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data sheet rev. 1.20/ august 2011 ZSSC3122 clite ? low voltage capacitive sensor signal conditioner
ZSSC3122 clite? low voltage capacitive sensor signal conditioner ? 2011 zentrum mikroelektronik dresden ag ? rev. 1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. brief description the ZSSC3122 clite? is a cmos integrated circuit for accurate capacitance-to-digital conversion and sensor-specific correction of capacitive sensor sig- nals. digital compensation of sensor offset, sensiti- vity and temperature drift is accomplished via an internal digital signal processor running a correction algorithm with calibration coefficients stored in a non-volatile eeprom. the ZSSC3122 is configurable for capacitive sen- sors with capacitances up to 10pf and a sensitivity of 125af/lsb. it is compatible with both single capa- citive sensors (both terminals must be accessible) and differential capacitive sensors. measured and corrected sensor values can be output as i 2 c ? * , spi, pdm, or alarms. the i 2 c? interface can be used for a simple pc- controlled calibration procedure to program a set of calibration coefficients into an on-chip eeprom. the calibrated ZSSC3122 and a specific sensor are mated digitally: fast, precise, and without the cost overhead of trimming by external devices or laser. features ? maximum target input capacitance: 10pf ? sampling rates as fast as 0.7ms @ 8-bit; 1.6ms @ 10-bit; 5.0ms @ 12-bit; 18.5ms @ 14-bit ? digital compensation of sensor: piece-wise 1 st and 2 nd order sensor compensation or up to 3 rd order single-region sensor compensation ? digital compensation of 1 st and 2 nd order temperature gain and offset drift ? internal temperature compensation reference (no external components) ? programmable capacitance span and offset ? layout customized for die-die bonding with sensor for low-cost, high-density chip-on-board assembly ? ? accuracy as high as 0.25% fso@ -40 to 125c, 3v, 5v, vsupply 10% * i 2 c? is a registered trademark of nxp. ? see data sheet section 1.3 for restrictions. benefits ? minimized calibration costs: no laser trimming, one-pass calibration using a digital interface ? excellent for low-power battery applications interfaces ? i2c? or spi interface?eas y connection to a c ? pdm outputs (filtered analog ratiometric) for both capacitance and temperature ? up to two alarms that can act as full push-pull or open-drain switches physical characteristics ? supply voltage: 1.8 to 5.5v ? typical current consumption 650 a down to 60 a depending on configuration ? typical sleep mode current: 1 a at 85c ? operation temperature: ?40c to +125c ? die or tssop14 package available support ? ZSSC3122 ssc evaluation kit available: ssc evaluation board, samples, software, documentation. support for indus ? trial mass calibration available. quick circuit customiz ation option for large ? prod uction volumes. application: digital output, alarms
ZSSC3122 clite? low voltage capacitive sensor signal conditioner ? 2011 zentrum mikroelektronik dresden ag ? rev. 1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. clite? ZSSC3122 block diagram application: analog output application: differential capacitance input part ordering codes sales code description package ZSSC3122aa1b ZSSC3122 clite? die ? temperature range: -40c to +125c tested dice on un-sawn wafer ZSSC3122aa1c ZSSC3122 clite? die ? temperature range: -40c to +125c tested dice on frame ZSSC3122aa2 ZSSC3122 clite? tssop14 ? temperature range: -40c to +125c ? lead-free package tube: add ?t? to sales code reel: add ?r? ZSSC3122kit ZSSC3122 ssc evaluation kit: comm unication board, ssc evaluation board, sensor replacement board, evaluation software, usb cable, 5 ic samples kit sales and further information www.zmdi.com ssc@zmdi.com zentrum mikroelektronik dresden ag grenzstrasse 28 01109 dresden germany zmd america, inc. 8413 excelsior drive suite 200 madison, wi 53717 usa zentrum mikroelektronik dresden ag, japan office 2 nd floor, shinbashi tokyu bldg. 4-21-3, shinbashi, minato-ku tokyo, 105-0004 japan zmd far east, ltd. 3f, no. 51, sec. 2, keelung road 11052 taipei taiwan phone +49 (0)351.8822.7.772 fax +49 (0)351.8822.8.7772 phone +1 (608) 829-1987 fax +1 (631) 549-2882 phone +81.3.6895.7410 fax +81.3.6895.7301 phone +886 2 2377 8189 fax +886 2 2377 8199 disclaimer : this information applies to a product under development. its characteristics and specifications are subject to change without notice. zentrum mikroelektronik dresden ag (zmd ag) assumes no obligation regarding future manufacture unless otherwise agreed to in writing. the information furnished hereby is believed to be true and accurate. however, under no circumstances shall zmd ag be liable to any customer, licensee, or any other third party for any special, indirect, incident al, or consequential damages of any kind or nature whatsoever arising out of or in any way related to the furnishing, performance, or use of this technical data. zmd ag hereby expressly dis claims any liability of zmd ag to any customer, licensee or any other third party, and any such customer, licensee and any other third party hereby waives any liability of zmd ag for any dama ges in connection with or arising out of the furnishing, performance or use of this technical data, whether based on contract, warranty, tort (including negligence), strict liability, or otherwise.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 4 of 63 contents 1 ic characte ristics ............................................................................................................. ....8 1.1 absolute maxi mum rati ngs ............................................................................................8 1.2 operating c onditi ons ......................................................................................................8 1.3 electrical pa rameters ......................................................................................................9 1.4 current consum ption gr aphs .......................................................................................12 1.4.1 update mode current consumpt ion ........................................................................12 1.4.2 sleep mode current consumpt ion........................................................................... 12 1.5 output pad driv e strengt h ............................................................................................13 1.6 temperature sensor nonlinear it y .................................................................................14 2 circuit desc ription ............................................................................................................ ..15 2.1 signal flow and block diagram ....................................................................................15 2.2 analog front end ..........................................................................................................15 2.2.1 capacitance-to-digit al conver ter .............................................................................15 2.2.2 temperature m easure m ent .....................................................................................19 2.3 digital core ................................................................................................................... 20 3 normal operat ion m ode ..................................................................................................... 20 3.1 power-on s equence ..................................................................................................... 