0 c to +70 c2 0 600 input bias current (note 7) i bias in1-, in2- t a = 0 c to +50 c 400 pa input offset current i os v i n 1 _ , i n 2 _ = + 0.3v to ( av d d - 0.3v ) ( n ote 7) 1n a input common-mode voltagerange cmvr 0 av dd - 0.35 v 0 v cm 75mv 60 common-mode rejection ratio cmrr 75mv < v cm av dd - 0.35v 60 75 db downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 6 __________________________________________________ _____________________________________ electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units power-supply rejection ratio psrr av dd = +1.8v to +3.6v 76.5 100 db large-signal voltage gain a vol 100mv v out_ av dd - 100mv (note 11) 90 116 db i source = 10a 0.005 i source = 50a 0.025 i source = 100a 0.05 i source = 500a 0.25 sourcing i source = 2m a 0.5 i sink = 10a 0.005 i sink = 50a 0.025 i sink = 100a 0.05 i sink = 500a 0.25 maximum current drive ? v out sinking i sink = 2m a 0.5 v gain bandwidth product gbw unity-gain configuration, c l = 1nf 80 khz phase margin unity-gain configuration, c l = 1nf (note 11) 60 degrees output slew rate sr c l = 200pf 0.04 v/? f = 0.1hz to 10hz 80 input voltage noise unity-gainconfiguration f = 10hz to 10khz 200 ? p-p v out_ shorted to agnd 20 output short-circuit current v out_ shorted to av dd 15 ma power-on time 15 ? spdt switches (sno_, snc_, scm_, hfck enabled) v scm_ = 0v t a = 0? to +50? 45 v scm_ = 0.5v t a = 0? to +50? 50 on-resistance r on v scm_ = 0.5v to av dd 150 t a = -40 c to +85 c 1n a t a = 0 c to +70 c 600 sno_, snc_ off-leakagecurrent (note 7) i sno_ ( off ) i snc_ ( off ) sno_, snc_ = +0.5v,+1.5v; scm_ = +1.5v, +0.5v t a = 0 c to +50 c 400 pa t a = -40 c to +85 c 2 t a = 0 c to +70 c 1.2 scm_ off-leakage current(note 7) i scm_ ( off ) sno_, snc_ = +0.5v,+1.5v; scm_ = +1.5v, +0.5v t a = 0 c to +50 c 0.8 na t a = -40 c to +85 c 2 t a = 0 c to +70 c 1.2 scm_ on-leakage current(note 7) i scm_ ( on ) sno_, snc_ = +0.5v,+1.5v, or open; scm_ = +1.5v, +0.5v t a = 0 c to +50 c 0.8 na input voltage range agnd av dd v turn-on/off time t on /t off break-before-make 100 ns downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ____________________________________ 7 electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units input capacitance sno_, snc_, or scm_ = av dd or agnd; switch connected to enabled mux input 5p f charge pump (10? at reg and 10? external capacitor between cf+ and cf-) maximum output current i out 10 ma no load 3.2 3.3 3.6 output voltage i out = 10ma 3.0 v output voltage ripple 10? external capacitor between cpoutand dgnd, i out = 10ma, excluding esr of external capacitor 50 mv load regulation i out = 10ma, excluding esr of external capacitor 15 20 mv/ma reg input voltage range internal linear regulator disabled 1.6 1.8 v reg input current linear regulator off, charge pump off 3 na cpout input voltage range charge pump disabled 1.8 3.6 v cpout input leakage current charge pump disabled 2 na signal-detect comparator tsel[2:0] = 0 hex 0 tsel[2:0] = 4 hex 50 tsel[2:0] = 5 hex 100 tsel[2:0] = 6 hex 150 differential input-detectionthreshold voltage tsel[2:0] = 7 hex 200 mv differential input-detectionthreshold error 10 mv common-mode input voltagerange agnd av dd v turn-on time 50 ? voltage monitors dv dd monitor supply voltage range for valid reset 1.0 3.6 v trip threshold (dv dd falling) 1.80 1.85 1.95 v dv dd monitor timeout reset period 1.5 s hyse bit set to logic 1 200 dv dd monitor hysteresis hyse bit set to logic 0 35 mv downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 8 __________________________________________________ _____________________________________ electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units dv dd monitor turn-on time 5m s cpout monitor supply voltagerange 1.0 3.6 v cpout monitor trip threshold 2.7 2.8 2.9 v cpout monitor hysteresis 35 mv cpout monitor turn-on time 5m s internal power-on reset voltage 1.7 v 32khz oscillator (32kin, 32kout) clock frequency dv dd = 2.7v 32.768 khz stability dv dd = 1.8v to 3.6v, excluding crystal 25 ppm oscillator startup time 1500 ms crystal load capacitance 6p f low-frequency clock input/output (clk32k) output clock frequency 32.768 khz absolute input to output clockjitter cycle to cycle 5 ns input to output rise/fall time 10% to 90%, 30pf load 5 ns input/output duty cycle 40 60 % high-frequency clock output (clk) f out = f fll 4.8660 4.9152 4.9644 f out = f fll / 2, power-up default 2.4330 2.4576 2.4822 f out = f fll / 4 1.2165 1.2288 1.2411 mhz fll output clock frequency f out = f fll / 8 608.25 614.4 620.54 khz cycle to cycle, fll off 0.15 absolute clock jitter cycle to cycle, fll on 1 ns rise and fall time t r /t f 10% to 90%, 30pf load 10 ns f out = 4.9152mhz 40 60 duty cycle f out = 2.4576mhz, 1.2288mhz, 614.4khz 45 55 % uncalibrated clk frequencyerror fll calibration not performed 35 % digital inputs (sclk, din, cs , upio_, clk32k) input high voltage v ih 0.7 x dv dd v input low voltage v il 0.3 x dv dd v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ____________________________________ 9 electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units dv dd supply voltage 0.7 x dv dd upio_ input high voltage cpout supply voltage 0.7 x cpout v dv dd supply voltage 0.3 x dv dd upio_ input low voltage cpout supply voltage 0.3 x cpout v input hysteresis v hys dv dd = 3.0v 200 mv input current i in v in = dgnd or dv dd (note 7) 0.01 100 na input capacitance v in = dgnd or dv dd 10 pf v in = dv dd or cpout, pullup enabled 0.01 1 upio_ input current v in = dv dd or cpout or 0v, pullup disabled 1 ? upio_ pullup current v in = 0v, pullup enabled, upio inputs are pulled up to dv dd or cpout with pullup enabled 0.5 2 5 ? digital outputs (dout, reset , upio_, clk32k, int, clk) output low voltage v ol i sink = 1ma 0.4 v output high voltage v oh i source = 500? 0.8 x dv dd v dout tri-state leakage current i l 0.01 1 a dout tri-state outputcapacitance c out 15 pf reset output low voltage v ol i sink = 1ma 0.4 v reset output leakage current open-drain output, reset deasserted 0.1 ? i sink = 1ma, upio_ referenced to dv dd 0.4 upio_ output low voltage v ol i sink = 4ma, upio_ referenced to cpout 0.4 v i source = 500?, upio_ referenced to dv dd 0.8 x dv dd upio_ output high voltage v oh i source = 4ma, upio_ referenced to cpout v c p ou t - 0.4 v power requirement analog supply voltage range av dd 1.8 3.6 v digital supply voltage range dv dd 1.8 3.6 v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 10 _________________________________________________ _____________________________________ electrical characteristics (continued) (av dd = dv dd = +1.8v to +3.6v, v ref = +1.25v, external reference, f clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units av dd = dv dd = 3.6v 1.36 2.0 i max everything on,charge pump unloaded, max internal temp-sensor current, clock output buffers unloaded, adc at 512sps av dd = dv dd = 3.3v 1.15 1.7 total supply current i normal all on except charge pump and tempsensor, adc at 512sps, clk output buffer enabled, clock output buffers unloaded 1.17 1.3 ma av dd = dv dd = 3.0v 5.18 6.5 t a = -45? to +85? av dd = dv dd = 3.6v 6.15 9 av dd = dv dd = 3.0v 4.42 5.19 sleep-mode supply current i sleep t a = +25? av dd = dv dd = 3.6v 5.56 8.3 ? t a = -40? to +85? 4 shutdown supply current i shdn all off t a = +25? 1.6 ? note 1: devices are production tested at t a = +25? and t a = +85?. specifications to t a = -40? are guaranteed by design. note 2: guaranteed by design or characterization. note 3: the offset and gain errors are corrected by self-calibration. the calibration process requires measurement to be made atthe selected data rate. the calibration error is therefore in the order of peak-to-peak noise for the selected rate. note 4: eliminate drift errors by recalibration at the new temperature. note 5: the gain error excludes reference error, offset error (unipolar), and zero error (bipolar). note 6: gain-error drift does not include unipolar offset drift or bipolar zero-error drift. it is effectively the drift of the part if zero- scale error is removed. note 7: these specs are obtained from characterization during design or from initial product evaluation. not production tested orguaranteed. note 8: outa/b = +0.5v or +1.5v, swa/b = +1.5v or +0.5v, t a = 0 c to +50 c. note 9: long-term stability is characterized using five to six parts. the bandgaps are turned on for 1000hrs at room temperaturewith the parts running continuously. daily measurements are taken and any obvious outlying data points are discarded. note 10: all of the stated temperature accuracies assume that 1) the external diode characteristic is precisely known (i.e., ideal)and 2) the adc reference voltage is exactly equal to 1.25v. any variations to this known reference characteristic and volt- age caused by temperature, loading, or power supply results in errors in the temperature measurement. the actual tem- perature calculation is performed externally by the microcontroller (?). note 11: values based on simulation results and are not production tested or guaranteed. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 11 output noise (? rms ) rate (sps) gain = 1 gain = 2 gain = 4 gain = 8 10 1.820 3.286 1.345 0.660 40 3.845 3.257 1.928 0.630 50 3.065 2.317 1.631 0.625 60 2.873 2.662 1.519 0.728 200 4.525 2.910 1.397 0.519 240 6.502 2.954 1.596 0.629 400 5.300 80.068 1.686 0.436 512 119.078 282.959 281.056 28.470 table 1. output noise (notes 12, 13, and 14) note 12: v ref = ?.25v, bipolar mode, v in = 1.24912, pga gain = 1, t a = +85?. note 13: c in = 5pf, op-amp noise is considered to be the same as the switching noise. the increase of the op amp? noise contri- bution is due to large input swing (0 to 3.6v). note 14: assume ? sigma peak-to-peak variation; noise-free resolution means no code flicker at given bits?lsb. peak-to-peak resolution (bits) rate (sps) gain = 1 gain = 2 gain = 4 gain = 8 10 16.7 14.8 15.1 15.1 40 15.6 14.8 14.6 15.2 50 15.9 15.3 14.8 15.2 60 16.0 15.1 14.9 15.0 200 15.4 15.0 15.0 15.5 240 14.8 15.0 14.9 15.2 400 15.1 10.2 14.8 15.7 512 10.6 8.4 7.4 9.7 table 2. peak-to-peak resolution external capacitance (pf) parameter 0 (note 15) 50 100 500 1000 5000 resistance (k ? ) 350 60 30 10 4 1 table 3. maximum external source impedance without 16-bit g ain error note 15: 2pf parasitic capacitance is assumed, which represents pad and any other parasitic capacitance. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 12 _________________________________________________ _____________________________________ timing characteristics (figures 1 and 19) (av dd = dv dd = +1.8v to +3.6v, external v ref = +1.25v, clk32k = 32.768khz (external clock), c reg = 10?, c cpout = 10?, 10? between cf+ and cf-, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units sclk operating frequency f sclk 0 10 mhz sclk cycle time t cyc 100 ns sclk pulse-width high t ch 40 ns sclk pulse-width low t cl 40 ns din to sclk setup t ds 30 ns din to sclk hold t dh 0n s sclk fall to dout valid t do c l = 50pf, figure 2 40 ns cs fall to output enable t dv c l = 50pf, figure 2 48 ns cs rise to dout disable t tr c l = 50pf, figure 2 48 ns cs to sclk rise setup t css 20 ns cs to sclk rise hold t csh 0n s dv dd monitor timeout period t dslp (note 16) 1.5 s wake-up (wu) pulse width t wu minimum pulse width required to detect awake-up event 1 s shutdown delay t dpu the delay for shdn to go high after a valid wake-up event 1 s the turn-on time for the high-frequencyclock and fll (flle = 1) (note 17) 10 ms hfck turn-on time t dfon if flle = 0, the turn-on time for the high-frequency clock (notes 7, 18) 10 ? crdy to int delay t dfi the delay for crdy to go low after thehfck clock output has been enabled (note 19) 7.82 ms hfck disable delay t dfof the delay after a shutdown command hasasserted and before hfck is disabled (note 20) 1.95 ms shdn assertion delay t dpd (note 21) 2.93 ms note 16: the delay for the sleep voltage monitor output, reset , to go high after v dd rises above the reset threshold. this is largely driven by the startup of the 32khz oscillator. note 17: it is gated by an and function with three inputs?he external reset signal, the internal dv dd monitor output, and the external shdn signal. the time delay is timed from the internal lov dd going high or the external reset going high, whichever happens later. hfck always starts in the low state. note 18: if flle = 0, the internal signal crdy is not generated by the fll block and int or int are deasserted. note 19: crdy is used as an interrupt signal to inform the ? that the high-frequency clock has started. only valid if flle = 1. note 20: t dfof gives the ? time to clean up and go into sleep-override mode properly. note 21: t dpd is greater than the hfck delay for the max1359b chip to clean up before losing power. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 13 t ds t css t dh t dv t do t tr cs sclk din dout t csh t cyc t ch t cl t csh figure 1. detailed serial-interface timing dv dd c load = 50pf 6k ? douta) for enable, high impedance to v oh and v ol to v oh for disable, v oh to high impedance b) for enable, high impedance to v ol and v oh to v ol for disable, v ol to high impedance dout 6k ? c load = 50pf figure 2. dout enable and disable time load circuits typical operating characteristics (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) 200 300 500400 600 700 1.8 2.4 2.1 2.7 3.0 3.3 3.6 dv dd supply current vs. dv dd supply voltage max1359b toc01 dv dd (v) supply current ( a) normal modeclk buffer disabled 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 1.8 2.4 2.1 2.7 3.0 3.3 3.6 max1359b toc02 dv dd (v) supply current ( a) dv dd supply current vs. dv dd supply voltage sleep mode, clk buffer disabled32khz osc, rtc, dv dd monitor enabled 0 0.2 0.60.4 0.8 1.0 1.8 2.4 2.1 2.7 3.0 3.3 3.6 max1359b toc03 dv dd (v) supply current ( a) dv dd supply current vs. dv dd supply voltage sleep mode,all functions disabled downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 14 _________________________________________________ _____________________________________ typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) dv dd supply current vs. temperature max1359b toc04 temperature ( c) supply current ( a) 60 35 10 -15 300 400 500 600 700200 -40 85 dv dd = 3.0v normal modeclk buffer disabled dv dd = 1.8v 0 1.00.5 2.01.5 2.5 3.0 -40 10 -15 35 60 85 max1359b toc05 temperature ( c) supply current ( a) dv dd supply current vs. temperature sleep mode, clk buffer disabled32khz osc, rtc, dv dd monitor enabled dv dd = 3.0v dv dd = 1.8v dv dd supply current vs. temperature max1359b toc06 temperature ( c) supply current ( a) 60 35 10 -15 0.2 0.4 0.6 0.8 1.0 0 -40 85 dv dd = 3.0v sleep mode, allfunctions disabled dv dd = 1.8v 250 275 300 325 350 375 400 425 450 1.8 2.4 2.1 2.7 3.0 3.3 3.6 max1359b toc07 av dd (v) supply current ( a) av dd supply current vs. av dd supply voltage normal mode 1.5 2.0 3.02.5 3.5 4.0 1.8 2.4 2.1 2.7 3.0 3.3 3.6 av dd supply current vs. av dd supply voltage max1359b toc08 av dd (v) supply current ( a) sleep mode, 32khz osc, rtc, dv dd monitor enabled 1.0 1.2 1.61.4 1.8 2.0 1.8 2.4 2.1 2.7 3.0 3.3 3.6 av dd supply current vs. av dd supply voltage max1359b toc09 av dd (v) supply current ( a) sleep mode, all functions disabled 200 225 250 275 300 325 350 375 400 -40 -15 10 35 60 85 max1359b toc10 temperature ( c) supply current ( a) normal mode av dd supply current vs. temperature av dd = 3.0v av dd = 1.8v 1.0 2.01.5 3.02.5 3.5 4.0 -40 10 -15 35 60 85 max1359b toc11 temperature ( c) supply current ( a) av dd supply current vs. temperature av dd = 3.0v av dd = 1.8v sleep mode,32khz osc, rtc, dv dd monitor enabled av dd supply current vs. temperature max1359b toc12 temperature ( c) supply current ( a) 60 35 10 -15 1.2 1.4 1.6 1.8 2.01.0 -40 85 av dd = 3.0v sleep mode, allfunctions disabled av dd = 1.8v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ______________________________________________________________________________________ 15 typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) 2.1 2.32.2 2.52.4 2.72.6 2.8 -40 10 -15 35 60 85 internal oscillator frequency vs. temperature max1359b toc13 temperature ( c) internal oscillator frequency (mhz) c a: fll disabled; av dd , dv dd = 1.8v b: fll enabledc: fll disabled; av dd , dv dd = 3.0v b a clk = 2.4576mhz 2.20 2.25 2.30 2.35 2.40 2.45 2.50 2.55 2.60 1.8 2.4 2.1 2.7 3.0 3.3 3.6 internal oscillator frequency vs. supply voltage max1359b toc14 av dd , dv dd (v) internal oscillator frequency (mhz) fll enabled clk = 2.4576mhz fll disabled 3.02.5 2.0 1.5 1.0 1.8 2.7 2.1 2.4 3.0 3.3 3.6 reference output voltage vs. supply voltage max1359b toc15 av dd (v) reference output voltage (v) c b a a: v ref = 1.25v b: v ref = 2.048v c: v ref = 2.5v 1.25101.2505 1.2500 1.2495 1.2490 -50 250 50 150 350 450 reference output voltage vs. output current max1359b toc16 output current ( a) v ref (v) av dd = 1.8v v ref = 1.25v 2.0472 2.04762.0474 2.04802.0478 2.04842.0482 2.0486 reference output voltage vs. output current max1359b toc17 v ref (v) av dd = 2.5v v ref = 2.048v -50 250 50 150 350 450 output current ( a) 2.5030 2.50362.5034 2.5032 2.5038 2.5040 2.5042 2.5044 2.5046 2.5048 2.5050 max1359b toc18 v ref (v) -50 250 50 150 350 450 output current ( a) av dd = 3.0v v ref = 2.5v reference output voltage vs. output current 0.9970 0.9975 0.9980 0.9985 0.9990 0.9995 1.0000 1.0005 1.0010 -40 -15 10 35 60 85 normalized reference output voltage vs. temperature max1359b toc19 temperature ( c) normalized reference voltage (v) v ref = 1.25v 0.9970 0.9975 0.9980 0.9985 0.9990 0.9995 1.0000 1.0005 1.0010 -40 -15 10 35 60 85 normalized reference output voltage vs. temperature max1359b toc20 temperature ( c) normalized reference voltage (v) v ref = 2.048v 0.9970 0.9975 0.9980 