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1 ltc139 2 micropower temperature, power supply and differential voltage monitor 1 2 3 4 8 7 6 5 v cc ? in +v in gnd d in d out clk cs ltc1392 ltc1392 ?ta01 5v + r sense i load 1 m f mpu (e.g., 68hc11) p1.4 p1.3 p1.2 temperature ( c) ?0 temperature error ( c) 5 4 3 2 1 0 ? ? ? ? ? 0 40 60 ltc1392 ?ta02 20 20 80 100 ltc1392c guaranteed limit ltc1392i guaranteed limit typical d u escriptio s f ea t u re n complete ambient temperature sensor onboard n system power supply monitor n 10-bit resolution rail-to-rail common-mode differential voltage input n available in 8-pin so and pdip n 0.2 m a supply current when idle n 700 m a supply current when sampling at maximum rate n single supply voltage: 4.5v to 6v n 3-wire half-duplex serial i/o n communicates with most mpu serial ports and all mpu parallel i/o ports the ltc ? 1392 is a micropower data acquisition system designed to measure temperature, on-chip supply voltage and a differential voltage. the differential inputs feature rail-to-rail common mode input voltage range. the ltc1392 contains a temperature sensor, a 10-bit a/d converter with sample-and-hold, a high accuracy bandgap reference and a 3-wire half-duplex serial interface. the ltc1392 can be programmed to measure ambient temperature, power supply voltage and an external volt- age at the differential input pins, that can also be used for current measurement using an external sense resistor. when measuring temperature, the output code of the a/d converter is linearly proportional to the temperature in c. production trimming achieves 2 c initial accuracy at room temperature and 4 c over the full C 40 c to 85 c temperature range. the on-chip serial port allows efficient data transfer to a wide range of mpus over three or four wires. this, coupled with low power consumption, makes remote location sensing possible and facilitates transmitting data through isolation barriers. u s a o pp l ic at i n temperature measurement n power supply measurement n current measurement n remote data acquisition n environment monitoring , ltc and lt are registered trademarks of linear technology corporation. u a o pp l ic at i ty p i ca l complete temperature, supply voltage and supply current monitor output temperature error
2 ltc139 2 a u g w a w u w a r b s o lu t exi t i s wu u package / o rder i for atio (note 1) supply voltage (v cc ) ................................................ 7v input voltage ................................. C 0.3v to v cc + 0.3v output voltage ............................... C 0.3v to v cc + 0.3v operating temperature range ltc1392c............................................... 0 c to 70 c ltc1392i ........................................... C 40 c to 85 c junction temperature.......................................... 125 c storage temperature range ................ C 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c order part number s8 part marking 1392 1392i consult factory for military grade parts. (note 2, 3) e lectr ic al c c hara terist ics ltc1392cn8 ltc1392cs8 ltc1392in8 ltc1392is8 t jmax = 125 c, q ja = 100 c/ w (n8) t jmax = 125 c, q ja = 130 c/ w (s8) 1 2 3 4 8 7 6 5 top view d in d out clk cs v cc ? in +v in gnd s8 package 8-lead plastic so n8 package 8-lead pdip parameter conditions min typ max units power supply to digital conversion resolution v cc = 4.5v to 6v 10 bit total absolute error v cc = 4.5v to 6v l 8 lsb differential voltage to digital conversion (full-scale input = 1v) resolution 10 bit integral linearity error (note 5) l 0.5 1 lsb differential linearity error l 0.5 1 lsb offset error l 4 lsb full-scale error l 15 lsb differential voltage to digital conversion (full-scale input = 0.5v) resolution 10 bit integral linearity error (note 5) l 0.5 2 lsb differential linearity error l 0.5 1 lsb offset error l 8 lsb full-scale error l 25 lsb temperature to digital conversion accuracy t a = 25 c (note 7) 2 c t a = t max or t min (note 7) l 4 c nonlinearity t min t a t max (note 4) 1 c