22 3.2 measurement cycle ...................................................................................................... 22 3.3 measurement modes ....................................................................................................23 3.3.1 update m ode ...........................................................................................................23 3.3.2 sleep m ode .............................................................................................................26 3.4 status and diagnostics .................................................................................................28 3.4.1 eeprom error detec ti on and correct ion................................................................29 3.4.2 alarm diag nostics ....................................................................................................30 3.5 output mo des ...............................................................................................................30 3.6 i 2 c and sp i ...................................................................................................................30 3.6.1 i 2 c features and timi ng ..........................................................................................31 3.6.2 spi features and timi ng .........................................................................................32 3.6.3 i 2 c and spi co mmands...........................................................................................33
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 5 of 63 3.6.4 data fetc h (df) .......................................................................................................33 3.6.5 measurement r equest (m r) ...................................................................................35 3.6.6 ready pi n ................................................................................................................36 3.7 pdm (pulse densit y modulat ion) ..................................................................................36 3.8 alarm ou tp ut.................................................................................................................38 3.8.1 alarm regi sters .......................................................................................................38 3.8.2 alarm oper ation....................................................................................................... 38 3.8.3 alarm outp ut c onfigurat ion .....................................................................................40 3.8.4 alarm pola rity ..........................................................................................................40 4 command m ode .................................................................................................................41 4.1 command fo rmat .........................................................................................................41 4.2 command enc odings ....................................................................................................41 4.3 command response and data fe tch ...........................................................................42 5 eeprom ......................................................................................................................... ...46 5.1.1 zmdi configuration register (zmdi_config, eeprom word 02 hex ) ......................48 5.1.2 capac itance analog front end configuration (c_config, eeprom word 06 hex )...49 5.1.3 temperature analog front end configuration (t_config, eepro m word 11 hex )..50 5.1.4 customer configurati on register (cust_config, eeprom word 1c hex ) ................51 6 calibration and signal conditioning math ...........................................................................52 6.1 capacitance signal condition ing ..................................................................................52 6.2 temperature signal compensat ion ..............................................................................53 6.3 limits on coeffi cient r anges ........................................................................................54 7 application circu it ex am ples ..............................................................................................55 7.1 digital output with optional al arms ..............................................................................55 7.2 analog output with optional al arms .............................................................................56 7.3 bang-bang control s ystem ............................................................................................57 7.4 differential input capacit ance .......................................................................................58 7.5 ex ternal refer ence capac itor .......................................................................................59 8 esd/latch-up-pr otection ...................................................................................................59 9 pin configurati on and pa ckage ..........................................................................................60
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 6 of 63 10 test ........................................................................................................................... .........61 11 reliabi lity .................................................................................................................... ........62 12 customiz ation .................................................................................................................. ...62 13 part orderi ng codes ........................................................................................................... 6 2 14 related docu ments ............................................................................................................62 15 glossary ....................................................................................................................... ......62 16 document revisi on history ................................................................................................63 list of figures figure 1.1 best case settings (typical part) ........................................................................................................12 figure 1.2 worst case settings (typical part) ......................................................................................................12 figure 1.3 typical current consumption dur ing sleep mode (no measurements) ..............................................12 figure 1.4 output high drive strength graph ......................................................................................................13 figure 1.5 output low drive strength graph .......................................................................................................13 figure 1.6 first order fit (typical part) ................................................................................................................14 figure 1.7 second order fit (typical part) ...........................................................................................................14 figure 2.1 ZSSC3122 block diagram ...................................................................................................................15 figure 3.1 general operation ............................................................................................................................... 