0.9985 0.9990 0.9995 1.0000 1.0005 1.0010 -40 -15 10 35 60 85 normalized reference output voltage vs. temperature max1359b toc21 temperature ( c) normalized reference voltage (v) v ref = 2.5v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 16 _________________________________________________ _____________________________________ typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) 1s/div reference voltage output noise (0.1hz to 10hz) 50 v/div max1359b toc22 v ref = +1.25v av dd = +1.8v reference voltage output noise vs. frequency max1359b toc23 frequency (hz) 1k 100 10 1000 1 10k 10,000 100 v ref = 1.25v noise (nv/ hz) reference voltage output noise vs. frequency max1359b toc24 frequency (hz) 1k 100 10 1000 1 10k 10,000 100 v ref = 2.048v noise (nv/ hz) reference voltage output noise vs. frequency max1359b toc25 frequency (hz) 1k 100 10 1000 1 10k 10,000 100 v ref = 2.5v noise (nv/ hz) -12 -8 -10 -4-6 0 -2 2 -40 10 -15 35 60 85 adc mux input dc current vs. temperature max1359b toc26 temperature ( c) input current ( a) av dd = 1.8v v ain = 0.5v -0.25 -0.15 0.05 -0.05 0.15 0.25 04 0 0 200 600 800 1000 dac inl vs. output code max1359b toc27 output code inl (lsb) av dd = 1.8v v ref = 1.25v -0.25 -0.15 0.05 -0.05 0.15 0.25 0 400 200 600 800 1000 dac inl vs. output code max1359b toc28 output code inl (lsb) av dd = 2.5v v ref = 2.048v -0.25 -0.15 0.05 -0.05 0.15 0.25 04 0 0 200 600 800 1000 dac inl vs. output code max1359b toc29 output code inl (lsb) av dd = 3.0v v ref = 2.5v -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 04 0 0 200 600 800 1000 dac dnl vs. output code max1359b toc30 output code dnl (lsb) av dd = 1.8v v ref = 1.25v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ______________________________________________________________________________________ 17 typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 0 400 200 600 800 1000 dac dnl vs. output code max1359b toc31 output code dnl (lsb) av dd = 2.5v v ref = 2.048v -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 0 400 200 600 800 1000 dac dnl vs. output code max1359b toc32 output code dnl (lsb) av dd = 3.0v v ref = 2.5v 1.240 1.242 1.244 1.246 1.248 0 0.50 1.00 1.50 0.25 0.75 1.25 1.75 2.00 dac output voltage vs. output source current max1359b toc33 source current (ma) dac output voltage (v) code = 3ff hexav dd = 1.8v, 3.0v 0 0.05 0.10 0.15 0.20 0.25 0.30 dac output voltage vs. output sink current max1359b toc34 dac output voltage (v) 0 0.50 1.00 1.50 0.25 0.75 1.25 1.75 2.00 source current (ma) code = 020 hex av dd = 1.8v av dd = 3.0v 650640 630 610 600 1.8 2.7 2.1 2.4 3.0 3.3 3.6 dac output voltage vs. analog supply voltage max1359b toc35 av dd (v) dac output voltage (mv) code = 200 hex 620 620 622 626624 628 630 -40 10 -15 35 60 85 dac output voltage vs. temperature max1359b toc36 temperature ( c) dac output voltage (mv) av dd = 3.0v av dd = 1.8v v ref = 1.25v code = 200 hex -5 -3-4 -1-2 10 2 -40 10 -15 35 60 85 dac fba/b input bias current vs. temperature max1359b toc37 temperature ( c) input bias current ( a) av dd = 1.8v v ain = 0.5v 1s/div dac output noise (0.1hz to 10hz) 50 v/div max1359b toc38 av dd = +1.8v v ref = +1.25v dac code = 3ff hex dac output noise vs. frequency max1359b toc39 frequency (hz) 1k 100 10 1000 1 10k 10,000 100 dac code = 3ff hexv ref = 2.5v noise (nv/ hz) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 18 _________________________________________________ _____________________________________ typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) 40 s/div dac large-signal output step response max1359b toc40 v ref = +1.25v av dd = +3.0v cs 2v/div out_1v/div op-amp input offset voltage vs. temperature max1359b toc41 temperature ( c) input offset voltage (mv) 60 35 10 -15 6.3 6.6 6.9 7.2 7.56.0 -40 85 av dd = 1.8v v cm = 0.5v av dd = 3.0v 0 42 86 10 12 -40 10 -15 35 60 85 max1359b toc42 temperature ( c) input bias current (pa) op-amp input bias current vs. temperature av dd = 1.8v v cm = 0.5v -2 0 2 4 6 8 10 12 14 -40 -15 10 35 60 85 max1359b toc43 temperature ( c) input bias current (pa) op-amp input bias current vs. temperature av dd = 3.0v v cm = 0.5v 0 50 150100 200 250 0 0.50 0.75 0.25 1.00 1.25 1.50 1.75 2.00 op-amp output voltage vs. output sink current max1359b toc44 sink current (ma) output voltage (mv) unity gain, v in_ + = 0v av dd = 1.8v av dd = 3.0v 2.80 2.84 2.922.88 2.96 3.00 0 0.50 0.75 0.25 1.00 1.25 1.50 1.75 2.00 op-amp output voltage vs. output source current max1359b toc45 source current (ma) output voltage (v) av dd = 3.0v unity gain, v in_ + = av dd downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ______________________________________________________________________________________ 19 typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) 1.8 2.7 2.1 2.4 3.0 3.3 3.6 op-amp output voltage vs. av dd supply voltage max1359b toc48 av dd (v) output voltage (mv) 500.2 500.4 500.6 500.8 501.0500.0 unity gain, v in_ + = 0.5v r l = 10k ? max1359b toc49 frequency (hz) 1k 100 10 1000 1 10k 10,000 100 noise (nv/ hz) op-amp output noise vs. frequency unity gain, v in_ + = 0.5v 25 35 5545 65 75 0 1.0 0.5 1.5 2.0 2.5 3.0 spdt on-resistance vs. v com voltage max1359b toc50 v com (v) r on ( ? ) av dd = 3.0v av dd = 1.8v 50 70 110 90 130 150 01 . 0 0.5 1.5 2.0 2.5 3.0 spst on-resistance vs. v com voltage max1359b toc51 v com (v) r on ( ? ) av dd = 3.0v av dd = 1.8v 1.60 1.65 1.70 1.75 1.80 op-amp output voltage vs. output source current max1359b toc46 output voltage (v) unity gain, v in_ + = av dd av dd = 1.8v 0 0.50 0.75 0.25 1.00 1.25 1.50 1.75 2.00 source current (ma) op-amp output voltage vs. temperature max1359b toc47 temperature ( c) output voltage (mv) 60 35 10 -15 500.2 500.4 500.6 500.8 501.0500.0 -40 85 av dd = 1.8v av dd = 3.0v unity gain, v in_ + = 0.5v r l = 10k ? downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 20 _________________________________________________ _____________________________________ typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) spdt on-resistance vs. temperature max1359b toc52 temperature ( c) r on ( ? ) 60 35 10 -15 33 36 39 42 4530 -40 85 av dd = 3.0v i com = 1ma av dd = 1.8v 82 8885 9491 97 100 -40 10 -15 35 60 85 max1359b toc53 temperature ( c) r on ( ? ) spst on-resistance vs. temperature av dd = 1.8v, 3.0v i com = 1ma spdt/spst on/off-leakage current vs. temperature max1359b toc54 temperature ( c) leakage current (pa) 60 35 10 -15 1 10 100 0.1 -40 85 on-leakage off-leakage av dd = 1.8v v cm = 0v 15 2520 3530 40 45 1.8 2.4 2.7 2.1 3.0 3.3 3.6 spdt/spst switching time vs. av dd supply voltage max1359b toc55 av dd (v) switching times (ns) t on t off spdt/spst switching time vs. temperature max1359b toc56 temperature ( c) switching times (ns) 60 35 10 -15 34 38 42 46 5030 -40 85 av dd = 1.8v t on t off spdt/spst switching time vs. temperature max1359b toc57 temperature ( c) switching times (ns) 60 35 10 -15 19 23 27 31 3515 -40 85 av dd = 3.0v t on t off downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ______________________________________________________________________________________ 21 typical operating characteristics (continued) (dv dd = av dd = 1.8v, ref = +1.25v c cpout = 10?, t a = +25 c, unless otherwise noted.) 20 s/div charge-pump output voltage ripple max1359b toc63 dv dd = +1.8v i load = 10ma cpout20mv/div ac-coupled -0.20 -0.10-0.15 0 -0.05 0.05 0.10 -40 10 -15 35 60 85 max1359b toc58 temperature ( c) % deviation voltage supervisor threshold vs. temperature dv dd supervisor cpout supervisor 3.0 3.23.1 3.43.3 3.5 3.6 04 26 8 1 0 charge-pump output voltage vs. output current max1359b toc59 output current (ma) cpout voltage (v) dv dd = 1.8v 3.10 3.14 3.223.18 3.26 3.30 -40 10 -15 35 60 85 charge-pump output voltage vs. temperature max1359b toc60 temperature ( c) cpout voltage (v) dv dd = 3.0v dv dd = 1.8v i out = 10ma 0 20 6040 80 100 08 41 2 1 6 2 0 charge-pump output resistance vs. capacitance max1359b toc61 c f ( f) output resistance ( ? ) dv dd = 1.8v i out = 10ma 0 10 3020 40 50 04 26 8 1 0 charge-pump output voltage ripple vs. output current max1359b toc62 output current (ma) output voltage ripple (mv) dv dd = 1.8v downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 22 _________________________________________________ _____________________________________ pin name function 1 clk clock output. default is 2.457mhz output clock for ?. 2 upio2 user-programmable input/output 2. see the upio2_ctrl register section for functionality. 3 upio3 user-programmable input/output 3. see the upio3_ctrl register section for functionality. 4 upio4 user-programmable input/output 4. see the upio4_ctrl register section for functionality. 5d o u t serial-data output. data is clocked out on sclk? falling edge. high impedance when cs is high, when upio/spi passthrough mode is enabled, dout mirrors the state of upio1. 6 sclk serial-clock input. clocks data in and out of the serial interface. 7 din serial-data input. data is clocked in on sclk? rising edge. 8 cs active-low chip-select input. data is not clocked into din unless cs is low. when cs is high, dout is high impedance. high impedance when cs is high, when upio/spi passthrough mode is enabled, dout mirrors the state of upio1. 9 int programmable active-high/low interrupt output. adc, upio wake-up, alarm, and voltage-monitor events. 10 clk32k 32khz clock input/output. outputs 32khz clock for ?. can be programmed as an input by enabling the io32e bit to accept an external 32khz input clock. the rtc, pwm, and watchdog timer always use the internal 32khz clock derived from the 32khz crystal. 11 reset active-low open-drain reset output. remains low while dv dd is below the 1.8v voltage threshold and stays low for a timeout period (t dslp ) after dv dd rises above the 1.8v threshold. reset also pulses low when the watchdog timer times out and holds low during por until the 32khz oscillator stabilizes. 12 32kout 32khz crystal output. connect external 32khz watch crystal between 32kin and 32kout. 13 32kin 32khz crystal input. connect external 32khz watch crystal between 32kin and 32kout. 14 sno1 analog switch 1 normally open terminal. analog input to mux. 15 scm1 analog switch 1 common terminal. analog input to mux. 16 snc1 analog switch 1 normally closed terminal. analog input to mux (open on por). 17 sno2 analog switch 2 normally open terminal. analog input to mux. 18 scm2 analog switch 2 common terminal. analog input to mux (open on por). 19 snc2 analog switch 2 normally closed terminal. analog input to mux. 20 out1 amplifier 1 output. analog input to mux. 21 in1- amplifier 1 inverting input. analog input to mux. 22 in1+ amplifier 1 noninverting input pin description downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 23 pin name function 23 swa daca spst shunt switch input. connects to outa through a spst switch. 24 fba daca force-sense feedback input. analog input to mux. 25 outa daca force-sense output. analog input to mux. 26 agnd analog ground 27 av dd analog supply voltage. also adc reference voltage during av dd measurement. bypass to agnd with 10? and 0.1? capacitors in parallel as close to the pin as possible. 28 in2+ amplifier 2 noninverting input 29 in2- amplifier 2 inverting input. analog input to mux. 30 out2 amplifier 2 output. analog input to mux. 31 ain2 analog input 2. analog input to mux. inputs have internal programmable current source for externaltemperature measurement. 32 ain1 analog input 1. analog input to mux. inputs have internal programmable current source for externaltemperature measurement. 33 ref reference input/output. output of the reference buffer amplifier or external reference input. disabled at power-up to allow external reference. reference voltage for adc and dac. 34 reg linear voltage-regulator output. charge-pump-doubler input voltage. bypass reg with a 10? capacitor to dgnd for charge-pump regulation. 35 cf- 36 cf+ charge-pump flying capacitor terminals. connect an external 10? (typ) capacitor between cf+ and cf-. 37 cpout c har g e- p um p outp ut. c onnect an exter nal 10? ( typ ) r eser voi r cap aci tor b etw een c p o u t and d gn d . ther e i s a l ow thr eshol d d i od e b etw een d v d d and c p ou t. when the char g e p um p i s d i sab l ed , c p ou t i s p ul l ed up w i thi n 300m v ( typ ) of d v d d . 38 dv dd digital supply voltage. bypass to dgnd with 10? and 0.1? capacitors in parallel as close to the pin aspossible. 39 dgnd digital ground. also ground for cascaded linear voltage regulator and charge-pump doubler. 40 upio1 u ser - p r og r am m ab l e inp ut/o utp ut 1. s ee the u p io1_c trl reg i ster for functionality. ? pe xp osed p ad . leave unconnected or connect to agn d . pin description (continued) downloaded from: http:///
max1359b detailed description the max1359b das features a multiplexed differential16-bit adc, 10-bit force-sense dac, an rtc with an alarm, a selectable bandgap voltage reference, a signal- detect comparator, 1.8v and 2.7v voltage monitors, and wake-up control circuitry, all controlled by a 4-wire serial interface. (see figure 3 for the functional diagram). the das directly interfaces to various sensor outputs and, once configured, provides the stimulus, signal conditioning, and data conversion, as well as ? sup- port. see the applications section for sample max1359b applications.the 16-bit adc features programmable continuous con- version rates as shown in table 4, and gains of 1, 2, 4, and 8 (table 5) to suit applications with different power and dynamic range constraints. the force-sense dacprovides 10-bit resolution for precise sensor applica- tions. the adcs and dac utilize a low-drift 1.25v inter- nal bandgap reference for conversions and full-scale range setting. the rtc has a 138-year range and pro- vides an alarm function that can be used to wake up 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 24 _________________________________________________ _____________________________________ temp sensor ref agnd outa out2 scm2 out1 agnd ref inm1 in2- scm1 fba ain1 sno1 snc1 temp+ temp- sno2 snc2 ain2 10:1 mux neg 10:1 mux pos av = 1, 2, 4, 8 v/v polarity flipper prog. vos pga av = 1, 1.6384, 2 v/v upio dgnd agnd av dd dv dd serial interface din cs dout sclk 1.25v bandgap ref 16-bit adc in+in- ref op1 10-bit dac outa ref fba buf swa pga out1 sno1 snc1 scm1 cmp upio1upio2 upio3 upio4 32.768khz oscillator 32kin 32kout watchdog timer 4.9152mhz hf oscillator and fll clk clk32k ain2 ain1 interrupt int pwm clk32k input/output control dv dd (1.8v) voltage monitor rtc and alarm sno2 snc2 scm2 charge- pump doubler cf+ cf- in1- in1+ prog current source temp+temp- 32k ain2 ain1 cpout (2.7v) voltage monitor linear 1.65v voltage regulator cpout reg status 4 reset ldvd ald crdysdc add adou upr<4:1> 4 upf<4:1> lcpd 16 control logic hfclk m32k m32k m32k hfclk wdto dv dd max1359b op2 out2 in2- in2+ spdt1 spdt2 figure 3. functional diagram downloaded from: http:///
the system or cause an interrupt at a predefined time.the power-supply voltage monitor detects when dv dd falls below a trip threshold voltage of +1.8v, assertingreset . the max1359b uses a 4-wire serial interface to communicate directly between spi, qspi, ormicrowire devices for system configuration and readback functions. analog-to-digital converter (adc) the max1359b includes a sigma-delta adc with pro-grammable conversion rate, a pga, and a dual 10:1 input mux. when performing continuous conversions at 10sps or single conversions at the 40sps setting (effec- tively 10sps due to four sample sigma-delta settling), the adc has 16-bit noise-free resolution. the noise-free resolution drops to 10 bits at the maximum sampling rate of 512sps. differential inputs support unipolar (between 0 and v ref ) and bipolar (between ? ref ) modes of operation. note: avoid combinations of input signal and pga gains that exceed the reference rangeat the adc input. the adou bit in the status register indicates if the adc has over-ranged or under-ranged. zero-scale and full-scale calibrations remove offset and gain errors. direct access to gain and zero-scale cali- bration registers allows system-level offset and gain cal- ibration. the zero-scale adjustment register allows intentional positive offset skewing to preserve unipolar- mode resolution for signals that have a slight negative offset (i.e., unipolar clipping near zero can be removed). perform adc calibration whenever the adc configura- tion, temperature, or av dd changes. the adc-done sta- tus can be programmed to provide an interrupt on intor on any upio_. pga gain an integrated pga provides four selectable gains: +1v/v,+2v/v, +4v/v, and +8v/v to maximize the dynamic range of the adc. bits gain1 and gain0 set the gain (see the adc register for more information). the pga gain is implemented in the digital filter of the adc. adc modulator the max1359b performs analog-to-digital conversionsusing a single-bit, 3rd-order, switched-capacitor sigma- delta modulator. the sigma-delta modulation converts the input signal into a digital pulse train whose average duty cycle represents the digitized signal information. the pulse train is then processed by a digital decimation filter. the modulator provides 2nd-order frequency shap- ing of the quantization noise resulting from the single-bit quantizer. the modulator is fully differential for maximum signal-to-noise ratio and minimum susceptibility to power-supply noise. signal-detect comparator int asserts (and remains asserted) within 30? whenthe differential voltage on the selected analog inputs exceeds the signal-detect comparator trip threshold. the signal-detect comparator? differential input trip threshold (i.e., offset) is user selectable and can be pro- grammed to the following values: 0mv, 50mv, 100mv, 150mv, or 200mv. analog inputs the adc provides two external analog inputs: ain1and ain2. the rail-to-rail inputs accept differential or single-ended voltages, or external temperature-sensing diodes. the unused op amps, switches, or dac inputs and output pins can also be used as rail-to-rail analog inputs if the associated function is disabled. analog input protection internal protection diodes clamp the analog inputs toav dd and agnd, and allow the channel input to swing from (agnd - 0.3v) to (av dd + 0.3v). for accurate conversions near full scale, the inputs must not exceedav dd by more than 50mv or be lower than agnd by 50mv. if the inputs exceed (agnd - 0.3v) to (av dd + 0.3v), limit the current to 50ma. analog mux the max1359b includes a dual 10:1 mux for the positiveand negative inputs of the adc. figure 3 illustrates which signals are present at the inputs of each mux. the muxp[3:0] and muxn[3:0] bits of the mux register select the input to the adc and the signal-detect comparator (tables 8 and 9). see the mux register description in the register definitions section for multiplexer functionality. the pol bit of the adc register swaps the polarity of muxoutput signals to the adc. digital filtering the max1359b contains an on-chip digital lowpass fil-ter that processes the data stream from the modulator using a sinc 4 (sinx/x) 4 response. the sinc 4 filter has a settling time of four output data periods (4 x 200ms).the max1359b has 25% overrange capability built into the modulator and digital filter: figure 4 shows the filter frequency response. the sinc 4 characteristic -3db cutoff frequency is 0.228 times the first notch frequency. hf n sin n f f sin f f m m () = ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1 4 max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 25 downloaded from: http:///