3 ltc139 2 symbol parameter conditions min typ max units i on leakage on-channel leakage current (note 6) l 1 m a i off leakage off-channel leakage current (note 6) l 1 m a v ih high level input voltage v cc = 5.25v l 2v v il low level input voltage v cc = 4.75v l 0.8 v i ih high level input current v in = v cc l 5 m a i il low level input current v in = 0v l C5 m a v oh high level output voltage v cc = 4.75v, i out = 10 m a l 4.5 4.74 v v cc = 4.75v, i out = 360 m a 2.4 4.72 v v ol low level output voltage v cc = 4.75v, i out = 1.6ma l 0.4 v i oz hi-z output current cs = high l 5 m a i source output source current v out = 0v C 25 ma i sink output sink current v out = v cc 45 ma i cc supply current cs = high l 0.1 5 m a cs = low, v cc = 5v l 0.7 1 ma t smpl analog input sample time see figure 1 1.5 clk cycles t conv conversion time see figure 1 10 clk cycles t ddo delay time, clk to d out data valid c load = 100pf l 150 300 ns t en delay time, clk to d out data enabled c load = 100pf l 60 150 ns t dis delay time, cs - to d out hi-z l 170 450 ns t hdo time output data remains valid after clk c load = 100pf 30 ns t f d out fall time c load = 100pf l 70 250 ns t r d out rise time c load = 100pf l 25 100 ns c in input capacitance analog input on-channel 30 pf analog input off-channel 5 pf digital input 5 pf (note 2, 3) e lectr ic al c c hara terist ics reco m e n ded operati n g co n ditio n s u u u u w w symbol parameter conditions min typ max units v cc supply voltage 4.5 6 v f clk clock frequency v cc = 5v 150 250 350 khz t cyc total cycle time f clk = 250khz 74 m s temperature conversion only 144 m s t hdi hold time, d in after clk - v cc = 5v 150 ns t sucs setup time cs before first clk - (see figure 1) v cc = 5v 2 m s t wakeup wakeup time cs before start bit - (see figure 1) v cc = 5v 10 m s temperature conversion only 80 m s t sudi setup time, d in stable before clk - v cc = 5v 150 ns t whclk clock high time v cc = 5v 1.6 m s t wlclk clock low time v cc = 5v 2 m s t whcs cs high time between data transfer cycles v cc = 5v, f clk = 250khz 2 m s t wlcs cs low time during data transfer v cc = 5v, f clk = 250khz 72 m s temperature conversion only 142 m s
4 ltc139 2 reco m e n ded operati n g co n ditio n s u u u u w w the l denotes specifications which apply over the operating temperature range (0 c t a 70 c for commercial grade and C 40 c t a 85 c for industrial grade). note 1: absolute maximum ratings are those values beyond which the life of the device may be impaired. note 2: all voltage values are with respect to gnd. note 3: testing done at v cc = 5v, clk = 250khz and t a = 25 c unless otherwise specified. note 4: temperature integral nonlinearity is defined as the deviation of the a/d code versus temperature curve from the best-fit straight line over the devices rated temperature range. note 5: voltage integral nonlinearity is defined as the deviation of a code from a straight line passing through the actual end points of the transfer curve. note 6: channel leakage current is measured after the channel selection. note 7: see guaranteed temperature limit curves vs temperature range on the first page of this data sheet. typical perfor m a n ce characteristics u w differential nonlinearity power supply voltage mode differential nonlinearity integral nonlinearity power supply voltage mode code 256 1.0 differential nonlinearity error (lsb) 0.5 0 0.5 1.0 320 384 448 512 1392 g01 576 640 704 768 832 f clk = 250khz t a = 25 c code 256 1.0 integral nonlinearity error (lsb) 0.5 0 0.5 1.0 320 384 448 512 1392 g02 576 640 704 