21 figure 3.2 power-on sequence with fast startup bit set in eeprom ...............................................................22 figure 3.3 measurement cycle timing ................................................................................................................23 figure 3.4 measurement sequence in update mode ...........................................................................................24 figure 3.5 i 2 c and spi data fetching in update mode ........................................................................................26 figure 3.6 measurement sequence in sleep mode (only i 2 c, spi, or alarms) ...................................................27 figure 3.7 i 2 c and spi data fetching in sleep mode ...........................................................................................28 figure 3.8 i 2 c timing diagram .............................................................................................................................31 figure 3.9 spi timing diagram .............................................................................................................................32 figure 3.10 i 2 c measurement packet reads .........................................................................................................34 figure 3.11 spi output packet with positive edge sampling .................................................................................35 figure 3.12 i 2 c mr ............................................................................................................................... ................... 35 figure 3.13 spi mr ............................................................................................................................... .................. 36 figure 3.14 example of alarm function ..................................................................................................................39 figure 3.15 alarm output flow chart .....................................................................................................................39 figure 4.1 i 2 c command format ..........................................................................................................................41 figure 4.2 command mode data fetch ................................................................................................................44 figure 7.1 digital output with optional alarms example ......................................................................................55 figure 7.2 analog output with optional alarms example .....................................................................................56 figure 7.3 bang-bang control system example ..................................................................................................57
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 7 of 63 figure 7.4 differential input capacitance example ..............................................................................................58 figure 7.5 ext. reference input capacitance example ........................................................................................59 figure 9.1 ZSSC3122 pin-out diagram ...............................................................................................................60 list of tables table 2.1 selection settings for c ref , and c off , (capacitance ranges are nominal values) ..............................18 table 3.1 cdc resolution and conversion times ..............................................................................................23 table 3.2 update rate settings ..........................................................................................................................24 table 3.3 time periods between capacitance measurements and temperature measurements for different resolution and update rates ..............................................................................................................25 table 3.4 status table ............................................................................................................................... .......... 29 table 3.5 diagnostic detection ............................................................................................................................29 table 3.6 normal operation diagnostic table ....................................................................................................29 table 3.7 output modes ............................................................................................................................... ....... 30 table 3.8 pin assignment for output selections .................................................................................................30 table 3.9 i 2 c parameters ............................................................................................................................... ..... 31 table 3.10 spi parameters ............................................................................................................................... .... 32 table 3.11 i 2 c and spi command types ..............................................................................................................33 table 3.12 low pass filter example for r = 10k ? ................................................................................................37 table 4.1 command list and encodings .............................................................................................................42 table 4.2 response bits ............................................................................................................................... ....... 45 table 4.3 command diagnostic bits ..................................................................................................................45 table 5.1 eeprom word assignments ..............................................................................................................46 table 5.2 zmdi_config bit assignments .............................................................................................................48 table 5.3 c_config bit assignments ...................................................................................................................49 table 5.4 t_config bit assignments ...................................................................................................................50 table 5.5 cust_config bit assignments ..............................................................................................................51 table 7.1 example 1: configuration settings ......................................................................................................55 table 7.2 example 2: configuration settings ......................................................................................................56 table 7.3 example 3: configuration settings ......................................................................................................57 table 7.4 example 4: configuration settings ......................................................................................................58 table 7.5 example 5: configuration settings ......................................................................................................59 table 9.1 storage and soldering condition .........................................................................................................60 table 9.2 ........................................................................................60 ZSSC3122 pin assignments for tssop-14