max1359b the output data rate for the digital filter correspondswith the positioning of the first notch of the filter? fre- quency response. the notches of the sinc 4 filter are repeated at multiples of the first notch frequency. thesinc 4 filter provides an attenuation of better than 100db at these notches. for example, 50hz is equal tofive times the first notch frequency and 60hz is equal to six times the first notch frequency. force-sense dac the max1359b incorporates a 10-bit force-sense dac.the dac? reference voltage sets the full-scale range. program the daca_op register using the serial inter- face to set the output voltages of the dac at outa. shorting fba and outa configures the dac in a unity- gain setting. connecting resistors in a voltage-divider configuration between outa, fba, and gnd sets a dif- ferent closed-loop gain for the output amplifier (see the applications information section). the dac output amplifier typically settles to ?.5 lsbfrom a full-scale transition within 50? (unity gain and loaded with 10k ? in parallel with 200pf). loads of less than 1k ? may degrade performance. see the typical operating characteristics for the source-and-sink capability of the dac output.the max1359b features a software-programmable shutdown mode for the dac (see the daca_op register section). dac output outa goes high imped- ance when powered down. the dac is normally pow-ered down at power-on reset. charge pump the charge pump provides >3v at cpout with a maxi-mum 10ma load. enable the charge pump through the ps_vmons register. the charge pump is powered from dv dd . see figures 5 and 6 for block diagrams of the charge pump and linear regulator. the chargepump is disabled at power-on reset. 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 26 _________________________________________________ _____________________________________ frequency (hz) gain (db) 100 80 60 40 20 -160 -120 -80 -40 0 -200 0 120 figure 4. filter frequency response op 1.22v 1.65v linear 1.65v voltage regulator dv dd reg ldoe ldoe figure 5. linear-regulator block diagram cf+ cf- cpout reg m32k charge-pump doubler nonoverlap clock generator cpe figure 6. charge-pump block diagram downloaded from: http:///
an internal clock drives the charge-pump clock andadc clock. the charge pump delivers a maximum 10ma of current to external devices. the droop and the ripple depend on the clock frequency (f clk = 32.768khz / 2), switch resistances (r switch = 5 ? ), and the external capacitors (10?) along with theirrespective esrs, as shown below. voltage supervisors the max1359b provides voltage supervisors to monitordv dd and cpout. the first supervisor monitors the dv dd supply voltage. reset asserts and sets the corre- sponding ldvd status bit when dv dd falls below the 1.8v threshold voltage. when the dv dd supply voltage rises above the threshold during power-up, reset deasserts after a nominal 1.5s timeout period to give thecrystal oscillator time to stabilize. set the threshold hys- teresis using the hyse bit of the ps_vmons register. see the ps_vmons register section for configuring hys- teresis. there is no separate voltage monitor for av dd , but the analog supply is covered by the dv dd monitor in many applications where dv dd and av dd are externally connected together. multiple supply applications whereav dd and dv dd are not connected together require a separate external voltage monitor for av dd . see figure 7 for a block diagram of the dv dd voltage supervisor. the second voltage monitor tracks the charge-pumpoutput voltage, cpout. if cpout falls below the 2.7v threshold, a corresponding register status bit (lcpd) is set to flag the condition. the cpout monitor output can also be mapped to the interrupt generator and out- put on int. the cpout monitor can be used as a 3v av dd monitor in applications where the charge pump is disabled and cpout is connected to av dd . av dd must be greater or equal to dv dd when cpout is used to monitor av dd. see figure 8 for a block diagram of the cpout voltage supervisor. interrupt generator (int) the interrupt generator provides an interrupt to anexternal ?. the source of the interrupt is generated by the status register and can be masked and unmasked through the imsk register. crdy is unmasked by default and int is active-high at power-on reset. int is programmable as active-high and active-low. possible sources include a rising or falling edge of upio_, an rtc alarm, an adc conversion completion, or the volt- age-supervisor outputs. the interrupt causes int to assert when configured as an interrupt output. vi r r fc r esr esr v i fc i esr droop out out out clk f switch c c ripple out clk cpout out c f cpou t cpout = =+ ++ =+ 1 24 2 max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 27 cmp analog 2:1 mux control logic reset dv dd 1.25v 1.8vth 2.0vth ldvd lsde lsde hyse por rste dv dd (1.8v) voltage monitor wdto figure 7. dv dd voltage-supervisor block diagram downloaded from: http:///
max1359b crystal oscillator the on-chip oscillator requires an external crystal (orresonator) connected between 32kin and 32kout with a 32.768khz operating frequency. this oscillator is used for the rtc, alarm, pwm, watchdog, charge pump, and fll. in any crystal-based oscillator circuit, the oscillator frequency is sensitive to the capacitive load (c l ). c l is the capacitance that the crystal needs from the oscillator circuit and not the capacitance of thecrystal. the input capacitance across the 32kin and 32kout is 6pf. choose a crystal with a 32.768khz oscillation frequency and a 6pf capacitive load such as the c-002rx32-e from epson crystal. using a crys- tal with a c l that is larger than the load capacitance of the oscillator circuit causes the oscillator to run fasterthan the specified nominal frequency of the crystal or to not start up. see figures 9 and 10 for block diagramsof the crystal oscillator and the clk32k i/o. real-time clock (rtc) the integrated rtc provides the current time informationfrom a 32-bit counter and subsecond counts from an 8- bit ripple counter. an internally generated reference clock of 256hz (derived from the 32.768khz crystal) dri- ves the 8-bit subsecond counter. an overflow of the 8-bit subsecond counter inputs a 1hz clock to increment the 32-bit second counter. the rtc 32-bit second counter is translatable to calendar format with firmware. all 40 bits (32-bit second counter and 8-bit subsecond counter) must be clocked in or out for valid data. the rtc and the 32.768khz crystal oscillator consume less than 1? when the rest of the ic is powered down. time-of-day alarm program the al_day register with a 20-bit value, whichcorresponds to a time 1s to 12 days later than the cur- rent time with a 1s resolution. the alarm status bit, ald, asserts when the 20 bits of the al_day register match- es the 20 lsbs of the 32-bit second counter. the ade bit automatically clears when the time-of-day alarm trips. the time-of-day alarm causes the device to exit sleep mode. watchdog enable the watchdog timer by writing a 1 to the wdebit in the clk_ctrl register. after enabling the watch- dog timer, the device asserts reset for 250ms, if the watchdog address register is not written every 500ms.due to the asynchronous nature of the watchdog timer, the watchdog timeout period varies between 500ms and 750ms. write a 0 to the wde bit to disable the watchdog timer. see figure 11 for a block diagram of the watchdog timer. 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 28 _________________________________________________ _____________________________________ cmp cpout 1.25v 2.7vth lcpd cpde cpde cpout (2.7v) voltage monitor figure 8. cpout voltage-supervisor block diagram 32kin 32kout 32.768khz oscillator 32khz oscillator osce 32k figure 9. 32khz crystal-oscillator block diagram io32e clk32k ck32e osce clk32k i/o control 2:1 mux 1 0 io32e io32e 32k m32k figure 10. clk32k i/o block diagram downloaded from: http:///
high-frequency clock an internal oscillator and a frequency-locked loop (fll)are used to generate a 4.9152mhz ?% high-frequen- cy clock. this clock and derivatives are used internally by the adc, analog switches, and pwm. this clock sig- nal outputs to clk. when the fll is enabled, the high- frequency clock is locked to the 32.768khz reference. if the fll is disabled, the high-frequency clock is free- running. at power-up, the clk pin defaults to a 2.4576mhz clock output, which is compatible with most ?s. see figure 12 for a block diagram of the high-fre- quency clock. user-programmable i/os the max1359b provides four digital programmablei/os (upio1?pio4). configure upios as logic inputs or outputs using the upio control register. configure the internal pullups using the upio setup register, if required. at power-up, the upio? are internally pulledup to dv dd . upio_ outputs can be referenced to dv dd or cpout. see the upio__ctrl register and upio_spi register sections for more details on config- uring the upio_ pins. program each upio1?pio4 as one of the following: general-purpose input power-mode control analog switch (spst) and spdt control input adc data-ready output general-purpose output pwm output alarm output spi passthrough max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 29 d q q r ck d q q r ck divide- by-8192 32k wde por wdw watchdog timer por pulses high during power-up. wdw pulses high during watchdog register write. 4hz wdto figure 11. watchdog timer block diagram m32k tune<8:0> hfce flle crdy hfclk 1, 2, 4, 8 divider 2:1 mux clk clke cksel<1:0> cksel2 1 0 4.9152mhz hf oscillator and fll 4.9152mhz 32.768khz frequency compare freq error digitally controlled oscillator frequency integrator figure 12. high-frequency clock and fll block diagram downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 30 _________________________________________________ _____________________________________ temperature sensor the internal temperature sensor measures die tempera-ture and the external temperature sensor measures remote temperatures. use the internal temperature sen- sor or external temperature sensor (remote transistor/ diode) with the adc and internal current sources to measure the temperature. for either method, two to four currents are passed through a p-n junction and sense resistor, and its temperature is calculated by a ? using the diode equation and the forward-biased junc- tion voltage drops measured by the adc. the tempera- ture offset between the internal p-n junction and ambient is negligible. for the four and eight measure- ment methods, the ratio of currents used in the diode calculations is precisely known since the adc mea- sures the resulting voltage across the same sense resistor. see figure 13 for a block diagram of the tem- perature sensor. two-current method for the two-current method, currents i 1 and i 2 are passed through a p-n junction. this requires two v be measurements. temperature measurements can beperformed using i 1 and i 2 . where k is boltzman? constant. a four-measurementprocedure is adopted to improve accuracy by precisely measuring the ratio of i 1 and i 2 : 1) current i 1 is driven through the diode and the series resistor r, and the voltage across the diode is mea-sured as v be1 . 2) for the same current, the voltage across the diode and r is measured as v 1 . 3) repeat steps 1 and 2 with i 2 . i 1 is typically 4? and i 2 is typically 60? (see table 21). since only four integer numbers are accessible from theadc conversions at a certain voltage reference, the previ- ous equation can be represented in the following manner: where n v1 , n v2 , n vbe1 , and n vbe2 are the measure- ment results in integer format and v ref is the reference voltage used in the adc measurements. four-current method the four-current method is used to account for thediode series resistance and trace resistance. the four currents are defined as follows; i 1 , i 2 , m 1 i 1 , and m 2 i 2 . if the currents are selected so (m 1 - 1)i 1 = (m 2 - 1)i 2 , the effect of the series resistance is eliminated from thetemperature measurements. for the currents i 1 = 4? and i 2 = 60?, the factors are selected as m 1 = 16 and m 2 = 2. this results in the currents i 3 = m 1 i 1 = 64? and i 4 = m 2 i 2 = 120? (typ). as in the case of the two- current method, two measurements per current areused to improve accuracy by precisely measuring the values of the currents. 1) current i 1 is driven through the diode and the series resistor r, and the voltage is measured across thediode using the adc as nvbe1. 2) for the same current, the voltage across the diode and the series resistor is measured by the adc as nv1. t qn n nk nn nn v meas vbe vbe v vbe v vbe ref () ln = ? ? ? ? ? ? 21 11 22 16 2 t qv v nk i i meas be be ln = () ? ? ? ? ? ? 21 1 2 figure 13. temperature-sensor measurement block diagram current source 1:3 demux ival<1:0> imux<1:0> ain1ain2 ain1 ain2 temp+temp- programmable current source temp sensor downloaded from: http:///
3) repeat steps 1 and 2 with i 2 , i 3 , and i 4 . the measured temperature is defined as follows:where v ref is the reference voltage used and: external temperature sensor for an external temperature sensor, either the two-cur-rent or four-current method can be used. connect an external diode (such as 2n3904 or 2n3906) between pins ain1 and agnd (or ain2 and agnd). connect a sense resistor r between ain1 and ain2. maximize r so the ir drop plus v be of the p-n junction [(r x 60?)+v be ] is the smaller of the adc reference voltage or (av dd - 400mv). the same procedure as the internal temperature sensor can be used for the external tem-perature sensor, by routing the currents to ain1 (or ain2) (see table 20). for the two-current method, if the external diode? series resistance (r s ) is known, then the temperature measurement can be corrected as shown below: temperature-sensor calibration to account for various error sources during the temper-ature measurement, the internal temperature sensor is calibrated at the factory. the calibrated temperature equation is shown below: t a = g x t meas + b where g and b are the gain and offset calibration val-ues, respectively. these calibration values are available for reading from the temp_cal register. voltage reference and buffer an internal 1.25v bandgap reference has a buffer witha selectable 1.0v/v, 1.638v/v, or 2.0v/v gain, resulting in a respective 1.25v, 2.048v, or 2.5v reference voltage at ref. the adc and dac use this reference voltage. the state of the internal voltage reference output buffer at por is disabled so it can be driven, at ref, with an exter- nal reference between agnd and av dd . the reference has an initial tolerance of ?