768 832 f clk = 250khz t a = 25 c code 256 128 0 1.0 differential nonlinearity error (lsb) 0.5 0 0.5 1.0 384 512 1392 g03 640 768 896 1024 full scale = 1v f clk = 250khz t a = 25 c v cc = 5v code 256 128 0 1.0 integral nonlinearity error (lsb) 0.5 0 0.5 1.0 384 512 1392 g04 640 768 896 1024 full scale = 1v f clk = 250khz t a = 25 c v cc = 5v integral nonlinearity integral nonlinearity differential nonlinearity code 256 128 0 1.0 differential nonlinearity error (lsb) 0.5 0 0.5 1.0 384 512 1392 g05 640 768 896 1024 full scale = 0.5v f clk = 250khz t a = 25 c v cc = 5v code 256 128 0 1.0 integral nonlinearity error (lsb) 0.5 0 0.5 1.0 384 512 1392 g06 640 768 896 1024 full scale = 0.5v f clk = 250khz t a = 25 c v cc = 5v
5 ltc139 2 typical perfor m a n ce characteristics u w input shift register bandgap control and timing cs 4 ltc1392 ?bd serial port v ref = 2.42v v ref = 1v v ref = 0.5v analog input mux 10-bit sar 10 bits c sample v cc 85 gnd temperature sensor v cc gnd d in 1 v ref +v in ? in 6 7 comp 10-bit capacitive dac + + + d out 2 clk 3 block diagra m w pi n fu n ctio n s uuu d in (pin 1): digital input. the a/d configuration word is shifted into this input. d out (pin 2): digital output. the a/d result is shifted out of this output. clk (pin 3): shift clock. this clock synchronizes the serial data. cs (pin 4): chip select input. a logic low on this input enables the ltc1392. gnd (pin 5): ground pin. gnd should be tied directly to an analog ground plane. +v in (pin 6): positive analog differential input. the pin can be used as a single-ended input by grounding C v in . Cv in (pin 7): negative analog differential input. the input must be free from noise. v cc (pin8): positive supply. this supply must be kept free from noise and ripple by bypassing directly to the ground plane. supply current vs sample rate time (sec) 0 temperature ( c) 5 10 15 20 1392 g07 25 70 65 60 55 50 45 40 35 30 25 20 30 v cc = 5v n8 s8 thermal response in stirred oil bath sample frequency (hz) supply current ( m a) 1000 100 10 1 0.1 0.1 10 100 1k 10k 100k 1392 g09 1 v cc = 5v f clk = 250khz t a = 25 c cs low between samples cs high between samples time (sec) 0 temperature ( c) 50 100 150 200 1392 g08 250 70 65 60 55 50 45 40 35 30 25 20 300 v cc = 5v n8 s8 thermal response in still air
6 ltc139 2 test circuits voltage waveforms for t dis d out waveform 1 (see note 1) 2.0v t dis 90% 10% d out waveform 2 (see note 2) cs note 1: waveform 1 is for an output with internal conditions such that the output is high until disabled by the output control. note 2: waveform 2 is for an output with internal conditions such that the output is low until disabled by the output control. ltc1392 ?tc06 applicatio n s i n for m atio n wu u u digital considerations serial interface the ltc1392 communicates with microprocessors and other external circuitry via a synchronous, half-duplex, 3-wire serial interface (see figure 1). the clock (clk) synchronizes the data transfer with each bit being trans- mitted on the falling clk edge and captured on the rising clk edge in both transmitting and receiving systems. the input data is first received and then the a/d conversion result is transmitted (half-duplex). half-duplex operation allows d in and d out to be tied together allowing transmis- sion over three wires: cs, clk and data (d in /d out ). data transfer is initiated by a falling chip select (cs) signal. after the falling cs is recognized, an 80 m s delay is needed for the ltc1392 is a micropower data acquisition system designed to measure temperature, an on-chip power supply voltage and a differential input voltage. the ltc1392 contains the following functional blocks: 1. on-chip temperature sensor 2. 10-bit successive approximation capacitive adc 3. bandgap reference 4. analog multiplexer (mux) 5. sample-and-hold (s/h) 6. synchronous, half-duplex serial interface 7. control and timing logic load circuit for t ddo , t r and t f d out 1.4v 3k 100pf test point ltc1392 ?tc02 voltage waveforms for d out delay time, t ddo clk d out v il t ddo v ol v oh ltc1392 ?tc03 load circuit for t dis and t en d out 3k 100pf test point 5v t dis waveform 2, t en t dis waveform 1 ltc1392 ?tc05 voltage waveforms for d out rise and fall times, t r and t f d out v ol v oh t r t f 1392 tc04