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 8 of 63 1 ic characteristics 1.1 absolute maximum ratings parameter symbol min typ max units analog supply voltage v dd -0.3 6.0 v voltages at analog i/o ? in pin v ina -0.3 v dd +0.3 v voltages at analog i/o ? out pin v outa -0.3 v dd +0.3 v storage temperature range t stor -55 150 c 1.2 operating conditions see important footnotes at t he end of the following table. parameter symbol min typ max units supply voltage to gnd v supply 1.8 5.5 v ambient temperature range 1 t amb -40 125 ?c output pads/pins drive strength 2 i out 1.5 20 ma external capacitance between v dd pin and gnd c vsupply 100 220 470 nf external capacitance between vcore and gnd?sleep mode c vcore_sm 10 100 nf external capacitance between vcore and gnd?update mode c vcore_um 100 330 nf input capacitance span (full scale values) c 0 2 10 pf external reference capacitance c 1 2 10 pf external isolating capacitance (cc pin to sensor common node) 3 c cc 16 pf i 2 c pull-up resistor 2 r pu 1 2.2 k? sda/miso load capacitance c sda 200 pf 1 caution: if buying die, select the proper package to ensur e that the maximum junction temperature is not exceeded. 2 see section 1.5 for full details on output pad drive strengths. 3 an external isolating capacitor allows a non-galvanic connection to special differentia l or external reference sensor types. cc c could also be used to lower the overall capacitance level to a value that is supported by the ZSSC3122 because it limits the maximum capac itance seen by the ZSSC3122 input to cc even if c0 and c1 have higher values.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 9 of 63 1.3 electrical parameters see important footnotes at t he end of the following table. parameter symbol conditions min typ max units supply current best case settings: * 8-bit, 125ms power down 60 100 update mode curr ent (varies with part configuration) 1 i dd worst case settings: 14-bit, 0ms power down 750 1100 a extra current with pdm enabled * i pdm 150 a -40 to 85c 0.6 1 a sleep mode current 1 i sleep -40 to 125c 1 3 a voltage levels power-on-reset level v por 1.6 1.7 1.75 v active regulated voltage v reg 2.4 2.55 2.7 v capacitance-to-digital converter (cdc) resolution res cdc 8 14 bits excitation frequency of external capacitances c 0 and c 1 (for a system frequency f sys ) f exc f sys /2 khz integral nonlinearity (inl) 2 inl cdc 0% to 90% input, 14-bit 0.2 % differential nonlinearity (dnl) * dnl cdc 0% to 90% input, 14-bit 0.9 lsb eeprom number of erase/write cycles n wri_eep @85?c ? 100k ? data retention t wri_eep @100 ?c ?? 10 year temperature conversion -40 to 125c, 8-bit mode 0.64 0.96 1.6 resolution in c * res temp -40 to 125c, 14-bit mode 0.01 0.015 0.025 c nonlinearity first order fit * , 3 inl cdc -40 to 125c 0.5 1 c nonlinearity second order fit * , 4 inl cdc -40 to 125c 0.2 0.4 c v supply > v reg +0.25v 0.03 0.1 voltage dependency * psr temp 1.8v v supply v reg + 0.25v 1.25 2.25 c/v
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 10 of 63 parameter symbol conditions min typ max units pdm output output range * v pdm_range 10 90 %v supply pdm frequency f pdm f sys /8 khz filter settling time * , 5 t sett 0% to 90% lpfilter 10k ? /400nf 9.2 ms ripple * , 5 v ripp 0% to 90% lpfilter 10k ? /400nf 1.0 mv/v pdm additional error (including ratiometricity error) * e pdm -40 to 125 ? c 0.1 0.5 % digital i/o voltage output level low v ol 0 0.2 v supply voltage output level high v oh 0.8 1 v supply voltage input level low v il 0 0.2 v supply voltage input level high v ih 0.8 1 v supply communication pin input capacitance * c in 10 pf total system capacitive tolerance between parts * c tol all capacitive values in the specification are subject to this variation 10 % trimmed system frequency f sys all timing in this specification is subject to this variation. 1.76 1.85 1.94 mhz frequency variation over voltage and temperature f var all timing in this specification is subject to this variation. 10 % frequency tolerance between parts (at trim temperature) f osc all timing in this specification is subject to this variation. 5 % start-up-time * , 6, 7 power-on (por) to data ready t sta fastest and slowest settings 4.25 55 ms update rate (update mode) * , 6, 7 t resp_up fastest and slowest settings 0.70 165 ms response time (sleep mode) * , 6, 7 t resp_sl fastest and slowest settings 1.25 45 ms parasitic to gnd tolerance including package parasitics (pins c0, cc, and c1) * 10 pf peak-to-peak noise @ output (100 measurements in 14 bit) * n out 5 20 lsb
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 11 of 63 parameter symbol conditions min typ max units accuracy 3v ? 10%, 3.3v ? 10%, 5v ? 10% 0.25 0.75 2.5v ? 10% 0.50 1.25 error, -40 to 125c * , 8, 9,10 ae out 2.0v ? 10% 2.5 %fso * parameter not tested during production but guaranteed by design. 1 see section 1.4 for full details for current consumption in each mode. 2 parameter measured using internal test capacitors (0pf to 7pf). 3 assumes optimal calibration points of 0c and 100c; see section 1.6 for more details. 4 assumes optimal calibration points of -20c, 40c and 100c; see section 1.6 for more details. 5 see section 3.7 for more details. 6 see section 3 for more details. 7 timing values are for a nominal oscillator , for worst case, 10% total frequency variation, multiply by 0.9 (min time) or 1.1 (max time). 8 accuracy specification includes a 2-point temper ature calibration for correcting the internal tc. 9 accuracy specification assumes maximum parasitics of 10pf to ground. 10 accuracy specification does not include pdm errors, see the pdm output electrical parameters for additional errors when using pdm.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 12 of 63 1.4 current consumption graphs part current consumption depends on a number of different factors including voltage, temperature, capacitive input, resolution, and power down time. the best way to calculate the ZSSC3122?s power consumption is to measure the current consumption with t he actual setup. if measurement is not possible, then the graphs in this section can provide a starting point for estimating the current consumption. 1.4.1 update mode current consumption figure 1.1 best case settings (typical part) figure 1.2 worst case settings (typical part) 1.4.2 sleep mode current consumption figure 1.3 typical current consumption during sleep mode (no measurements)
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 13 of 63 1.5 output pad drive strength figure 1.4 output high drive strength graph 20ma max. allowed 0 20 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 vsupply (v) output high drive strength (ma) , cold / best case hot / worst case typical figure 1.5 output low drive strength graph 20ma max. allowed 0 20 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 vsupply (v) output low drive strength (ma) , cold / best case hot / worst case typical
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 14 of 63 1.6 temperature sensor nonlinearity temperature sensor nonlinearity can vary depending on the ty pe of calibration and the selected calibration points. it is highly recommended that a temperature calibration is done with calibration points at least 20c apart from each other. figure 1.6 and figure 1.7 show the resulting nonlinearity error for the full temperature range (-40c to 125 c) using the optimal calibration points, 0c and 100c for a first-order fit and -20c, 40c, and 100c for a second-order fit. figure 1.6 first order fit (typical part) temperature error -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 -50 0 50 100 150 temperature (c) error (c) figure 1.7 second order fit (typical part) temperature error -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 -50 0 50 100 150 temperature (c) error (c)