%. program the reference buffer through the serial interface. bypass ref with a4.7? capacitor to agnd. operational amplifiers (op amps) the max1359b includes two op amps. these op ampsfeature rail-to-rail outputs, near rail-to-rail inputs, and have an 80khz (1nf load) input bandwidth. the daca_op (dacb_op) register controls the power state of the op amps. when powered down, the outputs of the op amps are high impedance. single-pole/double-throw (spdt) switches the max1359b provides two uncommitted spdt switch-es. each switch has a typical on-resistance of 35 ? . control the switches through the sw_ctrl register, thepwm output, and/or a upio port configured to control the switches (upio1?pio4_ctrl register). pulse-width modulator (pwm) a single 8-bit pwm is available for various system taskssuch as lcd bias control, sensor bias voltage trim, buzzer drive, and duty-cycled sleep-mode power-con- trol schemes. pwm input clock sources include the 4.9512mhz fll output, the 32khz clock, and frequen- cy-divided versions of each. although most ?s have built-in pwm functions, the max1359b pwm is more flexible by allowing the upio outputs to be driven to dv dd or regulated cpout logic-high voltage levels. for duty-cycled power-control schemes, use the32khz-derived input clock. the pwm output is available independent of ? power state. the fll is typically dis- abled in sleep-override mode. serial interface the max1359b features a 4-wire serial interface consist-ing of a chip select ( cs ), serial clock (sclk), data in (din), and data out (dout). cs must be low to allow data to be clocked into or out of the device. dout is highimpedance while cs is high. the data is clocked in at din on the rising edge of sclk. data is clocked out atdout on the falling edge of sclk. the serial interface is compatible with spi modes cpol = 0, cpha = 0 and cpol = 1, cpha = 1. a write operation to the max1359b takes effect on the last rising edge of sclk. if cs goes high before the complete transfer, the write is ignored.every data transfer is initiated by the command byte. the command byte consists of a start bit (msb), r/ w bit, and 6 address bits. the start bit must be 1 to perform datatransfers to the device. zeros clocked in are ignored. for spi passthrough mode, see the upio_spi register . an address byte identifies each register. table 4 shows thecomplete register address map for this family of das. figures 14, 15, and 16 provide timing diagrams for read and write commands. tt nn nn nkin nn nn vr r actual meas v vbe v vbe v vbe v vbe ref s = ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 99 2 2211 21 11 16 () () m m nn nn nn nn v vbe v vbe v vbe v vbe 1 2 33 11 22 44 = ? ? ? ? ? ? ? ? ? ? ? ? t qn n qn n nkin m m v meas vbe vbe vbe vbe ref = () () ? ? ? ? ? ? 31 4 2 1 2 16 2 max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 31 downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 32 _________________________________________________ _____________________________________ cs sclk din dout x = dont care. 1 0 a5 a4 a3 a2 a1 a0 d n d n -1 d n-2 d n-3 d 2 d 1 d 0 x x figure 14. serial-interface register write with 8-bit control word, followed by a variable length data write cs sclk din dout 1 1 a5 a4 a3 a2 a1 a0 x x x x x x x x x d n d n-1 d n-2 d n-3 d 2 d 1 d 0 x = dont care. figure 15. serial-interface register read with 8-bit control word followed by a variable length data read cs sclk din dout 1 0 a4 a3 a2 a1 drdy d0 a0 d7 d6 d5 d4 d3 d2 d1 x d0 d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 d5 d4 d3 d2 d1 1 1 a4 a3 a2 a1 a0 x adcconv changes x = dont care. figure 16. performing an adc conversion ( drdy function can be accessed at upio pins) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 33 register name start ctl (r/ w ) adr<5:0> (address) d<39:0>, d<23:0>, d<15:0> or d<7:0> (data) adce strt bip pol cont adcref gain<1:0> adc 1r / w 00000x rate<2:0> mode<2:0> x x mux 1r / w 00001s muxp<3:0> muxn<3:0> data 1 r 00010x adc<15:0> offset cal 1r / w 00011x offset<23:0> gain cal 1r / w 00100x gain<23:0> reserved 1r / w 00101x reserved. do not use. dae/ op3e dbe/ op2e op1e x x x daca<9:8> daca_op 1r / w 00110x daca<7:0> dae/ op3e dbe/ op2e op1e x x x dacb<9:8> dacb_op 1r / w 00111x dacb<7:0> ref_sdc 1r / w 01000x refv<1:0> aoff aon sdce tsel<2:0> asec<19:4> al_day 1r / w 01001x asec<3:0> x x x x reserved 1r / w 01010x reserved. do not use. awe ade x rwe rtce osce flle hfce clk_ctrl 1r / w 01011x cksel<2:0> io32e ck32e clke intp wde sec<31:0> rtc 1r / w 01100x sub<7:0> pwme fsel<2:0> swah swal reser ved reser ved pwm_ctrl 1r / w 01101x spd1 spd2 x x x x x x pwmth<7:0> pwm_thtp 1r / w 01110x pwmtp<7:0> watchdog 1 w 01111x x x x x x x x x norm_md 1 w 10000x x x x x x x x x sleep 1 w 10001x x x x x x x x x sleep_cfg 1r / w 10010slp sosce s c k 32e s p w m e shdn x x x x upio4_ctrl 1r / w 10011x up4md<3:0> pup4 sv4 alh4 ll4 upio3_ctrl 1r / w 10100x up3md<3:0> pup3 sv3 alh3 ll3 upio2_ctrl 1r / w 10101x up2md<3:0> pup2 sv2 alh2 ll2 upio1_ctrl 1r / w 10110x up1md<3:0> pup1 sv1 alh1 ll1 upio_spi 1r / w 10111x up4s up3s up2s up1s x x x x sw_ctrl 1r / w 11000xswa spdt1<1:0> spdt2<1:0> x x temp_ctrl 1r / w 11001x imux<1:0> ival<1:0> x x x x temp_cal 1 r 11010x tgain<7:0> toffs<5:0> x x mldvd mlcpd mado msdc mcrdy madd mald x imsk 1r / w 11011x mupr<4:1> mupf<4:1> reserved 1r / w 11100x reserved. do not use. ps_vmons 1r / w 11101x ldoe cpe lsde cpde hyse rste x x reserved 1r / w 11110x reserved. do not use. ldvd lcpd adou sdc crdy add ald x status 1 r 11111x upr<4:1> upf<4:1> register definitions table 4. register address map x = don? care. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 34 _________________________________________________ _____________________________________ msb lsb adce strt bip pol cont adcref gain<1:0> rate<2:0> mode<2:0> x x adc register (power-on state: 0000 0000 0000 00xx) register bit descriptions the adc register configures the adc and startsa conversion. adce: adc power-enable bit. adce = 1 powers up the adc, and adce = 0 powers down the adc. strt: adc start bit. strt = 1 resets the registers inside the adc filter and initiates a conversion or cali-bration. the conversion begins immediately after the 16th adc control bit is clocked by the rising edge of sclk. the initial conversion requires four conversion cycles for valid output data. if cont = 0 when strt is asserted, the adc stops after a single conversion and holds the result in the data register. if cont = 1 when strt is asserted, the adc performs continuous conver- sions at the rate specified by the rate<2:0> bits until cont is deasserted or adce is deasserted, powering down the adc. the strt bit is automatically deasserted after the initial conversion is complete (four conversion cycles, the adc status bit add in the status register asserts.) the current adc configurations are not affect- ed if the adc register is written with strt = 0. this allows the adc and mux configurations to be updated simultaneously with the s bit in the mux register. bip: unipolar/bipolar bit. set bip = 0 for unipolar mode and bip = 1 for bipolar mode. unipolar-mode data isunsigned binary format and bipolar is two? complement. see the adc transfer functions section for more details. pol: polarity flipper bit. pol = 1 flips the polarity of the differential signal to the adc and the input to the signal-detect comparator (sdc). pol = 0 sets the positive mux output to the positive adc and sdc inputs, and the neg- ative mux output to the negative adc and sdc inputs. pol = 1 sets the positive mux output to the negative adc and sdc inputs, and the negative mux output tothe positive adc and sdc inputs. cont: continuous conversion bit. cont = 1 enables continuous conversions following completion of the firstconversion or calibration(s) initiated by the strt or s bit. set cont = 0 while asserting the strt bit, or prior to asserting the s bit to perform a single conversion or to prevent conversions following a calibration. set cont = 0 to abort continuous conversions already in progress. when the adc is stopped in this way, the last complete conversion result remains in the data register and the internal adc state information is lost. asserting the cont bit does not restart the adc, but results in contin- uous conversions once the adc is restarted with the strt or s bit. adcref: adc reference source bit. set adcref = 0 to select ref as the adc reference. set adcref = 1to select av dd as the adc reference. to measure the av dd voltage without having to attenuate the supply voltage, select ref and agnd as the differential inputsto the adc, with pol = 0 and while adcref = 1. gain<1:0>: adc gain-setting bits. these two bits select the gain of the adc as shown in table 5. gain setting (v/v) gain1 gain0 100 201 410 811 table 5. setting the gain of the adc downloaded from: http:///
-rate<2:0>: adc conversion-rate-setting bits. these three bits set the conversion rate of the adc as shownin table 6. the initial conversion requires four conver- sion cycles for valid data and subsequent conversions require only one cycle (if cont = 1). a full-scale input change can require up to five cycles for valid data if the digital filter is not reset with the strt or s bit. mode<2:0>: conversion-mode bits. these three bits determine the type of conversion for the adc as shownin table 7. when the adc finishes an offset calibration and/or gain calibration, the mode<2:0> bits clear to 0 hex, the add bit in the status register asserts, and an interrupt asserts on int (or upio_ if programmed as drdy) if madd is unmasked. perform a gain calibra- tion after achieving the desired offset (calibrated or not). if an offset and gain calibration are performed together (mode<2:0> = 7 hex), the offset calibration is performed first followed by the gain calibration, and the ? is interrupted by int (or upio_ if programmed as drdy) if madd is unmasked only upon completion of both offset and gain calibration. after power-on or cali- bration, the adc does not begin conversions until initi- ated by the user (see the adce and strt bit descriptions in this section and see the s bit descrip- tions in the mux register section). see the gain cal register and offset cal register sections for details on system calibration. max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 35 nominal continuousconversion rate (sps) decimation ratio actual continuousconversion rate (sps) 10 1096 10.01042142 40 274 40.04168568 50 220 49.87009943 60 183 59.953125 200 55 199.4803977 240 46 238.5091712 400 27 406.3489583 512 23 477.0183424 continuousconversion rate (sps) single conversion rate (sps) rate2 rate1 rate0 10 2.5 0 0 0 40 10 0 0 1 50 12.5 0 1 0 60 15 0 1 1 200 50 1 0 0 240 60 1 0 1 400 100 1 1 0 512 128 1 1 1 table 6. setting the adc conversion rate* *calculate the adc sampling rate using the followingequation: where f hfclk = 4.9152mhz nominally. f f decimation ratio s hfclk = 448 the actual rates are: conversion mode mode2 mode1 mode0 normal 0 0 0 system offset calibration 0 0 1 system gain calibration 0 1 0 normal 0 1 1 normal 1 0 0 self offset calibration 1 0 1 self gain calibration 1 1 0 self offset and gaincalibration 111 table 7. setting the adc conversion mode downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 36 _________________________________________________ _____________________________________ the mux register configures the positive and negativemux inputs and can start an adc conversion. s (adr0): conversion start bit. the s bit is the lsb of the mux register address byte. s = 1 resets the regis- ters inside the adc filter and initiates a conversion or calibration. the conversion begins immediately after the eighth mux register data bit, when s = 1 and when writing to the mux register. this allows the new mux and adc register settings to take effect simultaneously for a new conversion, if strt = 0 during the last write to the adc register. if the s bit is asserted and the command is a read from the mux register, the conver- sion starts immediately after the s bit (adr0) is clocked in by the rising edge of sclk. read the mux register with s = 1 for the fastest method of initiating a conversion because only 8 bits arerequired. the subsequent mux register read is valid, but can be aborted by raising cs with no harmful side effects. the initial conversion requires four conversioncycles for valid output data. if cont = 0 and s = 1, the adc stops after a single conversion and holds the result in the data register. if cont = 1 and s = 1, the adc performs continuous conversions at the rate spec- ified by the rate<2:0> bits until cont deasserts oradce deasserts, powering down the adc. when a conversion initiates using the s bit, the strt bit asserts and deasserts automatically after the initial conversion completes. writing to the mux register with s = 0 caus- es the mux settings to change immediately and the adc continues in its prior state with its settings unaf- fected. when the adc is powered down, mux inputs are open. muxp<3:0>: mux positive input bits. these four bits select one of ten inputs from the positive mux to go to the positive output of the mux as shown in table 8. any writes to the mux register take effect immediately once the lsb (muxn0) is clocked by the rising edge of sclk. muxn<3:0> mux negative input bits. these four bits select one of ten inputs from the negative mux to go to the negative output of the mux as shown in table 9. any writes to the mux register take effect immediately once the lsb (muxn0) is clocked by the rising edge of sclk. the data register contains the data from the most recently completed conversion. msb lsb s (adr0) muxp3 muxp2 muxp1 muxp0 muxn3 muxn2 muxn1 muxn0 mux register (power-on state: 0000 0000) positive mux input muxp3 muxp2 muxp1 muxp0 ain1 0 0 0 0 sno1 0 0 0 1 fba 0 0 1 0 scm1 0 0 1 1 in2- 0 1 0 0 snc1 0 1 0 1 in1- 0 1 1 0 temp+ 0 1 1 1 ref 1 0 0 0 agnd 1 0 0 1 101x open 11xx table 8. selecting the positive mux inputs x = don? care. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 37 negative mux input muxn3 muxn2 muxn0 muxn0 temp- 0 0 0 0 sno2 0 0 0 1 outa 0 0 1 0 scm2 0 0 1 1 out2 0 1 0 0 snc2 0 1 0 1 out1 0 1 1 0 ain2 0 1 1 1 ref 1 0 0 0 agnd 1 0 0 1 101x open 11xx table 9. selecting the negative mux inputs x = don? care. msb adc15 adc14 adc13 adc12 adc11 adc10 adc9 adc8 lsb adc7 adc6 adc5 adc4 adc3 adc2 adc1 adc0 data register (power-on state: 0000 0000 0000 0000) adc<15:0> analog-to-digital conversion data bits. these 16 bits are the results from the most recently completed conversion. the data format is unsigned, binary for unipolar mode, and two? complement for bipolar mode. msb offset23 offset22 offset21 offset20 offset19 offset18 offset17 offset16 offset15 offset14 offset13 offset12 offset11 offset10 offset9 offset8 lsb offset7 offset6 offset5 offset4 offset3 offset2 offset1 offset0 offset cal register (power-on state: 0000 0000 0000 0000 0000 0000 ) the offset cal register contains the 24-bit data ofthe most recently completed offset calibration. offset<23:0>: offset-calibration bits. the data format is two? complement and is subtracted from the adcoutput before being written to the data register. the offset calibration allows input offset errors between v ref ?0% to be corrected in unipolar or bipolar mode. the max1359b can perform system offset calibration or self offset calibration. self-calibration performs a cali-bration for the entire signal path. see the adc calibration section for more details. the adc input voltage range specifications must always be obeyed and the offset cal register effec-tively offsets the adc digital scale to a ?ero?value determined by the calibration. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 38 _________________________________________________ _____________________________________ msb gain23 gain22 gain21 gain20 gain19 gain18 gain17 gain16 gain15 gain14 gain13 gain12 gain11 gain10 gain9 gain8 lsb gain7 gain6 gain5 gain4 gain3 gain2 gain1 gain0 gain cal register (power-on state: 1000 0000 0000 0000 0000 0000) gain<23:0>: gain-calibration bits. the data format is unsigned binary with 23 bits to the right of the decimalpoint and scales the adc output before being written to the data register. the gain calibration allows full-scale errors between -v ref / 2 and +v ref / 2 to be corrected in unipolar mode, and full-scale errors between (+50%x v ref ) and (+200% x v ref ) in unipolar or bipolar mode. the max1359b can perform system gain cali-bration or self gain calibration. self-calibration performs a calibration for offsets in the adc and system calibra-tion performs a calibration for the entire signal path. see the adc calibration section for more details. the adc input voltage range specifications must always be obeyed and the gain cal register effectively scalesthe adc digital output to a full-scale value determined by the calibration. the usable gain-calibration range is limited to less than the full gain cal register digital- scaling range by the internal noise of the adc. daca_op register writing to the daca_op output register updates daca on the rising sclk edge of the lsb data bit. the output voltage can be calculated as follows: v outa = v ref x n / 2 10 wherev ref is the reference voltage for the dac. n is the integer value of daca<9:0> output register.the output buffer is in unity gain. the daca data is 10 bits long and right justified. dae: daca enable bit. set dae = 1 to power up the daca and the daca output buffer in the max1359b. op2e: op2 power-enable bit. set op2e = 1 to power up op2. op1e: op1 power-enable bit. set op1e = 1 to power up op1. daca<9:0>: daca data bits. msb dae op2e op1e x x x daca9 daca8 lsb daca7 daca6 daca5 daca4 daca3 daca2 daca1 daca0 daca_op register (power-on state: 000x xx00 0000 0000) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 39 the ref_sdc register contains bits to control the refer-ence voltage and signal-detect comparator. refv<1:0>: reference buffer voltage gain and enable bits. enables the output buffer, sets the gain and thevoltage at the ref pin as shown in table 10. power-on state is off to enable an external reference to drive the ref pin without contention. aoff: adc and dac/op-amp power-off bit. this bit pro- vides a method for turning off several analog functionswith a single write. setting aoff = 1 deasserts the adce in the adc register and dae/op3e, dbe/op2e, and op1e bits in the daca_op and dacb_op regis- ters, powering down these analog blocks. setting aoff = 0 has no effect. the aon bit has priority when both aon and aoff bits are asserted. most of the analog functions can be disabled with a single write to the ref_sdc register by using aoff, refv<1:0>, and sdce. aon: adc and dac/op-amp power-on bit. this bit provides a method of turning on several analog func-tions with a single write. setting aon = 1 asserts the adce bit in the adc register and dae/op3e, dbe/op2e, and op1e bits in the daca_op and dacb_op registers, powering up these blocks. setting aon = 0 has no effect. the aon bit has priority when both aon and aoff bits are asserted. most of the analog functions can be enabled with a sin- gle write to the ref_sdc register using aon, refv<1:0>, and sdce. sdce: signal-detect comparator power-enable bit. set sdce = 1 to power up the signal-detect comparatorand set sdce = 0 to power down the signal-detect comparator. the adce bit in the adc register must be set to 1 to use the signal-detect comparator. tsel<2:0>: threshold-select bits. these bits select the threshold for the signal-detect comparator as shown intable 11. msb lsb refv1 refv0 aoff aon sdce tsel2 tsel1 tsel0 ref_sdc register (power-on state: 0000 0000) reference buffer gain (v/v) ref output voltage (v) refv1 refv0 disabled off (high impedance at ref) 00 1.0 1.25 0 1 1.638 2.048 1 0 2.0 2.5 1 1 table 10. setting the reference output voltage nominal threshold (mv) tsel2 tsel1 tsel0 00xx 5 0 100 100 1 0 1 150 1 1 0 200 1 1 1 table 11. setting the signal-detect comparator threshold x = don? care. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 40 _________________________________________________ _____________________________________ the al_day register stores the second information ofthe time-of-day alarm. asec<19:0 > : alarm-second bits. these 20 bits store the time-of-day alarm, which corresponds to the lower20 bits of the rtc second counter or sec<19:0>. program the time-of-day alarm trigger between 1s to just over 12 days beyond the current rtc second counter value in increments of 1s. assert the awe bit in the clk_ctrl register (see the clk_ctrl register section) to enable writing to the al_day register. enabling the time-of-day alarm requirestwo writes to the clk_ctrl register. write the 20 alarm- second bits in 3 bytes, msb first. if cs is raised before the lsb is written, the alarm write is aborted, and theexisting value remains. when the lower 20 bits in the rtc second counter match the contents of this register, thealarm triggers and asserts ald in the status register. it also asserts an interrupt on the int pin unless masked by the mald bit in the imsk register. the part enters normal mode if an alarm triggers while in sleep mode. the time- of-day alarm is intended to trigger single events. therefore, once it triggers, in the clk_ctrl register, the ade bit is automatically cleared, disabling the time-of- day alarm. implement a recurring alarm with repeated software writes over the serial interface each time the time-of-day alarm triggers. the time-of-day alarm can also be programmed to output at the upio pins. when configured this way the mald bit does not mask the upio alarm output. msb asec19 asec18 asec17 asec16 asec15 asec14 asec13 asec12 asec11 asec10 asec9 asec8 asec7 asec6 asec5 asec4 lsb asec3 asec2 asec1 asec0 x x x x al_day register (power-on state: 0000 0000 0000 0000 0000 xxxx) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 41 msb awe ade x rwe rtce osce flle hfce lsb cksel2 cksel1 cksel0 io32e ck32e clke intp wde clk_ctrl register (power-on state: 00x0 1111 0010 1110) the clk_ctr register contains the control bits for thertc alarms and clocks. awe: alarm write-enable bit. set awe = 1 to write data to the al_day register as well as the ade bit in thisregister. when awe = 0, all writes are prevented to the al_day register and the ade bit in this register. a sec- ond write to this register is required to change the value of the ade bit. the power-on default state is 0. ade: alarm (time-of-day) enable bit. set ade = 1 to enable the time-of-day alarm and set ade = 0 to dis-able the time-of-day alarm. when enabled, the ald bit in the status register asserts when the rtc second counter time matches al_day register. the device wakes up from sleep to normal mode if not already awake. the ade bit can only be written if the awe = 1 from a previous write. the power-on default state is 0. rwe: rtc write-enable bit. set rwe = 1 prior to writing to the rtc register and the rtce bit in this register. ifrwe = 0, all writes are prevented to the rtc register as well as the rtce bit in this register. the rwe signal takes effect after the rising edge of the 16th clock; therefore, a second write to this register is required tochange the value of the rtce bit. the power-on default state is 0. rtce: real-time-clock enable bit. set rtce = 1 to enable the rtc, and set rtce = 0 to disable the rtc.the rtc has a 32-bit second and an 8-bit subsecond counter. the power-on default state is 1. osce: 32khz crystal-oscillator enable bit. set osce = 1 to power up the 32khz oscillator and set osce = 0 topower down the oscillator. the power-on default state is 1. flle: frequency-locked-loop enable bit. set flle = 1 to enable the fll, and set flle = 0 to disable the fll.if hfce = 1 and flle = 0, the internal high-frequency oscillator is enabled but it is not frequency-locked to the 32khz clock. when flle is asserted, it typically takes 3.5ms for the high-frequency clock to settle to within 1% of the 32khz reference clock frequency. switching the fll on or off with this bit does not cause high-frequency clock glitching. the power-on default state is 1. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 42 _________________________________________________ _____________________________________ hfce: high-frequency-clock enable bit. set hfce = 1 to enable the internal high-frequency clock source, andset hfce = 0 to disable the high-frequency clock source. if hfce = 1 and clke = 1, the internal high-frequency oscillator is enabled and is present at clk. the power- on default state is 1. cksel<2:0>: clock selection bits. these bits select the fll-based output clock frequency at the high-fre-quency clk pin as shown in table 12. the power-on default state is 001. io32e: input/output 32khz clock select bit. set io32e = 0 to configure the clk32k pin as an output and setio32e = 1 to configure the clk32k pin as an input, regardless of the signal on the 32kin pin as shown in table 13. external clock frequencies applied to clk32k are clock sources to the fll, charge pump, and the signal- detect comparator. the default power-on state is 0. ck32e: clk32k output-buffer enable bit. set ck32e = 1 to enable the clk32k output buffer as long as osce= 1 and io32e = 0, otherwise the ck32e bit will not be asserted. set ck32e = 0 to disable the clk32k output buffer. the power-on default state is 1. clke: clk output-buffer enable bit. set clke = 1 to enable the clk output buffer. set clke = 0 to disablethe buffer. disabling the buffer is useful for saving power in cases where the high-frequency clock is usedinternally but is not needed externally. if hfce = 0, or if clke = 0, clk remains low. the power-on default state is 1. intp: interrupt pin polarity bit. set intp = 1 to make int an active-high output when asserted and set intp= 0 to make int an active-low output when asserted. the power-on default state is 1. wde: watchdog-enable bit. set wde = 1 to enable the watchdog timer, which asserts reset low within 500ms if the watchdog register is not written. set wde = 0to disable the watchdog timer. the power-on default state is 0. clock frequency (khz) cksel2 cksel1 cksel0 4915.2 0 0 0 2457.6 0 0 1 1228.8 0 1 0 614.4 0 1 1 32.768 1 0 0 16.384 1 0 1 8.192 1 1 0 4.096 1 1 1 table 12. setting the clk frequency clk32k clk32k io32e 32kin, 32kout rtc, pwm, wdt clock source fll, c/p, sdc input source adc clock source output 1 0 xtal attached xtal xtal fll/hfclk input 0 1 xtal attached xtal clk32k fll/hfclk table 13. configuring the clk32k as an input or output downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 43 the rtc register stores the 40-bit second and subsec-ond count of the respective time-of-day and system clocks. sec<31:0>: the second bits store the time-of-day clock settings. it is a 32-bit binary counter with 1s reso-lution that can keep time for a span of over 136 years. firmware in the ? can translate this time count to units that are meaningful to the system (i.e., translate to cal- endar time or as an elapsed time from some predefined time = 0, such as january 1, 2000). the rtc runs con- tinuously as long as rtce = 1 (see the clk_cntl register section) and does not stop for reads or writes. the counter increments when the subsecond counteroverflows. set rwe = 1 to enable writing to the rtc register. after writing to rwe, perform another write and set rtce = 1 to enable the rtc. a 40-bit burst write operation, starting with sec31 and finishing with sub0 is required to set the rtc second and subsec- ond bits. if cs is brought high before the 40th rising sclk edge, the write is aborted and the rtc contentsare unchanged. the rtc register is loaded on the ris- ing sclk edge of the 40th bit (sub0). a 40-bit burst read operation, starting with sec31 and finishing with sub0, is required to retrieve the current rtc second and subsecond counts. the read command can be aborted prior to receiving the 40th bit (sub0) by raising cs and any rtc data read to that point is valid. when the read command is received, a snapshot of a validrtc second count is latched to avoid reading an erro- neous, transitioning rtc value. due to the asynchro- nous nature of rtc reads, it is possible to have a maximum 1s error between the actual and reported times from the time-of-day clock. to prevent the data from changing during a read operation, complete reads of the rtc register in less than 1ms. the power-ondefault state is 0000 0000 hex. sub<7:0>: the subsecond bits store the system clock. this 8-bit binary counter has 3.9ms resolution (1/256hz)and a span of 1s. the subsecond counter increments in single counts from 00 hex to ff hex before rolling over again to 00 hex, at which time, the rtc second counter (sec<31:0>) increments. the rtc runs continuously (as long as rtce = 1) and does not stop for reads or writes. a 256hz clock, derived from the 32khz crystal, increments this counter. set the rwe = 1 bit to enable writing to the rtc register. after writing to rwe, perform another write, setting rtce = 1, to enable the rtc. a 40-bit burst write operation, starting with sec31 and fin- ishing with sub0, is required to set the rtc second and subsecond bits. if cs is brought high before the 40th rising sclk edge, the write is aborted and the rtc con-tents are unchanged. the rtc register is loaded on the rising sclk edge of the 40th bit (sub0). a 40-bit burst read operation, starting with sec31 and finishing with sub0, is required to retrieve the current rtc second and subsecond counts. the read command can be aborted prior to receiving the 40th bit (sub0) by raising cs and any rtc data read to that point is valid. when the read command is received, a snapshot of a validrtc second count is latched to avoid reading an erro- neous, transitioning rtc value. due to the asynchro- nous nature of rtc reads, it is possible to have a maximum 1s error between the actual and reported times from the time-of-day clock. to prevent the data from changing during a read operation, complete reads of the rtc registers occur in less than 1ms. the power- on default state is 00 hex. msb sec31 sec30 sec29 sec28 sec27 sec26 sec25 sec24 sec23 sec22 sec21 sec20 sec19 sec18 sec17 sec16 sec15 sec14 sec13 sec12 sec11 sec10 sec9 sec8 sec7 sec6 sec5 sec4 sec3 sec2 sec1 sec0 lsb sub7 sub6 sub5 sub4 sub3 sub2 sub1 sub0 rtc register (power-on state: 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 44 _________________________________________________ _____________________________________ the pwm_ctrl register contains control bits for the 8-bit pwm. pwme: pwm-enable bit. set pwme = 1 to enable the internal pwm and set pwme = 0 to disable the internalpwm. enable the high frequency clock before enabling the pwm when using input clock frequencies above 32.768khz. the power-on default state is 0. fsel<2:0>: frequency selection bits. selects the pwm input clock frequency as shown in table 14. thepower-on default is 000. swah: swa-switch pwm-high control bit. set swah = 1 to enable the pwm output to directly control the swaswitch. when swah = swal, the pwm output is dis- abled from controlling the swa switch. when swah = 1, a pwm high output closes the swa switch and a pwm low output opens the swa switch. the pwm high output refers to the beginning of the period when the output is logic-high. see table 17 for more details. the power-on default is 0. swal: swa-switch pwm-low control bit. set swal = 1 to enable the inverted pwm output to directly control the swa switch. when swah = swal , the pwm output is disabled from controlling the swa switch. whenswal = 1, a pwm low output closes the swa switch and a pwm high output opens the swa switch. the pwm low output refers to the end of the period when the output is logic-low. see table 17 for more details. the power-on default is 0. spd1: spdt1-switch pwm drive control bit. set spd1 = 1 to enable the pwm output to directly control thespdt1 switch and set spd1 = 0 to disable the pwm output controlling the spdt1 switch. the spdt1<1:0> bits, the upio pins (if programmed), and the pwm out- put (if enabled), determine the spdt1-switch state. see table 18 for more details. the power-on default is 0. spd2: spdt2-switch pwm drive control bit. set spd2 = 1 to enable the pwm output to directly control thespdt2 switch and set spd2 = 0 to disable the pwm output controlling the spdt2 switch. the spdt2<1:0> bits, the upio pins (if programmed), and the pwm out- put (if enabled), determine the spdt2-switch state. see table 19 for more details. the power-on default is 0. msb pwme fsel2 fsel1 fsel0 swah swal reserved reserved lsb spd1 spd2 x x x x x x pwm_ctrl register (power-on state: 0000 0000 00xx xxxx) pwm input frequency* (khz) fsel2 fsel1 fsel0 4915.2** 0 0 0 2457.6** 0 0 1 1228.8** 0 1 0 32.768 0 1 1 8.192 1 0 0 1.024 1 0 1 0.256 1 1 0 0.032 1 1 1 table 14. setting the pwm frequency * the lower pwm frequencies are useful for power-supply duty cycling to conserve battery life and enable a single battery cell-powered sys- tem. the higher frequencies allow reasonably small, external components for rc filtering when used as a dac for bias adjustment s. ** when the part is in sleep mode, the hfck is shut down. in this case, pwm frequencies above 32khz are not available (see spwme in the sleep_cfg register section). downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 45 the pwm_thtp register contains the bits that set thepwm on-time and period. pwmth<7:0>: pwm time high bits. these bits define the pwm on (or high) time and when combined with thepwmtp<7:0> bits, they determine the duty cycle and period. the on-time duty cycle is defined as: (pwmth<7:0> + 1) / (pwmtp<7:0> + 1) to get 50% duty cycle, set pwmth<7:0> to 127 deci-mal and pwmtp<7:0> to 255 decimal. a 100% duty cycle (i.e., always on) is possible with a value of pwmth<7:0> pwmtp<7:0> > 0. a 0% duty cycle is possible by setting pwmth<7:0> = 0 or pwme = 0 inthe pwm_ctrl register. if the pwm is selected to drive the upio_ pin(s), the alh_ bit(s) (upio_ctrl register) determine the on-time polarity at the beginning of the pwm cycle. if alh_= 1, the on-time at the start of the pwm period causes a logic-high level (dv dd or cpout) at the upio_ pin and when alh_= 0, it causesa logic-low level (dgnd) during the on-time. when the pwm output drives the swa/b switches, the swa(b)h or swa(b)l bits in the pwm_ctrl register, determine which pwm phase closes these switches. the spdt1 and spdt2 switches do not have pwm polarity inver- sion bits (see the spdt1<1:0> and spdt2<1:0> bit descriptions in the sw_ctrl register section) but their effective polarity is set by how the switches are con-nected externally. the power-on default is 00 hex. pwmtp<7:0>: pwm time period bits. these bits con- trol the pwm output period defined. the pwm outputperiod is defined as: (pwmtp<7:0> + 1) / (pwm input frequency) set the pwm input frequency by selecting thefsel<2:0> bits as described in table 14. the power- on default is 00 hex. watchdog register (power-on state: n/a) writing to the watchdog register address sets thewatchdog timer to 0ms. if the watchdog is enabled (wde = 1) and the watchdog register is not written to before the 750ms expiration, reset asserts low for 250ms and the watchdog timer restarts at 0ms whenthe watchdog timer is enabled. there are no data bits for this register and the watchdog timer is reset on the rising edge of sclk during the adr0 bit in the watchdog register address control byte. figure 17 shows an example of watchdog timing. norm_md register (power-on state: n/a) exit sleep mode and enter normal mode by writing tothe norm_md register. the specific normal-mode state of all circuit blocks is set by the user, who must configure the individual power-enable bits before enter- ing sleep mode (table 15). there are no data bits for this register and normal mode begins on the rising edge of sclk during the adr0 bit in the norm_md register address control byte. sleep register (power-on state: n/a) enter sleep mode by writing to the sleep register. thislow-power state overrides most of the normal power- control bits. table 15 shows which functions are off, which functions are unaffected (ade, rtce, lsde, and hyse), and which functions are controlled by special sleep-mode bits (sosce, sck32e, and spwme) while in sleep mode. there are no data bits for this register and sleep mode begins on the rising edge of sclk during the adr0 bit in the sleep register address con- trol byte. msb pwmth7 pwmth6 pwmth5 pwmth4 pwmth3 pwmth2 pwmth1 pwmth0 lsb pwmtp7 pwmtp6 pwmtp5 pwmtp4 pwmtp3 pwmtp2 pwmtp1 pwmtp0 pwm_thtp register (power-on state: 0000 0000 0000 0000) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 46 _________________________________________________ _____________________________________ register name circuit block description por default normal mode sleep adc adc adce = 0 adce off daca/op3 dae/op3e = 0 dae/op3e off dacb/op2 dbe/op2e = 0 dbe/op2e off daca_op, dacb_op op1 