7 ltc139 2 applicatio n s i n for m atio n wu u u msb-first data (msbf = 1) t cyc cs start sel1 sel0 sel1 sel0 msbf t smpl hi-z hi-z filled with zeros d in d out b9 b8 b7 b6 b5 b4 b3 b2 b1 t conv b0 clk t sucs t wakeup t cyc cs start msbf hi-z hi-z ltc1392 ?f01 filled with zeros d in d out b9 b8 b7 b6 b5 b4 b3 b2 b1 t conv b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 clk t sucs t wakeup t smpl figure 1 temperature measurement or a 10 m s delay for other mea- surements, followed by a 4-bit input word which config- ures the ltc1392 for the current conversion. this data word is shifted into the d in input. d in is then disabled from shifting in any data and the d out pin is configured from three-state to an output pin. a null bit and the result of the current conversion are serially transmitted on the falling clk edge onto the d out line. the format of the a/d result can be either msb-first sequence or msb-first sequence followed by an lsb-first sequence. this provides easy interface to msb- or lsb-first serial ports. bringing cs high resets the ltc1392 for the next data exchange. input data word data transfer is initiated by a falling chip select (cs) signal. after cs falls, the ltc1392 looks for a start bit. once the start bit is received, the next three bits are shifted into the d in input which configures the ltc1392 and starts the conversion. further inputs on the d in input are then ignored until the next cs cycle. the four bits of the input word are defined as follows: bit 3 bit 2 bit 1 bit 0 start select 1 select 0 msbf start bit the first logic one clocked into the d in input after cs goes low is the start bit. the start bit initiates the data transfer and all leading zeros which precede this logical one will be ignored. after the start bit is received the remaining bits of the input word will be clocked in. further input on the d in pin are then ignored until the next cs cycle.
8 ltc139 2 applicatio n s i n for m atio n wu u u measurement mode selections the two bits of the input word following the start bit assign the measurement mode for the requested conversion. table 1 shows the mode selections. whenever there is a mode change from another mode to temperature mea- surement, a temperature mode initializing cycle is needed. the first temperature data measurement after a mode change should be ignored. table 1. measurement mode selections select select 1 0 measurement mode 0 0 temperature 0 1 power supply voltage 1 0 differential input, 1v full scale 1 1 differential input, 0.5v full scale msb-first/lsb-first (msbf) the output data of the ltc1392 is programmed for msb-first or lsb-first sequence using the msbf bit. when the msbf bit is a logical one, data will appear on the d out line in msb-first format. logical zeros will be filled in indefinitely following the last data bit to accommodate longer word lengths required by some microprocessors. when the msbf bit is a logical zero, lsb-first data will follow the normal msb-first data on the d out line. conversions temperature conversion the ltc1392 measures temperature through the use of an on-chip, proprietary temperature measurement technique. the temperature reading is provided in a 10-bit, unipolar format. table 2 describes the exact relationship of output data to measured temperature or equation 1 can be used to calculate the temperature. temperature ( c) = output code/4 C 130 (1) note that the ltc1392c is only specified for operation over the 0 c to 70 c temperature range and the ltc1392i over the C 40 c to 85 c range. performance at tempera- tures outside these specified temperature ranges is not guaranteed and errors may be greater than those shown in the electrical characteristics table. table 2. codes for temperature conversion output code temperature ( c) 1111111111 125.75 1111111110 125.50 ... ... 