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 15 of 63 2 circuit description 2.1 signal flow and block diagram as seen in figure 2.1 , the ZSSC3122 comprises three main blocks: the analog core, digital core, and output comm unication. the capacitive input is first sampled by the analog core using a charge-balancing cdc and is adjusted for the appropriate capacitance range using the cdc_offset, and cdc_reference. the digital core corrects the digital sample with an on-chip digital signal processor (dsp), which uses coefficients stored in eeprom for precise conditioning. an in ternal temperature sensor can be used to compensate for temperature effects of the capacitive input. a temperature value ca n also be calibrated and output as a 14-bit reading. the corrected capacitance value can be re ad using four different output types, i 2 c, spi, pdm, and alarms. they can all be directly interfaced with a microcontroller, and optional filtering of t he pdm output can provide a ratiometric analog output. the alarm pins can also be used to control a variety of analog circuitry. figure 2.1 ZSSC3122 block diagram 2.2 analog front end 2.2.1 capacitance-to-digital converter a 1 st order charge-balancing capacitance-to-digital converte r (cdc) is used to convert the input capacitance to the digital domain. the cdc uses a chopper-stabilized de sign to decrease any drift over temperature. the cdc interfaces to the sensor capacitor through the input mu ltiplexer that controls whether the measurement is a capacitance or a temperature measurement. the input mu ltiplexer also allows for two sensor capacitance configurations: a single sensor capacitance or a ratio bas ed differential capacitive sensor, two-sensor, capacitor configuration, where the reference capacitor is part of the sensor. as part of a sw itched-capacitor network the reference capacitor c 1 is driven by a square wave voltage of the frequency f exc (refer to section 1.3 ). the sensor
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 16 of 63 capacitance c 0 is not exposed to dc voltages in order to prev ent aging effects of some sensor types. the con- figuration of the cdc is controlled by programming settings in eeprom word c_config. (see table 5.3 for set tings.) 2.2.1.1. single ended in the case o f a single-sensor capacitor, the cdc output is proportional to the ratio of the sensor capacitor to an internal reference capacitor ( c ref ). this internal reference capacitor value can be adjusted using the 3-bit trim cdc_reference (bit settings in table 5.3 ). to optimize the measured end-resolution further, another internal cap acitor ( c off ) allows the subtraction of a defined offset capaci tance using the 3-bit trim cdc_offset (bit setting in table 5.3 ). equations (1) to (2) describe the cdc output for a single se n sor capacitance measurement. select the values of cdc_offset, and cdc_referen ce by using the tables in section 2.2.1.4 . ref off sensor c cc z )( 0 ? ? (1) (2) sensor res ccd z z ?? 2 with (3) pf1offset_cdc44.1c off ? ?? and (4) pf1 reference_cdc44.1c ref ? ?? whe re: symbol description z sensor measured sensor ratio, must be in the range [0 to 1] c 0 input sensor capacitance c off zero shift of cdc c ref reference capacitance z cdc digital raw converted capacitance value res programmable cdc resolution of 8, 10, 12, or 14 bits (bit setting in table 5.3 ) cdc_offset cdc offset trim setting (selection see section 2.2.1.4 and bit setting see table 5.3 ) cdc_reference cdc reference setting (selection see section 2.2.1.4 and bit setting see table 5.3 )
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 17 of 63 2.2.1.2. single ended with external reference some sen sors include an external reference capacitor as pa rt of the sensor construction. if the external reference capacitance ( c 1 ) is constant or increases with in creasing input sensor capacitance ( c 0 ), then use cdc output equations (5) to (7). in this case the cdc_reference should be set to zero (bit setting in table 5.3 ). 1 0 )( c cc z off sensor ? ? (5) sensor res ccd z z ?? 2 (6) (7) pf1offset_cdc44.1c off ? ?? whe re symbol description z sensor measured sensor ratio, must be in the range [0 to 1] c 0 input sensor capacitance c off zero shift of cdc c 1 external reference capacitance z cdc digital raw converted capacitance value res programmable cdc resolution of 8, 10, 12, or 14 bits (bit setting in table 5.3 ) cdc_offset cdc offset trim setting (selection see section 2.2.1.4 and bit setting see table 5.3 ) 2.2.1.3. differential a differential cap acitive sensor includes two capacitors c 0 and c 1 that are captured as a ratio. the differential sensor is built so that the sensor input capacitance c 0 increases while the external reference capacitance c 1 decreases over the input signal range, but the total sum always remains constant. equations describe the cdc output for a differential sensor capacitance measurem ent. the cdc_reference and cdc_offset capacitor trim bits must be set to zero, and the differential bit must be set to one. (see table 5.3 for bit numbers and set tings).the sum of c 0 and c 1 must not be bigger than the maximum input range of 10pf, except when cc is used as a decoupling capacitor. in differential mode special sensor types can allow a non- galvanic connection with an external isolating capacitor c cc between the sensor and the cc pin to avoid wear caused by mechanical moving parts.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 18 of 63 (8) ?? 10 0 cc c z sensor ? ? (9) sensor res cdc z z ?? 2 symbol description z sensor measured sensor ratio, must be in the range [0 to 1] c 0 input sensor capacitance (moves in the opposite direction of c 1 ) c 1 external reference capacitance (mov es in the opposite direction of c 0 ) z cdc digital raw converted capacitance value res programmable cdc resolution of 8, 10, 12, or 14 bits (bit setting in table 5.3 ) 2.2.1.4. capacitive range selection for si ngled ended sensors use table 2.1 as guidance to select appropriate values for the cdc ( c off ) and ( c ref ) for a particular capacitanc e input range. the cdc_offset and cdc_refe rence bits are fou nd in eeprom word c_config. (see table 5.3 for bit numbers). using table 2.1 , the cdc input range can be adjusted to optimize the coverage of the sensor signal and offset values to gi ve the maximum sensor span that can be processed without losing resolution. choose a range by fitting the input sens or span within the narrowest range in the table, but note that these tables are only approximate, so the range should be experimentally chosen with the actual setup. also note that since internal capacitance values can vary over proce ss (see spec parameter c tol in section 1.3 ), the minimum and maximum sensor span should be at least 10% within the min and max of the chosen range respectively. note: a c ref setting of 0 (marked with * in the following tables) is only supported with an external reference capacitor (c1) for single-ended sensors. c1 capacitance values should be within the defined. table 2.1 selection settings for c ref , and c off , (capacitance ranges are nominal values ? ) 0 0.0 c1 0.0 1.4 0.0 2.9 0.0 4.3 0.0 5.8 0.0 7.2 0.0 8.6 0.0 10.1 1 1.4 c1 1.4 2.9 1.4 4.3 1.4 5.8 1.4 7.2 1.4 8.6 1.4 10.1 1.4 11.5 2 2.9 c1 2.9 4.3 2.9 5.8 2.9 7.2 2.9 8.6 2.9 10.1 2.9 11.5 2.9 13.0 3 4.3 c1 4.3 5.8 4.3 7.2 4.3 8.6 4.3 10.1 4.3 11.5 4.3 13.0 4.3 14.4 4 5.8 c1 5.8 7.2 5.8 8.6 5.8 10.1 5.8 11.5 5.8 13.0 5.8 14.4 5.8 15.8 5 7.2 c1 7.2 8.6 7.2 10.1 7.2 11.5 6 8.6 c1 8.6 10.1 8.6 11.5 8.6 13.0 7 10.1 c1 10.1 11.5 10.1 13.0 10.1 14.4 34567 cdc_offset not recommended prohibited cdc_reference 3-bit set 0* 1 2 ? production caused toleranc es can change the nominal capacitance values by ? 10%