op1e = 0 op1e off reference buffer gain and enable refv<1:0> = 00 refv<1:0> off ref_sdc signal-detect comparator sdce = 0 sdce off time-of-day alarm enable ade = 0 ade ade rtc rtce = 1 rtce rtce ck32 xtal oscillator osce = 1 osce sosce ck32 output buffer ck32e = 1 ck32e sck32e high-frequency clock hfce = 1 hfce off high-frequency clock output buffer clke = 1 clke off fll enable flle = 1 flle off clk_ctrl watchdog timer wde = 0 wde off pwm_ctrl pwm pwme = 0 pwme spwme linear regulator ldoe = 0 ldoe off charge-pump doubler cpe = 0 cpe off cpout voltage monitor cpde = 0 cpde off 1.8v dv dd monitor lsde = 1 lsde lsde ps_vmons 1.8v monitor hysteresis hyse = 0 hyse hyse temp_ctrl temperature sense source imux<1:0> = 00 imux<1:0> off upio_ function up_md<3:0> = 0 hex up_md<3:0> up_md<3:0> upio_ pullup pup_ = 1 pup_ pup_ upio_ supply voltage sv_ = 0 sv_ sv_ upio_ctrl upio_ assertion level alh_ = 0 alh_ alh_ table 15. normal-mode and sleep-register summary downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 47 the sleep_cfg register allows users to program spe-cific behavior for the 32khz oscillator, buffer, and pwm in sleep mode. it also contains a sleep-control bit (slp) to enable sleep mode. slp (adr0): sleep bit. the slp bit is the lsb in the sleep_cfg address control byte. set slp = 1 toassert the shdn bit and enter sleep mode. writing the register with slp = 0 or reading with slp = 0 or slp = 1 has no effect on the shdn bit. sosce: sleep mode 32khz crystal oscillator enable bit. sosce = 1 enables the 32khz oscillator in sleepmode and sosce = 0 disables it in sleep mode, regardless of the state of the osce bit. the power-on default is 1. sck32e: sleep-mode ck32k-pin output-buffer enable bit. sck32e = 1 enables the 32khz output buffer insleep mode and sck32e = 0 disables it in sleep mode, regardless of the state of the ck32e bit. the power-on default is 1. spwme: sleep mode pwm enable bit. spwme = 1 enables the internal pwm in sleep mode and spwme =0 disables it in sleep mode, regardless of the state of the pwme bit. input frequencies are limited to 32.768khz or lower since the high-frequency clock is disabled in sleep mode. sosce must be asserted to have 32khz avail- able as an input to the pwm. the power-on default is 0. shdn: shutdown bit. this bit is read only. shdn is asserted by writing to the sleep register address or bywriting to the sleep_cfg register with slp = 1. when shdn is asserted, the device is in sleep mode even if the sleep or sleep function on the upio is deassert- ed. the shdn bit is deasserted by writing to thenorm_md register or by other defined events. events that cause shdn to be deasserted are a day alarm or an edge on the upio wake-up pin causing wake-up to be asserted. the power-on default is 0. msb lsb slp (adr0) sosce sck32e spwme shdn x x x x sleep_cfg register (power-on state: 1100 xxxx) 4hz clock 2-bit counter x wde = 1 012 3 reset watchdog address 01 2 watchdog address watchdog address 01 0120 750ms 250ms spi writes d q q r ck dq q r ck divide- by-8192 32k wde por wdw watchdog timer 4hz reset figure 17. watchdog timer architecture downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 48 _________________________________________________ _____________________________________ upio3_ctrl register. this register configures theupio3 pin functionality. up3md<3:0>: upio3-mode selection bits. these bits configure the mode for the upio3 pin. see table 16 fora detailed description. the power-on default is 0 hex. pup3: pullup upio3 control bit. set pup3 = 1 to enable a weak pullup resistor on the upio3 pin and setpup3 = 0 to disable it. the pullup resistor is connected to either dv dd or cpout as programmed by the sv3 bit. the pullup is enabled only when upio3 is config-ured as an input. op en-drain behavior can be simulated at upio3 by setting the mode to gpo with ll3 = 0 andby changing the mode to gpi with pup3 = 0, allowing external high pullup. the power-on default is 1. sv3: supply-voltage upio3 selection bit. set sv3 = 0 to select dv dd as the supply voltage for the upio3 pin and set sv3 = 1 to select cpout as the supply volt-age. the selected supply voltage applies to all modes for the upio3 pin. the power-on default is 0. alh3: active logic-level assertion high upio3 bit. set alh3 = 0 to define the input or output assertion levelfor upio3 as low except when in gpi and gpo modes and set alh3 = 1 to define the input or output assertion level as high. for example, asserting alh3 defines the upio3 output signal as alarm, while deasserting alh3 defines it as alarm . similarly, asserting alh3 defines the upio3 input signal as wu, while deassert-ing alh3 defines it as wu . the power-on default is 0. ll3: logic-level upio3 bit. when upio3 is configured as gpo, ll3 = 0 sets the output to a logic-low and ll3= 1 sets the output to a logic-high. a read of ll3 returns the voltage level at the upio3 pin at the time of the read regardless of how it is programmed. the power-on default is 0. upio4_ctrl register. this register configures theupio4 pin functionality. up4md<3:0>: upio4-mode selection bits. these bits configure the mode for the upio4 pin. see table 16 fora detailed description. the power-on default is 0 hex. pup4: pullup upio4 control bit. set pup4 = 1 to enable a weak pullup resistor on the upio4 pin and set pup4 =0 to disable it. the pullup resistor is connected to either dv dd or cpout as programmed by the sv4 bit. the pullup is enabled only when upio4 is configured as aninput. open-drain behavior can be simulated at upio4 by setting the mode to gpo with ll4 = 0 and by chang- ing the mode to gpi with pup4 = 0, allowing external high pullup. the power-on default is 1. sv4: supply-voltage upio4 selection bit. set sv4 = 0 to select dv dd as the supply voltage for the upio4 pin and set sv4 = 1 to select cpout as the supply volt-age. the selected supply voltage applies to all modes for the upio4 pin. the power-on default is 0. alh4: active logic-level assertion high upio4 bit. set alh4 = 0 to define the input or output assertion levelfor upio4 as low except when in gpi and gpo modes. set alh4 = 1 to define the input or output assertion level as high. for example, asserting alh4 defines the upio4 output signal as alarm, while deasserting alh4 defines it as alarm . similarly, asserting alh4 defines the upio4 input signal as wu, while deassert-ing alh4 defines it as wu . the power-on default is 0. ll4: logic-level upio4 bit. when upio4 is configured as gpo, ll4 = 0 sets the output to a logic-low and ll4= 1 sets the output to a logic-high. a read of ll4 returns the voltage level at the upio4 pin at the time of the read regardless of how it is programmed. the power-on default is 0. msb lsb up4md3 up4md2 up4md1 up4md0 pup4 sv4 alh4 ll4 upio4_ctrl register (power-on state: 0000 1000) msb lsb up3md3 up3md2 up3md1 up3md0 pup3 sv3 alh3 ll3 upio3_ctrl register (power-on state: 0000 1000) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 49 upio2_ctrl register. this register configures theupio2 pin functionality. up2md<3:0>: upio2-mode selection bits. these bits configure the mode for the upio2 pin. see table 16 fora detailed description. the power-on default is 0 hex. pup2: pullup upio2 control bit. set pup2 = 1 to enable a weak pullup resistor on the upio2 pin and setpup2 = 0 to disable it. the pullup resistor is connected to either dv dd or cpout as programmed by the sv2 bit. the pullup is enabled only when upio2 is config-ured as an input. op en-drain behavior can be simulated at upio2 by setting the mode to gpo with ll2 = 0 andby changing the mode to gpi with pup2 = 0, allowing external high pullup. the power-on default is 1. sv2: supply-voltage upio2 selection bit. set sv2 = 0 to select dv dd as the supply voltage for the upio2 pin and set sv2 = 1 to select cpout as the supply volt-age. the selected supply voltage applies to all modes for the upio2 pin. the power-on default is 0. alh2: active logic-level assertion high upio2 bit. set alh2 = 0 to define the input or output assertion levelfor upio2 as low except when in gpi and gpo modes and set alh2 = 1 to define the input or output assertion level as high. for example, asserting alh2 defines the upio2 output signal as alarm, while deasserting alh2 defines it as alarm . similarly, asserting alh2 defines the upio2 input signal as wu, while deassert-ing alh2 defines it as wu . the power-on default is 0. ll2: logic-level upio2 bit. when upio2 is configured as gpo, ll2 = 0 sets the output to a logic-low and ll2= 1 sets the output to a logic-high. a read of ll2 returns the voltage level at the upio2 pin at the time of the read regardless of how it is programmed. the power-on default is 0. upio1_ctrl register. this register configures theupio1 pin functionality. up1md<3:0>: upio1-mode selection bits. these bits configure the mode for the upio1 pin. see table 16 fora detailed description. the power-on default is 0 hex. pup1: pullup upio1 control bit. set pup1 = 1 to enable a weak pullup resistor on the upio1 pin and setpup1 = 0 to disable it. the pullup resistor is connected to either dv dd or cpout as programmed by the sv1 bit. the pullup is enabled only when upio1 is config-ured as an input. op en-drain behavior can be simulated at upio1 by setting the mode to gpo with ll1 = 0 andby changing the mode to gpi with pup1 = 0, allowing external high pullup. the power-on default is 1. sv1: supply-voltage upio1 selection bit. set sv1 = 0 to select dv dd as the supply voltage for the upio1 pin and set sv1 = 1 to select cpout as the supply volt-age. the selected supply voltage applies to all modes for the upio1 pin. the power-on default is 0. alh1: active logic-level assertion high upio1 bit. set alh1 = 0 to define the input or output assertion levelfor upio1 as low except when in gpi and gpo modes and set alh1 = 1 to define the input or output assertion level as high. for example, asserting alh1 defines the upio1 output signal as alarm, while deasserting alh1 defines it as alarm . similarly, asserting alh1 defines the upio1 input signal as wu, while deassert-ing alh1 defines it as wu . the power-on default is 0. ll1: logic-level upio1 bit. when upio1 is configured as gpo, ll1 = 0 sets the output to a logic-low and ll1= 1 sets the output to a logic-high. a read of ll1 returns the voltage level at the upio1 pin at the time of the read regardless of how it is programmed. the power-on default is 0. msb lsb up2md3 up2md2 up2md1 up2md0 pup2 sv2 alh2 ll2 upio2_ctrl register (power-on state: 0000 1000) msb lsb up1md3 up1md2 up1md1 up1md0 pup1 sv1 alh1 ll1 upio1_ctrl register (power-on state: 0000 1000) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 50 _________________________________________________ _____________________________________ up4md<3:0>, up3md<3:0>, up2md<3:0>, up1md<3:0> mode description 0000 g p i general-purpose digital input. active edges detected by upr_ or upf_ statusregister bits. alh_ has no effect with this setting. 0001 g p o general-purpose digital output. logic level set by ll_ bit. alh_ has no effect withthis setting. 0010 swa or swa digital input. dac a buffer switch control. see the swa bit description in the sw_ctrl register section. 0011 reserved reserved. do not use these settings. 0100 spdt1 or spdt1 d i g i tal i np ut. s p d t1 sw i tch contr ol . s ee the s p d t1< 1:0> b i t d escr i p ti on i n the s w _c trl reg i ster secti on. 0101 spdt2 or spdt2 d i g i tal i np ut. s p d t2 sw i tch contr ol . s ee the s p d t2< 1:0> b i t d escr i p ti on i n the s w _c trl reg i ster secti on. 0110 sleep or sleep sleep-mode digital input. overrides power-control register and puts the part into sleep mode when asserted. when deasserted, power mode is determined by the shdn bit. 0111w u o r wu wake-up digital input. asserted edge clears shdn bit. 1000 1001 1010 reserved reserved. do not use these settings. 1011 pwm or pwm pwm digital output. signal defined by the pwm_ctrl register. pwm on (or high or ??; assertion level defined by the alh_ bit. when pwm is disabled (pwme = 0), the upio pin idles high (dv dd or cpout) if alh = 1, and low (dgnd) if alh = 0. 1100 shdn or shdn power-supply shutdown digital output. equivalent to shdn bit. power-on default ofgpi with pullup ensures initial power-supply turn-on when upio is connected to a power supply with a shdn input. 1101 al_day or al_day rtc alarm digital output. asserts for time-of-day alarm events; equivalent to ald in status register. 1110 reserved reserved. do not use these settings. 1111 drdy or drdy adc data-ready digital output. asserts when analog-to-digital conversion orcalibration completes. not masked by madd bit. table 16. upio mode configuration note: when multiple upio inputs are configured for the same input function, the inputs are or?d together. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 51 upio spi pass-through control register. these bits mapthe serial interface signals to the upio pins, allowing the das (max1359b) to drive other devices at cpout or dv dd voltage levels, depending on the sv_ bit setting found in the upio_ctrl register. individual bits are pro-vided to set only the desired upio inputs to the spi pass-through mode. this mode becomes active when cs is driven high to complete the write to this register, and remains active as long as cs stays high (i.e., multi- ple pass-through writes are possible). the spi pass-through mode is deactivated immediately when cs is pulled low for the next das (max1359b) write.the upio_ state (both before and after the spi pass- through mode) is set by the up_md<3:0> and ll_ bits. when a upio is configured for spi pass-through mode and the cs is high, upr_, upf_, and ll_ continue to detect upio_ edges, which can still generate interrupts.see figure 18 for an spi pass-through timing diagram. up4s: upio4 spi pass-through-mode enable bit. a logic 1 maps the inverted cs signal to the upio4 pin. therefore, upio4 is low (near dgnd) when spi pass-through mode is active, and is high (near dv dd or cpout) when the mode is inactive. a logic 0 disablesthe upio4 spi pass-through mode. the power-on default is 0. up3s: upio3 spi pass-through-mode enable bit. a logic 1 maps the sclk signal to upio3 (directly with noinversion), while a logic 0 disables the upio3 spi pass- through mode. the power-on default is 0. up2s: upio2 spi pass-through-mode enable bit. a logic 1 maps the din signal to upio2 (directly with noinversion), while a logic 0 disables the upio2 spi pass- through mode. the power-on default is 0. up1s: upio1 spi pass-through-mode enable bit. a logic 1 maps the upio1 input signal to dout (directlywith no inversion), while a logic 0 disables the upio1 spi pass-through mode. the power-on default is 0. cs write to das to enable spi mode write through das to upio device normal write to das sclk din d n d n-1 d n-2 d n-3 d 3 d 2 d 1 d 0 e n e n-1 e n-2 e n-3 x x x x e n e n-1 e n-2 e n-3 x x x x d 7 d 6 d 5 d 4 d 3 d 2 d 1 d 0 dout e 3 e 2 e 1 e 0 e 3 e 2 e 1 e 0 upio4 set by upio4_ctrl register set by upio4_ctrl register upio3 set by upio3_ctrl register set by upio3_ctrl register upio2 set by upio2_ctrl register set by upio2_ctrl register upio1 set by upio1_ctrl register set by upio1_ctrl register figure 18. spi pass-through timing diagram msb lsb up4s up3s up2s up1s x x x x upio_spi register (power-on state: 0000 xxxx) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 52 _________________________________________________ _____________________________________ the switch-control register controls the two spdtswitches (spdt1 and spdt2) and the daca output buffer spst switch (swa). control these switches by the serial bits in this register, by any of the upio pins that are enabled for that function, or by the pwm. swa: (max1359b) daca output buffer spst-switch a control bit. the swa bit, the upio inputs (if configured),and the pwm (if configured) control the state of the swa switch as shown in table 17. the upio_ states of 0 and 1 in table 17 correspond to respective deassert- ed and asserted logic states as defined by the alh_ bit of the upio_ctrl register. if a upio is not configured for this mode, its value applied to table 17 is 0. the pwm states of 0 and 1 in the table below correspond to the respective pwm off (or low) and on (or high) states defined by the swah and swal bits (see the pwm_ctrl register section). if the pwm is not config- ured for this mode, its value applied to the table belowis 0. the power-on default is 0. spdt1<1:0>: single-pole double-throw switch 1 con- trol bits. the spdt1<1:0> bits, the upio pins (if config-ured), and the pwm (if configured) control the state of the switch as shown in table 18. the upio_ states of 0 and 1 in table18 correspond to respective deasserted and asserted logic states as defined by the alh_ bit of the upio_ctrl register. if a upio is not configured for this mode, its value applied to table 18 is 0. the pwm states of 0 and 1 in table 18 below correspond to the respective pwm off (low) and on (high) states defined by the spd1 bit in the pwm_ctrl register. if the pwm is not configured for this mode, its value applied to table 18 is 0. the power-on default is 00. msb lsb swa 0 spdt11 spdt10 spdt21 spdt20 x x sw_ctrl register (power-on state: 0000 00xx) swa bit* upio_* pwm* swa switch state 0 0 0 switch open x x 1 switch closed x 1 x switch closed 1 x x switch closed table 17. swa states x = don? care. * switch swa control is effectively an or of the swa bit, upio pins, and pwm. spdt1<1:0> upio_* pwm* spdt1 switch state 0 0 0 0 sno1 open, snc1 open 0 x x 1 sno1 closed, snc1 closed 0 x 1 x sno1 closed, snc1 closed 0 1 x x sno1 closed, snc1 closed 1 0 0 0 snc1 closed, sno1 open 1 x x 1 snc1 open, sno1 closed 1 x 1 x snc1 open, sno1 closed 1 1 x x snc1 open, sno1 closed table 18. spdt switch 1 states x = don? care. * switch spdt1 control is effectively an or of the spdt10 bit, the upio pins, and the pwm output. the spdt11 bit determines if the switches open and close together or if they toggle. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 53 spdt2<1:0>: single-pole double-throw switch 2 control bits. the spdt2<1:0> bits, the upio pins (if config-ured), and the pwm (if configured) control the state of the switch as shown in table 19. the upio_ states of 0 and 1 in the table correspond to respective deasserted and asserted logic states as defined by the alh_ bit in the upio_ctrl register. if a upio is not configured for this mode, its value applied to table 19 is 0. the pwm states of 0 and 1 in table 19 correspond to the respec- tive pwm off (low) and on (high) states defined by the spd2 bit in the pwm_ctrl register. if the pwm is not configured for this mode, its value applied to table 19 is 0. the power-on default is 00. spdt2<1:0> upio_* pwm* spdt2 switch state 0 0 0 0 sno2 open, snc2 open 0 x x 1 sno2 closed, snc2 closed 0 x 1 x sno2 closed, snc2 closed 0 1 x x sno2 closed, snc2 closed 1 0 0 0 snc2 closed, sno2 open 1 x x 1 snc2 open, sno2 closed 1 x 1 x snc2 open, sno2 closed 1 1 x x snc2 open, sno2 closed table 19. spdt switch 2 states x = don? care. * switch spdt2 control is effectively an or of the spdt20 bit, the upio pins, and the pwm output. the spdt21 bit determines if the switches open and close together or if they toggle. the temperature-sensor control register controls theinternal and external temperature measurement. imux<1:0>: internal current-source mux bits. selects the pin to be driven by the internal current sources asshown in table 20. the power-on default is 00. ival<1:0>: internal current-source value bits. selects the value of internal current source as shown in table21. the power-on default is 00. this register is the internal temperature sensor calibra-tion register. tgain<7:0>: factory-preset temperature gain correction coefficient bits. this is the linear scaling factor used toderive absolute temperature values from temperature val- ues measured with the internal temperature sensor (t ac- tual = t meas x t gain + t offs ). this method does not correct for delta v be absolute voltage measurement errors, and assumes the measurement is taken with a ref-erence voltage that is either exactly 1.250v, or an exact value known by the user. the errors being corrected by this factor are variables in the internal temperature-sens- ing diode. this factor is programmed to typical values. the power-on default varies. toffs<5:0>: factory-preset temperature offset correc- tion coefficient bits. this is the linear offset factor usedto derive absolute temperature values from temperature values measured with the internal temperature sensor (t actual = t meas x t gain + t offs ). this method does not correct for delta v be absolute voltage mea- surement errors, and assumes the measurement wastaken with a reference voltage that is either exactly 1.250v, or an exact value known by the user. the errors being corrected by this factor are variables in the inter- nal temperature-sensing diode. this factor is based on characterization data. the power-on default varies. msb lsb imux1 imux0 ival1 ival0 x x x x temp_ctrl register (power-on state: 0000 xxxx) current source imux1 imux0 disabled 0 0 internal temperature sensor 0 1 ain1 1 0 ain2 1 1 table 20. selecting internal current source current typical current (?) ival1 ival0 i 1 40 0 i 2 60 0 1 i 3 64 1 0 i 4 120 1 1 table 21. setting the current level msb tgain7 tgain6 tgain5 tgain4 tgain3 tgain2 tgain1 tgain0 lsb toffs5 toffs4 toffs3 toffs2 toffs1 toffs0 x x temp_cal register (power-on state: varies by factory calibration) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 54 _________________________________________________ _____________________________________ the imsk register determines which bits of the statusregister generate an interrupt on int. the bits in this register do not mask output signals routed to upio since the output signals are masked by disabling that upio function. mldvd: ldvd status bit mask. set mldvd = 0 to enable the ldvd status bit interrupt to int and setmldvd = 1 to mask the ldvd status bit interrupt. the power-on default value is 1. mlcpd: lcp status bit mask. set mlcp = 0 to enable the lcp status bit interrupt to int and set mlcp = 1 tomask the lcp status bit interrupt. the power-on default value is 1. mado: ado status bit mask. set mado = 0 to enable the ado status bit interrupt to int and set mado = 1 tomask the ado status bit interrupt. the power-on default value is 1. msdc: sdc status bit mask. set msdc = 0 to enable the sdc status bit interrupt to int and set msdc = 1 tomask the sdc status bit interrupt. the power-on default value is 1. mcrdy: crd status bit mask. set mcrdy = 0 to enable the crdy status bit interrupt to int and set mcrdy = 1 to mask the crdy status bit interrupt. thepower-on default value is 0. madd: add status bit mask. set madd = 0 to enable the add status bit interrupt to int and set madd = 1 tomask the add status bit interrupt. the power-on default value is 1. mald: ald status bit mask. set mald = 0 to enable the ald status bit interrupt to int and set mald = 1 tomask the ald status bit interrupt. the power-on default value is 1. mupr<4:1>: upr<4:1> status bits mask. set mupr_ = 0 to enable the upr_ status bit interrupt to int and setmupr_ = 1 to mask the upr_ status bit interrupt. (_ = 1, 2, 3, or 4 and corresponds to the upio1, upio2, upio3, or upio4 pins, respectively.) the power-on default value is f hex. mupf<4:1>: upf<4:1> status bits mask. set mupf_ = 0 to enable the upf_ status bit interrupt to int and setmupf_ = 1 to mask the upf_ status bit interrupt. (_ = 1, 2, 3, or 4 and corresponds to the upio1, upio2, upio3, or upio4 pins, respectively.) the power-on default value is f hex. this register is the power-supply and voltage monitorscontrol register. ldoe: low-dropout linear-regulator enable bit. set ldoe = 1 to enable the low-dropout linear regulator toprovide the internal source voltage for the charge pump. set ldoe = 0 to disable the ldo, allowing an external drive to the charge pump input through reg. the power-on default value is 0. cpe: charge-pump enable bit. set cpe = 1 to enable the charge-pump doubler and set cpe = 0 to disable thecharge-pump doubler. the power-on default value is 0. lsde: dv dd low-supply voltage-detector power- enable bit. set lsde = 1 to enable the +1.8v (dv dd ) low-supply-voltage detector and set lsde = 0 to dis- able the dv dd low-supply-voltage detector. the power- on default value is 1. cpde: cpout low-supply voltage-detector power- enable bit. set cpde = 1 to enable the +2.7v cpoutlow-supply voltage-detector comparator and set cpde = 0 to disable the cpout low-supply voltage-detector comparator. the power-on default value is 0. hyse: dv dd low-supply voltage-detector hysteresis- enable bit. set hyse = 1 to set the hysteresis for the+1.8v (dv dd ) low-supply-voltage detector to +200mv and set hyse = 0 to set the hysteresis to +20mv. on initialpower-up, the hysteresis is +20mv and can be pro- grammed to 200mv once reset goes high. once pro- grammed to +200mv, the dv dd falling threshold is +1.8v msb mldvd mlcpd mado msdc mcrdy madd mald x lsb mupr4 mupr3 mupr2 mupr1 mupf4 mupf3 mupf2 mupf1 imsk register (power-on state: 1111 011x 1111 1111) msb lsb ldoe cpe lsde cpde hyse rste x x ps_vmons register (power-on state: 0010 01xx) downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 55 nominally and the rising threshold is +2.0v nominally. thehysteresis helps eliminate chatter when running directly off unregulated batteries. if dv dd falls below +1.3v (typ), the power-on reset circuitry is enabled and the hyse bit isdeasserted setting the hysteresis back to +20mv. the power-on default is 0. rste: reset output enable bit. set rste = 1 to enable reset to be controlled by the +1.8v dv dd low- supply-voltage detector and set rste = 0 to disablethis control. the power-on default is 1. msb ldvd lcpd adou sdc crdy add ald x lsb upr4 upr3 upr2 upr1 upf4 upf3 upf2 upf1 status register (power-on state: 0000 000x 0000 0000) the status register contains the status bits of events invarious system blocks. any status bits not masked in the imsk register cause an interrupt on int. some of the status bit setting events (gpi, wakeup, alarm, drdy) can be directed to upio_ to provide multiple ? inter- rupt inputs. there are no specific mask bits for the upio interrupt signals since the bits are effectively masked by selecting a different function for upio. the status bits always record the triggering event(s), even for masked bits, which do not generate an interrupt on int. it is pos- sible to set multiple status bits during a single int interrupt event. clear all status bits except for add and adou by reading the status register. during a sta- tus register read, int deasserts when the first status data bit (ldvd) reads out (9th rising sclk) and remains deasserted until shortly after the last status data bit (~15ns). at this point, int reasserts if any status bit is set during the status register read. if the status register is partially read (i.e., the read is aborted midway), none of the status bits are cleared. new events occurring dur- ing a status register read, or events that persist after reading the status bits result in another interrupt immediately after the status register read finishes. this is a read-only register. ldvd: low dv dd voltage-detector status bit. ldvd = 1 indicates dv dd is below the +1.8v threshold, otherwise ldvd = 0. ldvd clears during the status registerread as long as the condition does not persist. otherwise, the ldvd bit reasserts immediately. if the dv dd low voltage detector is disabled, ldvd = 0. the power-on default is 0. lcpd: low cpout voltage-detector status bit. lcpd = 1 indicates cpout is below the +2.7v threshold, other-wise lcpd = 0. lcpd clears during the status regis- ter read as long as the condition does not persist. otherwise the lcpd bit reasserts immediately. lcpd = 0 when the cpout low voltage detector is disabled. the power-on default is 0. adou: adc overflow/underflow status bit. adou = 1 indicates an adc underflow or overflow condition in thecurrent adc result. new conversions that are valid clear the adou bit. adou = 0 when the adc data is valid or the adc is disabled (adce = 0). an underflow condition occurs when the adc data is theoretically less than 0000 hex in unipolar mode and less than 8000 hex in bipolar mode. an overflow condition occurs when the adc data is theoretically greater than ffff hex in unipolar mode and greater than 7fff hex in bipolar mode. use this bit to determine the validity of an adc result at the maximum or minimum code values (i.e., 0000 hex or ffff hex for unipolar mode and 8000 hex and 7fff hex for bipolar mode). the power-on default is 0. reading the status register does not clear the adou bit. sdc: signal-detect comparator status bit. when sdc = 1, the positive input to the signal-detect comparatorexceeds the negative input plus the programmed thresh- old voltage. the sdc bit clears during the status regis- ter read unless the condition remains true. the sdc bit also deasserts when the signal-detect comparator pow- ers down (sdce = 0). the power-on default is 0. crdy: high-frequency-clock ready status bit. crdy = 1 indicates a locked high-frequency clock to the 32khzreference frequency by the fll. the crdy bit clears during the status register read. this bit only asserts after power-up or after enabling the fll using the flle bit. the power-on default is 0. add: adc-done status bit. add = 1 indicates a com- pleted adc conversion or calibration. clear the add bitby reading the appropriate adc data, offset, or gain-cali- bration registers. the adc status bit also clears when a new adc result updates to the data or calibration regis- ters (i.e., it follows the assertion level of the upio = drdy signal). reading the status register does not clear this bit. this bit is equivalent to the drdy signal available through upio_. the power-on default is 0. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 56 _________________________________________________ _____________________________________ ald: alarm (day) status bit. ald = 1 when the value programmed in asec<19:0> in the al_day registermatches sec<19:0> in the rtc register. clear the ald bit by reading the status register or by disabling the day alarm (ade = 0). the power-on default is 0. upr<4:1>: user-programmable i/o rising-edge status bits. upr_ = 1 indicates a rising edge on the respec-tive upio_ pin has occurred. clear upr_ by reading the status register. rising edges are detected inde- pendent of upio_ configuration, providing the ability to capture and record rising input (e.g., wu) or output (e.g., pwm) edge events on the upio_. set the appro- priate mask to determine if the edge will generate an interrupt on int. if the upio_ is configured as an out- put, int provides confirmation that an intended rising edge output occurred and has reached the desired dv dd or cpout level (i.e., was not loaded down exter- nally). the power-on default is 0. upf<4:1>: user-programmable i/o falling-edge status bit. upf_= 1 indicates a falling edge on the respectiveupio_ has occurred. clear upf_ by reading the status register. falling edges are detected indepen- dent of upio_ configuration, providing the ability to cap- ture and record falling input (e.g., wu) or output (e.g., pwm) edge events on the upio_. set the appropriate mask to determine if that edge should generate an inter- rupt on the int pin. if the upio is configured as an out- put, the int provides confirmation that an intended falling edge output occurred at the pin and it reached the desired dgnd level. the power-on default is 0. applications information analog filtering the internal digital filter does not provide rejectionclose to the harmonics of the modulator sample fre- quency. however, due to high oversampling ratios in the max1359b, these bands typically occupy a small fraction of the spectrum and most broadband noise is filtered. therefore, the analog filtering requirements in front of the max1359b are considerably reduced com- pared to a conventional converter with no on-chip filter- ing. in addition, because the device? common-mode rejection (60db) extends out to several khz, the com- mon-mode noise susceptibility in this frequency range is substantially reduced. depending on the application, provide filtering prior to the max1359b to eliminate unwanted frequencies the digital filter does not reject. providing additional filtering in some applications ensures that differential noise sig-nals outside the frequency band of interest do not satu- rate the analog modulator. when placing passive components in front of the max1359b, ensure a low enough source impedance to prevent introducing gain errors to the system. this config- uration significantly limits the amount of passive anti-alias- ing filtering that can be applied in front of the max1359b. see table 3 for acceptable source impedances. power-on reset or power-up after a power-on reset, the dv dd voltage supervisor is enabled and all upios are configured as inputs withpullups enabled. the internal oscillators are enabled and are output at clk and clk32k once the dv dd voltage supervisor is cleared and the subsequent timeout periodhas expired. all interrupts are masked except crdy. figure 19 illustrates the timing of various signals during initial power-up, sleep mode, and wake-up events. the adc, charge pump, internal reference, op amp(s), dac(s), and switches are disabled after power-up. power modes two power modes are available for the max1359b;sleep and normal mode. in sleep mode, all functional blocks are powered down except the serial interface, data registers, internal bandgap, wake-up circuitry (if enabled), dv dd voltage supervisor (if enabled), and the 32khz oscillator (if enabled), which remain active.see table 15 for details of the sleep-mode and normal- mode power states of the various internal blocks. each analog block can be shut down individually through its respective control register with the excep- tion of the bandgap reference. sleep mode sleep mode is entered one of three ways: writing to the sleep register address. the result is the shdn bit is set to 1. asserting the sleep or sleep function on a upio (sleep takes precedence over software writes orwake-up events). the shdn bit is unaffected. asserting the shdn bit by writing slp = 1 in the sleep_cfg register. entering sleep mode is an or function of the upio orshdn bit. before entering sleep mode, configure the normal mode conditions. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 57 internal low dv dd detector output disabled, but pulled low output enabled sclk, din cs dout internal drdy upio( pwm ) tied to power supply shdn pin int upio( shdn ) upio( wu ) (int. pullup) ck32k (32khz) sck32e = 0 buffer disabled ck32e = 1 ck32e = 1 xin, xout (32khz) sosce = 1 osce = 1 osce = 1 por dv dd 1.8v av dd 1.8v reset (open-drain) internal external internal crdy hfce = 1, flle = 1 clk lo hi lo hi lo hi lo hi lo hi lo hi lo hi lo hi lo hi lo hi lo hi lo hi 0v 1 2 0v 1 2 lo hi lo hi lo hi sleepwrite tri-stated spwme = 1 pwme = 0 pwme = 0 power supply off power supply off t dpu t dfi t dfi internal t wu t dfon t dfon t dfof t dpd internal if flle = 0, crdy will stay low, dfon = 0 ) initial power, wake-up, and sleep xtal b/w 32kin and 32kout pin figure 19. initial power-up, sleep mode, and wake-up timing diagram with av dd > 1.8v downloaded from: http:///