1001101101 25.25 1001101100 25.00 1001101011 24.75 ... ... 0000000001 C 129.75 0000000000 C 130.00 voltage supply (v cc ) monitor the ltc1392 measures supply voltage through the on- chip v cc supply line. the v cc reading is provided in a 10-bit, unipolar format. table 3 describes the exact rela- tionship of output data to measured v cc or equation (2) can be used to calculate the measured v cc . measured v cc = [(output code) ? 4.84/1024] + 2.42 (2) the guaranteed supply voltage monitor range is from 4.5v to 6v. typical parts are able to maintain measurement accuracy with v cc as low as 3.25v. the typical inl and dnl error plots shown on page 4 are measured with v cc from 3.63v to 6.353v. table 3. codes for voltage supply conversion output code supply voltage (v cc ) 1011110110 6.003v 1011110101 5.998v ... ... 1000100010 5.001v ... ... 0110111001 4.504v 0110111000 4.500v
9 ltc139 2 applicatio n s i n for m atio n wu u u differential voltage conversion the ltc1392 measures the differential input voltage through pins + v in and C v in . input ranges of 0.5v or 1v full scale are available for differential voltage measure- ment with resolutions of 10 bits. tables 4a and 4b describe the exact relationship of output data to measured differen- tial input voltage in the 1v and 0.5v input range. equations (3) and (4) can be used to calculate the differential voltage in the 1v and 0.5v input voltage range respectively. the output code is in unipolar format. differential voltage = 1v ? (10-bit code)/1024 (3) differential voltage = 0.5v ? (10-bit code)/1024 (4) table 4a. codes for 1v differential voltage range output input input code voltage range = 1v remarks 1111111111 1v C 1lsb 999.0mv 1111111110 1v C 2lsb 998.0mv ... ... ... 0000000001 1lsb 0.977mv 1lsb = 1/1024 0000000000 0lsb 0.00mv table 4b. codes for 0.5v differential voltage range output input input code voltage range = 0.5v remarks 1111111111 0.5v C 1lsb 499.5mv 1111111110 0.5v C 2lsb 499.0mv ... ... ... 0000000001 1lsb 0.488mv 1lsb = 0.5/1024 0000000000 0lsb 0.00mv thermal coupling/airflow the supply current of the ltc1392 is 700 m a typically when running at the maximum conversion rate. the equiva- lent power dissipation of 3.5mw causes a temperature rise of 0.455 c in the so8 and 0.35 c in pdip packages due to self-heating effects. at sampling rates less than 400 samples per second, less than 20 m a current is drawn from the supply (see typical performance characteristics) and the die self-heating effect is negligible. this ltc1392 can be attached to a surface (such as microprocessor chip or a heat sink) for precision temperature monitoring. the package leads are the principal path to carry the heat into the device; thus any wiring leaving the device should be held at the same temperature as the surface. the easiest way to do this is to cover up the wires with a bead of epoxy which will ensure that the leads and wires are at the same temperature as the surface. the thermal time constant of the ltc1392 in still air is about 22 seconds (see the graph in the typical performance charateristics section). at- taching an ltc1392 to a small metal fin (which also provides a small thermal mass) will help reduce thermal time constant, speed up the response and give the steadi- est reading in slow moving air.