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 19 of 63 2.2.2 temperature measurement the temperature signal comes from an internal ptat (proport ional to absolute temperature) circuit that is a meas- ure of the die temperature. the ptat ( v ptat ) voltage is used in the cdc to charge an internal capacitor ( c t ), while the bandgap voltage (v bg ) is used to charge the offset and the reference trimmable capacitors. the cdc temperature output (z temp ) is defined by equations (10) to (13): tref toff t bg ptat res temp c ccvv z ?? ?? (10 ) with (11) pf1trim_temp44.1c t ? ?? pf1offset_cdc44.1c toff ? ?? with (12 ) and (13) pf1 reference_cdc44.1c tref ? ?? symbol description z temp measured internal temperature res programmable cdc resolution of 8, 10, 12, or 14 bits (bit setting in table 5.4 ) v ptat internal ptat voltage v bg internal bandgap voltage c t temperature measurement capacitor c toff temperature cdc zero shift c tref temperature reference capacitance temp_trim temperature trim setting (bit setting in table 5.4 ) cdc_offset cdc offset trim setting (bit setting in table 5.4) cdc_reference cdc reference setting (bit setting in table 5.4) note: the factory settings for temp_trim, cdc_offset, and cdc_reference are optimized for the full temperature range of -40c to 125c guaranteeing a minimum effective resolution of 13 bits when 14 bits of reso- lution is selected. unless a different temperature range is needed, it is strongly recommended that these settings not be changed.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 20 of 63 2.3 digital core the digital core provides control logic for the analog fr ont-end, performs input signal conditioning, and handles external communication. a digital signal processor (dsp) is used for conditioning and correcting the converted sensor and temperature inputs. the dsp can correct for up to a two-region piece-wise non-linear sensor input, and up to a second order non-linear temperature input. alternat ively a third-order correction of the sensor input for one region and up to a second-order non-linear temperature input can be selected. refer to section 6 for details on the signal conditioning and correction math. the analog front-end configuration and correction coefficients for both the capacitive sensor and the temperature sensor are stored in an on-chip eeprom (see section 5 ). four different types of outputs are available: i 2 c, spi, pdm, and the alarms. these output modes are used in combination with the two measurement modes: update mode and sleep mode. for a full description of normal operation in each mode, refer to section 3 . the ZSSC3122 has an i nternal 1.85 mhz te mperature-compensated o scillator that provides the time base for all operations. when vdd exceeds the por level, the reset signal de-asserts and the clock generator starts. see section 3.1 for the subsequent power-up sequence. the exact cl ock fre quency influences the measurement cycle time (see the frequency variation spec in section 1.3 ). to minimize the oscilla tor erro r as the vdd voltage changes, an on-chip regulator supplies the osc illator block. 3 normal operation mode figure 3.1 gives a general overview of ZSSC3122 operati on. details of operation, including the power-up sequence, measurement modes, output modes, diagnost ics, and commands, are given in the subsequent sections.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 21 of 63 figure 3.1 general operation update mode ( i 2 c, spi, pdm, or alarms ) sleep mode ( i 2 c, spi, or alarms ) command received command received (i 2 c/spi only) no command mode (no measurement cycle. full command set is available.) yes start_nom no , after command window ex p ires ( 3 ms / 10 ms ) command = start_cm? mr measurement request df data fetch command received. command = start_nom? execute command update rate period over or command received? update period over yes perform measurement no fetch data normal operation mode perform initial measurement. start_cm command received power down (wait for command) command = i 2 c df or spi df? fetch data command = i 2 c mr or spi mr? no yes power down (wait for command.) no yes perform measurement yes command = i 2 c df or spi df? update digital output register, pdms, & alarms powe r -on reset update digital output register & alarms power down
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 22 of 63 3.1 power-on sequence figure 3.2 shows the power-on sequence of the ZSSC3122. on system power-on reset (por), the ZSSC3122 wakes as an i 2 c device regardless of the outpu t protocol programmed in eeprom. after power-on reset, the ZSSC3122 enters the command window. it then waits for a start_cm command for 3ms if the fast_startup eeprom bit is set or 10ms otherwise (see table 5.5 ). if the ZSSC3122 receives the start_cm command during the comm and window, it enters and remains in command mode. command mode is primarily used in the calibration environment. see section 4 for details on command mode. if during the power-on sequence, the command window expires without receiving a start_cm or if the part receives a start_nom command in command mode, the dev ice will immediately assume its programmed output mode and will perform one complete measurement cycle. timing for the initial measurement is described in section 3.2 . at the end of the capacitance dsp calculation, the first data is written to the output regi ster. beyond this point, conversions are performed according to t he programmed measurement mode settings (see section 3.3 ). figure 3.2 power-on sequence with fast startup bit set in eeprom measurement cycle power applied to device. command window starts after a short power-on-reset window. 1 s t corrected signal measurement written to output register (i 2 c, spi, pdms, alarms) por command window capacitance conversion ( ca p conv ) 3ms por when the fast startup bit is not set in eeprom, the command window is 10ms. temperature conversion temp dsp ca lculation cap dsp ca lculation ( tem p conv ) ( tem p calc ) ( ca p calc ) note : see section 3.2 for timing of the measurement cycle. tim ing values shown are typical; for the worst case values, multiply by 1.1 (nominal frequency 10%). 3.2 measurement cycle figure 3.3 shows a typical measurement cycle. at the start of a measurement, there is a small wakeup period and then an internal temperature conversion/temperature dsp calculation is performed followed by a capacitance conversion/capacitance dsp calculation. the length of these conversions depends on the setting of the resolution bits (see table 3.1 ). the resolution can be found in eeprom words c_config and t_config (see table 5.3 and table 5.4 for bit numbers). each conversion cycle is followed by a dsp calculation, which uses the prog rammed calibration coefficients to calculate corr ected temperature and capacitance measurements. in update mode, a temperature conversion is not perform ed every measurement cycle because it is considered a slower moving quantity. in this case, the measurement cycle timing is the same as figure 3.3 without the temper- ature conve rsion/ temperature dsp calculation (see section 3.3.1 for more information).