exit sleep mode and enter normal mode by one of thefollowing methods: with the shdn bit = 0, deassert the sleep or sleep function on upio, only if sleep or sleep function is used for entering sleep mode. with the sleep or sleep function deasserted on upio, clear the shdn bit by writing to the normal-mode register address control byte. with the sleep or sleep function deasserted, assert wu or wu (wake-up) function on upio. with the sleep or sleep function deasserted, the day alarm triggers. wake-up a wake-up event, such as an assertion of a upio con-figured as wu or a time-of-day alarm causes the max1359b to exit sleep mode, if in sleep mode. a wake-up event in normal mode results only in a wake- up event being recorded in the status register. reset the reset output pulls low for any one of the following cases: power-on reset, dv dd monitor trips and rste = 0, watchdog timer expires, crystal oscillator is attached,and 32khz clock not ready. the reset output can be turned off through the rste bit in the ps_vmons register, causing dv dd low sup- ply voltage events to issue an interrupt or poll throughthe ldvd status bit. this allows brownout detection ?s that operate with dv dd < 1.8v. driving upio outputs to av dd levels upio outputs can be driven to av dd levels in systems with separate av dd and dv dd supplies. disable the charge-pump doubler by setting cpe = 0 in theps_vmons register, and connect the system? analog supply to av dd and cpout. setting upio outputs to drive to cpout results in av dd -referenced logic levels. supply voltage measurement the av dd supply voltage can be measured with the adc by reversing the normal input and reference sig-nals. the ref voltage is applied to one multiplexer input and agnd is selected in the other. the av dd sig- nal is then switched in as the adc reference voltageand a conversion is performed. the av dd value can then be calculated directly as: v avdd = (v ref x gain x 65536) / n where v ref is the reference voltage for the adc, gain is the pga gain before the adc, and n is the adcresult. note the av dd voltage must be greater than the gained-up ref voltage (av dd > v ref x gain). this measurement must be done in unipolar mode. power supplies av dd and dv dd provide power to the max1359b. the av dd powers up the analog section, while the dv dd powers up the digital section. the power supply for bothav dd and dv dd ranges from +1.8v to +3.6v. both av dd and dv dd must be greater than +1.8v for device operation. av dd and dv dd can connect to the same power supply. bypass av dd to agnd with a 10? elec- trolytic capacitor in parallel with a 0.1? ceramic capaci-tor and bypass dv dd to dgnd with a 10? electrolytic capacitor in parallel with a 0.1? ceramic capacitor. forimproved performance, place the bypass capacitors as close to the device as possible. adc transfer functions figures 20 and 21 provide the adc transfer functionsfor unipolar and bipolar mode. the digital output code format is binary for unipolar mode and two? comple- ment for bipolar mode. calculate 1 lsb using the fol- lowing equations: 1 lsb (unipolar mode) = v ref / (gain x 65,536) 1 lsb (bipolar mode) = ?v ref / (gain x 65,536) where v ref equals the reference voltage at ref and gain equals the pga gain.in unipolar mode, the output code ranges from 0 to 65,535 for inputs from zero to full-scale. in bipolar mode, the output code ranges from -32,768 to +32,767 for inputs from negative full-scale to positive full-scale. max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 58 _________________________________________________ _____________________________________ 0000 0000 0000 0000 0000 0000 0000 0001 0000 0000 0000 0010 65,535 65,533 input voltage (lsb) binary output code 1111 1111 1111 1101 1111 1111 1111 1110 1111 1111 1111 1111 1 lsb = v ref (gain x 65,536) 0 2 v ref /gain v ref /gain 13 1111 1111 1111 1100 0000 0000 0000 0011 full-scale transition figure 20. adc unipolar transfer function downloaded from: http:///
max1359b dac unipolar output for a unipolar output, the output voltages and the refer-ence have the same polarity. figure 22 shows the max1359b? unipolar output circuit, which is also the typical operating circuit for the dac. table 22 lists some unipolar input codes and their corresponding output voltages. for larger output swing, see figure 23. this circuit shows the output amplifiers configured with a closed- loop gain of +2v/v to provide 0 to 2.5v full-scale range with the 1.25v reference. dac bipolar output the max1359b dac outputs can be configured for bipo-lar operation using the application circuit in figure 24: where n is the decimal value of the dac? binary input code. table 23 shows digital codes (offset binary) and corre-sponding output voltages for figure 24 assuming r1 = r2. vv n out ref = ? ? ? ? ? ? ? ? ? ? ? ? 2 1024 1 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 59 max1359b dac a outa ref fba figure 22. dac unipolar output circuit 0+1 -1 1000 0000 0000 0000 1000 0000 0000 0001 1000 0000 0000 0010 +32,767 +32,765 input voltage (lsb) binary output code 0111 1111 1111 1101 0111 1111 1111 1110 0111 1111 1111 1111 0000 0000 0000 0000 0000 0000 0000 0001 1111 1111 1111 1111 1 lsb = v ref (gain x 65,536) x 2 -32,768 -32,766 v ref /gain v ref /gain v ref /gain v ref /gain figure 21. adc bipolar transfer function max1359b dac a outa v ref = 1.25v ref fba 10k ? 10k ? figure 23. dac unipolar rail-to-rail output circuit dac contents msb lsb analog output 1111 1111 11 +v ref (1023/1024) 1000 0000 01 +v ref (513/1024) 1000 0000 00 +v ref (512/1024) = +v ref / 2 0111 1111 11 +v ref (511/1024) 0000 0000 01 +v ref (1/1024) 0000 0000 00 0 table 22. unipolar code dac contents msb lsb analog output 1111 1111 11 +v ref (511/512) 1000 0000 01 +v ref (1/512) 1000 0000 00 0 0111 1111 11 -v ref (1/512) 0000 0000 01 -v ref (511/512) 0000 0000 00 -v ref (512/512) = -v ref table 23. bipolar code downloaded from: http:///
optical reflectometry application with dual led and single photodiode figure 25 illustrates the max1359b in a complete opticalreflectometry application with two transmitting leds and one receiving photodiode. the leds transmit light at a specific wavelength onto the sample strip and the photo- diode receives the reflections from the strip. set the dac to provide appropriate bias currents for the leds. always keep the photodiodes reverse-biased or zero-biased. spdt1 and spdt2 switch between the two leds. electrochemical sensor operation the max1359b interfaces with electrochemical sen-sors. the 10-bit dac with the force-sense buffer has the flexibility to connect to many different types of sensors. temperature measurement with two remote sensors use two diode-connected 2n3904 transistors for exter-nal temperature sensing in figure 26. select ain1 and ain2 through the positive and negative mux, respec- tively. for internal temperature sensor measurements, set muxp<3:0> to 0111, and set muxn<3:0> to 0000. the analog input signals feed through a pga to the adc for conversion. programmable-gain instrumentation amplifier use two op amps and two spdt switches to implementa programmable-gain instrumentation amplifier as shown in figure 27. pwm applications the max1359b integrated pwm is available for lcdbias control, sensor-bias voltage trimming, buzzer drive, and duty-cycled sleep-mode power-control schemes. figure 28 shows the max1359b performing lcd bias control. figures 30 and 31 show the pwm cir- cuitry being used in a single-ended and differential piezoelectric buzzer-driving application. adc calibration internal to the max1359b, the adc is 24 bits and isalways in bipolar mode. the offset cal and gain cal data are also 24 bits. the conversion to unipolar and the gain are performed digitally. the default values for the offset cal and gain cal registers in the max1359b are 00 0000h and 80 0000h, respectively. the calibration works as follows: adc = (raw - offset) x gain x pga where adc is the conversion result in the data regis-ter, raw is the output of the decimation filter internal to the max1359b, offset is the value stored in the off- set cal register, gain is the value stored in the gain cal register, and pga is the selected pga gain found in the adc register as gain<1:0>. in unipolar mode, all negative values return a zero result and an additional gain of 2 is added. for self-calibration, the offset value is the raw result when the inputs are shorted internally and the gain value is 1 / (raw - offset) with the reference connected to the input. this is done automatically when these modes are selected. the self offset and gain calibration corrects for errors internal to the adc and the results are stored and used automatically in the offset cal and gain cal registers. for best results, use the adc in the same configuration as the calibration. this pertains to conver- sion rate only because the pga gain and unipolar/bipo- lar modes are performed digitally. for system calibration, the offset and gain values cor- rect for errors in the whole signal path including the internal adc and any external circuits in the signal path. for the system calibration, a user-provided zero- input condition is required for the offset calibration and a user-provided full-scale input is required for the gain calibration. these values are automatically written to the offset cal and gain cal registers. the order of the calibrations should be offset followed by gain. the offset correction value is in two? complement. the default value is 000000h, 00...00b, or 0 decimal. the gain correction value is an unsigned binary number with 23 bits to the right of the decimal point. the largest number is therefore 1.1111...1b = 2 - 2 -23 and the small- est is 0.000...0b = 0, although it does not make sense touse a number smaller than 0.1000...0b = 0.5. the default value is 800000h, 1.000...0b or 1 decimal. changing the offset or gain calibration values does not affect the value in the data register until a new conver- sion has completed. this applies to all the mode bits for pga gain, unipolar/bipolar, etc. max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 60 _________________________________________________ _____________________________________ r 2 r 2 = r 1 r 1 max1359b dac_ out_ v out +3.3v -3.3v fb_ v ref = 1.25v v ref figure 24. dac bipolar output circuit downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 61 c down up mem v ss inputinput input upio2 upio1 upio3 upio4 max1359b din dout sclkcs reset int clk clk32k av dd dv dd test strip v ss agnddgnd 32kin 32kout 32.768khz linear reg dv dd charge- pump doubler v ss reg cf+cf- cpout v ss v bat 2 aaa or1 lithium coin cell v ss v ss v dd cs2 reset input x2in 32kin eeprom v ss v bat gnd v cc cs sisck so serial-port interface v ss cs1 sck miso mosi v ss v cp v ss txd rxd v cp high-frequency micro clock 32khz micro clock lcd module bdin bdoutbsclk bcs2 v ss v cp in2- in2+ out2 in1- in1+ out1 v ss adc pwm daca ref bg led v cp v cp led ambient light led sources snc1 scm1 sno1 fba v ss swa outa ain1 ain2 scm2 snc2 sno2 v ss 1nf v ss cs2 figure 25. optical reflectometry application with dual led and single photodiode downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 62 _________________________________________________ _____________________________________ a v = 1, 2, 4, 8 a v = 1, 1.638, 2 max1359b pga mux 2n3904 16-bit adc c ref ref ref mux temp sensor ain1 agnd ain2 agnd 2n3904 1.25v ref figure 26. temperature measurement with two remote sensors max1359b r 3 r 2 r 2 r 3 r 1 r 1 in1+in1- scm1 v out scm2 out1 sno1snc1 sno2 snc2 v in+ v in- out2 in2+in2- figure 27. programmable-gain instrumentation amplifier downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 63 max1359b (1.8vto 2.6v) 0.01 f c mux sv_ alh_ upio_ lcd drivers seg lcd com n m cpout 200k ? 100k ? 100k ? 100k ? 100k ? pwm dv dd cpout en_ figure 28. lcd contrast-adjustment application shdn pwm alh_ upio_ sv_ dv dd cpout mux max1359b v in vout power supply av dd v dd c 100 f <10 a v dd psctl v batt dv dd on-time <100ms typ 10s period typ +3.3v v dd +2.3v psctl en_ 10m ? figure 29. power-supply sleep-mode duty-cycle control downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 64 _________________________________________________ _____________________________________ pwm alh_ upio_ sv_ dv dd cpout mux 1k ? 0v cpout(+3.2v) 1 to 8khz typ ~10,000pf max1359b figure 30. single-ended piezoelectric buzzer drive max1359b mux sv_ alh_ upio_ 1k ? pwm dv dd cpout mux sv_ alh_ upio_ 1k ? dv dd cpout 0v0v cpout(+3.2v) cpout + 6.4v diff - -cpout cpout(~+3.2v) 1 to 8khz typ1 to 8khz typ ~10,000pf figure 31. differential piezoelectric buzzer drive downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor ___________________________________________________ ___________________________________ 65 grounding and layout for best performance, use pc boards with separateanalog and digital ground planes. design the pc board so that the analog and digital sec- tions are separated and confined to different areas of the board. join the digital and analog ground planes at one point. if the das (max1359b) is the only device requiring an agnd-to-dgnd connection, connect planes to the agnd pin of the das. in systems where multiple devices require agnd-to-dgnd connections, the connection should still be made at only one point. make the star ground as close to the max1359b as possible. avoid running digital lines under the device because these may couple noise onto the device. run the ana- log ground plane under the max1359b to minimize coupling of digital noise. make the power-supply lines to the max1359b as wide as possible to provide low- impedance paths and reduce the effects of glitches on the power-supply line. shield fast-switching signals such as clocks with digital ground to avoid radiating noise to other sections of the board. avoid running clock signals near the analog inputs. avoid crossover of digital and analog signals. good decoupling is important when using high-resolu- tion adcs. decouple all analog supplies with 10? capacitors in parallel with 0.1? hf ceramic capacitors to agnd. place these components as close to the device as possible to achieve the best decoupling. crystal layout follow basic layout guidelines when placing a crystalon a pc board with a das to avoid coupled noise. 1) place the crystal as close as possible to 32kin and 32kout. keeping the trace lengths between thecrystal and inputs as short as possible reduces the probability of noise coupling by reducing the length of the ?ntennae? keep the 32kin and 32kout lines close to each other to minimize the loop area of the clock lines. keeping the trace lengths short also decreases the amount of stray capacitance. 2) keep the crystal solder pads and trace width to 32kin and 32kout as small as possible. the larg-er these bond pads and traces are, the more likely it is that noise will couple from adjacent signals. 3) place a guard ring (connect to ground) around the crystal to isolate the crystal from noise coupledfrom adjacent signals. 4) ensure that no signals on other pc board layers run directly below the crystal or below the traces to32kin and 32kout. the more the crystal is isolat- ed from other signals on the board, the less likely it is that noise will be coupled into the crystal. maintain a minimum distance of 5mm between any digital signal and any trace connected to 32kin or 32kout. 5) place a local ground plane on the pc board layer immediately below the crystal guard ring. thishelps to isolate the crystal from noise coupling from signals on other pc board layers. note: the ground plane must be in the vicinity of the crystal only and not on the entire board. parameter definitions inl integral nonlinearity (inl) is the deviation of the valueson an actual transfer function from a straight line. this straight line is either a best-straight-line fit or a line drawn between the endpoints of the transfer function, once offset and gain errors have been nulled. inl for the max1359b is measured using the endpoint method. dnl differential nonlinearity (dnl) is the difference betweenan actual step width and the ideal value of 1 lsb. a dnl error specification of greater than -1 lsb guarantees no missing codes and a monotonic transfer function. gain error gain error is the amount of deviation between the mea-sured full-scale transition point and the ideal full-scale transition point. common-mode rejection common-mode rejection (cmr) is the ability of adevice to reject a signal that is common to both input terminals. the common-mode signal can be either an ac or a dc signal or a combination of the two. cmr is often expressed in decibels. power-supply rejection ratio (psrr) power-supply rejection ratio (psrr) is the ratio of theinput supply change (in volts) to the change in the converter output (in volts). it is typically measured in decibels. downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor 66 _________________________________________________ _____________________________________ chip information process: bicmos package information for the latest package outline information and land patterns, goto www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only. package draw-ings may show a different suffix character, but the drawing per- tains to the package regardless of rohs status. package type package code outline no. land pattern no. 40 tqfn-ep t4066+5 21-0141 90-0055 downloaded from: http:///
max1359b 16-bit, data-acquisition system with adc, dac, upios, rtc, voltage monitors, and temp sensor maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 67 2010 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 2 8/10 changed all instances of max1358/max1359/max1360 to max1359b,added soldering temperature information, updated timing characteristics section, and updated package information section 1?3 downloaded from: http:///

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