10 ltc139 2 system monitor for two supply voltages and ambient temperature system monitor for relative humidity, supply voltage and ambient temperature 1 2 3 4 8 7 6 5 v cc ? in +v in gnd p1.4 p1.3 p1.2 d in d out clk cs ltc1392 5v output 0v to 1v = 0% to 100% 0.1 m f 0.1 m f 6 1 2 3 9k* 1k* 8 100pf mpu (e.g., 8051) 22m sensor sensor: panametrics #rhs 500pf at rh = 76% 1.7pf/%rh + lm301a 10k 5v 5v 5v ?v ?v ?v 10k 5% rh trim 0.1 m f 0.1 m f 1392 ta04 1 m f 6 2 3 7 4 + lt 1056 0.1 m f 100pf 0.1 m f 0.01 m f 1/4 ltc1043 1/4 ltc1043 1 m f ?v 1k 1% lt1004-1.2 500 w 90% rh trim 470 w 33k 13 12 14 11 17 16 7 8 0.1 m f * 1% film resistor typical applicatio n s u 1 2 3 4 8 7 6 5 v cc ? in +v in gnd p1.4 p1.3 p1.2 d in d out clk cs ltc1392 v out 3.3v v cc ? in +v in pv cc g1 m2 0.1 m f 2.5 m h 15a 0.1 m f ltc1392 ?ta03 10 m f 0.1 m f 1n4148 m3 m1, m2, m3: motorola mtd20n03hl m1 5v g2 shdn shdn r c 7.5k c c 4700pf fb comp gnd 10k trimmed to v out = 3.3v 10k 12k 100pf ltc1430 mpu (e.g., 8051) + c1 220pf 100k 33k 22 w 0.1 m f 10 m f 16v 220 m f 10v 4 c o 330 m f 6.3v 6 + + +
11 ltc139 2 package descriptio n u dimemsions in inches (millimeters) unless otherwise noted. information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. s8 package 8-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) 1 2 3 4 0.150 ?0.157** (3.810 ?3.988) 8 7 6 5 0.189 ?0.197* (4.801 ?5.004) 0.228 ?0.244 (5.791 ?6.197) 0.016 ?0.050 0.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0 ?8 typ 0.008 ?0.010 (0.203 ?0.254) so8 0695 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) bsc dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side * ** n8 package 8-lead pdip (narrow 0.300) (ltc dwg # 05-08-1510) n8 0695 0.005 (0.127) min 0.100 0.010 (2.540 0.254) 0.065 (1.651) typ 0.045 ?0.065 (1.143 ?1.651) 0.130 0.005 (3.302 0.127) 0.015 (0.380) min 0.018 0.003 (0.457 0.076) 0.125 (3.175) min 12 3 4 87 6 5 0.255 0.015* (6.477 0.381) 0.400* (10.160) max 0.009 ?0.015 (0.229 ?0.381) 0.300 ?0.325 (7.620 ?8.255) 0.325 +0.025 0.015 +0.635 0.381 8.255 () *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.010 inch (0.254mm)
12 ltc139 2 ? linear technology corporation 1995 1392f lt/tp 0497 7k ? printed in usa u a o pp l ic at i ty p i ca l linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 l (408) 432-1900 fax: (408) 434-0507 l telex: 499-3977 l www.linear-tech.com 1 2 3 4 8 7 6 5 v cc ? in +v in gnd p1.4 p1.3 p1.2 d in d out clk cs ltc1392 1392 ta05 5v 5v mpu (e.g., 8051) lt1004-1.2 * 1% film resistor ideal output (v) = 11.15mv/ c ?temperature + 1.371 temperature range: 38 c to 80 c 4 c ert-d2fhl103s divider output voltage vs temperature temperature ( c) 20 divider output voltage (v) 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 50 70 30 40 60 80 ideal output (v) = 11.15mv/ c ?temperature + 1.371 actual divider output r2* 1.8k r t = ert ?d2fhl103s assuming 3% b and 10% r to tolerances r1* 6.8k measuring a secondary temperature with an external thermistor related parts part number description comment lt1025 micropower thermocouple cold junction compensator compatible with standard thermocouples (e, j, k, r, s, t) ltc1285/ltc1288 3v micropower 12-bit adcs with auto shutdown differential or 2-channel multiplexed, single supply ltc1286/ltc1298 micropower 12-bit adcs with auto shutdown differential or 2-channel multiplexed, single supply ltc1391 low power, precision 8-to-1 analog multiplexer spi, qspi compatible, single 5v or 3v, low r on , low charge injection lm334 constant current source and temperature sensor 3 pins, current out pin

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