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 23 of 63 figure 3.3 measurement cycle timing legend: timing for 8-bit resolution timing for 10-bit resolution 0.30ms ti ming for 12-bit resolution 1.15ms ti ming for 14-bit resolution 4.5ms corrected signal measurement written to output register (i 2 c, spi, pdm, or alarms) temperature conversion (temp conv) 18.0ms 0.30m s wakeup 0.10ms temperature dsp calculation (temp calc) capacitance conversion (cap conv) capacitance dsp calculation (cap calc) 0.25m s 0.30ms 1.15ms 4.50ms 18.0ms table 3.1 cdc resolution and conversion times eeprom encoding cdc resolution (bits) temperature conversion time (ms) capacitance conversion time (ms) 00 b 8 0.30 0.30 01 b 10 1.15 1.15 10 b 12 4.50 4.50 11 b 14 18.0 18.0 3.3 measurement modes the ZSSC3122 can be programmed to operate in either sleep mode or update mode. the measurement mode is selected with the measurement_mode bit in the zmdi_config eeprom word (see table 5.2 ). in update mode, measurement s are taken at a fixed, selectable rate (see section 3.3.1 ). in sleep mode, the part waits for com- mand s from the master before taking measurements (see section 3.3.2 ). figure 3.1 shows the differences in operation bet ween the two measurement modes. 3.3.1 update mode in update mode, the digital core will perform conversions at an update rate selected with the update_rate bits in the zmdi_config eeprom word (see table 5.2 ). table 3.2 shows the power-down periods between conversions for the fou r update_rate settings. the benefit of slower update rates is power savings. update mode is compat- ible with all the different output modes; i 2 c, spi, pdms, and the alarms. as shown in figure 3.4 , at the completion all time values shown are typical; for the worst case values, multiply by 1.1 (nominal frequency 10%).
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 24 of 63 of a measurement cycle, the digital output register, pd ms, and/or alarms will be updated before powering down. when the power-down period expires, the ZSSC3122 will wake up and perform another measurement cycle. if the part is programmed for the fastest update rate, ther e is no power down period, and measurements happen continuously. table 3.2 update rate settings ** update_rate power down period (ms) 00 b 0 01 b 5 10 b 25 11 b 125 figure 3.4 measurement sequence in update mode wakeup temp conv cap calc cap conv write new corrected signal measurement to output register (i 2 c, spi, pdms, alarms) wakeup clite? core activity cap conv write new corrected signal measurement to output register (i 2 c, spi, pdms, alarms) power down period depends on selected update rate power down cap calc cap conv power down cap calc write new corrected signal measurement to output register (i 2 c, spi, pdms, alarms) wakeup power down temperature is measured after every sixth capacitive measurements temp calc note : see section 3.2 for measurement cycle timing. to calculate the total time between capacitive measur ements in update mode, add the measurement cycle timing from section 3.2 and the power down timing from table 3.2 . typical settings might be a capacitance measure- ment with a resol ution of 12-bits. in this example, the time between measurements = (4.5ms+ 0.1ms+ 0.3ms) + (power down period). table 3.3 sho ws the time between measurements for the different update rate settings and bit resolutions. temperature measurements are performed every six capacitive measurements. the actual frequency of temperature conversions varies with the update ra te and afe configuration settings. as shown in figure 3.4 whe n a temperature measurement is performed, a capaci tance measurement occurs immediately after, so the total measurement cycle time is increased by the l ength of the temperature c onversion/temperature dsp calculation. ** all time values shown are typical; for the worst case values, multiply by 1.1 (nominal frequency 10%).
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 25 of 63 to calculate the total time between temperature measurem ents in update mode, take the time between capaci- tive measurements as calculated in the above text and mu ltiply that number by six (there are six capacitive mea- surements to every temperature measurement) and t hen add the temperature conv ersion time/temperature dsp calculation time from table 3.1 for exampl e a temperature measurement with a resolution of 12-bits ha s a conversion time/dsp calculation time of 4.5ms +0.25ms (from table 3.1 ) continuing with the above example (12- bit cap acitive measurement) the time between temperature measurements is (capacitance update time * 6) + 4.75ms. table 3.3 time periods between capacitance measurements and temperature measurements for different resolution and update rates total time between capacitance measurements (ms) total time between temperature measurements (ms) cdc resolution (bits) update rate 00 b update rate 01 b update rate 10 b update rate 11 b update rate 00 b update rate 01 b update rate 10 b update rate 11 b 8 0.70 5.70 25.70 125.70 4.75 34.75 154.75 754.75 10 1.55 6.55 26.55 126.55 10.70 40.70 160.70 760.70 12 4.90 9.90 29.90 129.90 34.15 64.15 184.15 784.15 14 18.40 23.40 43.40 143.40 128.65 158.65 278.65 878.65 3.3.1.1. data fetch in update mode in update m ode, i 2 c and spi are used to fetch data from the digital output register using a data fetch (df) com- mand (see section 3.6.3 ). dete cting when data is ready to be fetched can be handled either by polling or by monitoring the ready pin (see section 3.6.6 for details on the ready pin). the st atu s bits of a df tell whether or not the data is valid or stale (see section 3.4 regarding the status bits). as shown in figure 3.5 after a measurement cycle is complete, valid data can be fetched. if the next data fetch is performed too early, the data will be the same as the previous fetch with stale status bits. as shown in figure 3.5 , a rise on the ready pin can also be used to tell when valid data is ready to be fetched.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 26 of 63 figure 3.5 i 2 c and spi data fetching in update mode ready pin power down period depends on selected update rate clite ? core ac tivity temp conv write ne w corrected signal measurement to output register (i 2 c or spi) stale values i 2 c/spi df i 2 c/spi df valid read occurs write new corrected signal measurement to output register (i 2 c or spi) power down stale values i 2 c/spi df i 2 c/spi df cap conv power down cap calc serial interface activity i 2 c/spi df valid read occurs valid read occurs cap conv cap calc cap conv cap calc power down wakeup wakeup wakeup temp calc write new corrected signal measurement to output r egister (i 2 c or spi) note : see section 3.2 for timing of measurements. 3.3.2 sleep mode in sleep mode, the digital core will only perform c onversions when the ZSSC3122 receives a measurement request command (mr); otherwise, the ZSSC3122 is al ways powered down. measurement request commands can only be sent using i 2 c or spi, so pdm is not available. the alarms can be used in sleep mode but only in combination with i 2 c or spi. more details about mr commands in sleep mode operation can be found in section 3.3.2.1 . not e: sleep mode power consumption is significantly lowe r than update mode power consumption (see section 1.3 for exact values). figure 3.6 shows the measurement and communication sequ e nce for sleep mode. the master sends an mr command to wake the ZSSC3122 from power down. a fter the ZSSC3122 wakes up, a measurement cycle is performed consisting of both a temperature and a capa citance conversion followed by the dsp correction calculations.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 27 of 63 at the end of a measurement cycle, th e digital output register and alarms will be updated before powering down. an i 2 c or spi data fetch (df) is performed during the power-down period to fetch the data from the output regis- ter. in i 2 c the user can send another mr to start a new measur ement cycle without fetching the previous data, but in spi, a df must be done before another mr can be sent. after the data has been fetched, the ZSSC3122 remains powered down until the master sends an mr command. the timing for measurements can be found in section 3.2 . figure 3.6 measurement sequence in sleep mode (only i 2 c, spi, or alarms) note : see section 3.2 for timing of measurements. 3.3.2.1. data fetch in sleep mode in sleep mod e, i 2 c and spi are used to request a measurement wi th a mr command and to fetch data from the digital output register using a data fetch (df) command (see section 3.6.3 ). as shown in figure 3.7 , after a measurement cycle is complete, valid data can be fetche d. the preferred method of detecting valid data is to wait for a rise on the ready pin (see section 3.6.6 for details on the ready pin). if the rea dy pin is not available, the user should wait for the measurements to complete before performing the df (see section 3.2 for measurement timing). the status bits of the df can be u sed to tell whether the data is valid or stale (see section 3.4 regarding the status bits), but polling for the result should not be done as the serial comm unication causes increased noise in the system and can result in reduced conv ersion accuracy. if the next data fetch is performed too early , the status bits will be stale and the data will be invalid. wakeup command wakes clite tm ZSSC3122 clite tm core activity serial interface activity cap calc write new corrected signal measurement to output register (i 2 c, spi, alarms) mr df cap conv temp conv power down power down valid read occurs temp calc
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 28 of 63 figure 3.7 i 2 c and spi data fetching in sleep mode power down command wakes clite? ZSSC3122 clite? core activity serial interface activity write new corrected signal measurement to output register (i 2 c or spi) power down stale values valid read occurs mr df df cap conv temp conv wakeup ready pi n cap calc temp calc note : se e section 3.2 for timing of measurements. 3.4 status and diagnostics status bits (the two msbs of the fetched high data byte, see table 3.4 ) are provided in i 2 c and spi but not in pdm. the status bits are used to indicate the current stat e of the fetched data. diagnostic detection is available in i 2 c, spi and pdm. in i 2 c and spi diagnostics are reported as a satu rated high capacitance and temperature output (see table 3.5 ). in pdm, diagnostics are reported as a ra ile d high output level for both pdm_c (capacitive pdm) and pdm_t (temperature pdm). if a diagnostic value is reported then one or more of the errors shown in table 3.6 occurred in normal operation. configuration eeprom di agnostics are det ected at initial power-u p of the ZSSC3122 or a wakeup in sleep mode and are permanent diagnostics. all other diagnostics are detected during a measurement cycle and reported in the subsequent data fetch for i 2 c or spi or output register update for pdm.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 29 of 63 table 3.4 status table status bits (i 2 c or spi) pdm output definition 00 b clipped normal output valid data: da ta that has not been fetched since the last measurement cycle. 01 b not applicable stale data: data that has already been fetched since the last measurement cycle. note : if a data fetch is performed before or during the first measurement after power-on reset, then stale will be returned, but this data is actually invalid since the first measurement has not been completed. 10 b not applicable command mode: the ZSSC3122 is in command mode. 11 b not used not used table 3.5 diagnostic detection i 2 c or spi output pdm output definition saturated output 3fff h high output (railed) level a diagnostic has occurred in normal operation (see table 3.6 ). table 3.6 normal operation diagnostic table diagnostic type definition configuration error perman ent an eeprom or ram parity error o ccurred in the init ial loading of the configuration registers. ram parity error transient a ram parity error o ccurred during a microcontroller instruction in the last measurement cycle. eeprom error transient a ded eeprom error o ccurred in the last m easurement cycle (see section 3.4.1 ). math warning transient an internal math overfl ow has occurred in the last measurement cycle and the output might be invalid. 3.4.1 eeprom error detection and correction the contents of the eeprom are protected via error checking and correction (ecc). each of the 32 16-bit words contains 6 parity bits enabling single-bit error correc tion and double-bit error detection (sec and ded) per word. in command mode both sec and ded errors are reported in the response byte (see section 4.3 ). if the fetched eeprom dat a has a ded error then the fetched data will be incorr ect; however, if a sec error was re ported then the fetched data has been corrected, and it is the user?s choice to write the data ba ck to attempt to correct the error. during normal operation mode, a diagnostic will be flagged on any ded error, but an sec error will be automatically corrected and not flagged as a diagnostic.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 30 of 63 3.4.2 alarm diagnostics the alarm outputs do not report diagnostics. if diagnostic s are needed with alarm outputs, then either digital or pdm outputs must also be used. 3.5 output modes the ZSSC3122 has four different output modes as shown in table 3.7 . see the corresponding reference sections for spe cifics on each mode. table 3.7 output modes output mode reference sections i 2 c read only spi section 3.6 pdm section 3.7 alarms section 3.8 as illustrated in the pin configuration in section 9 , the output communication modes share pins. the output_sele ction bits in eeprom word zmdi_config (see section 5.1.1 ) select which of these outputs will be enabl ed. table 3.8 shows the pin configuration for the different out put selections. table 3.8 pin assignment for output selections output selection i 2 c (001 b ) spi (011 b ) pdm_c (100 b ) pdm_c+t (110 b ) pin 08 alarm_ low alarm_low alarm_low pdm_t pin 09 alarm_high ala rm_high alarm_hi gh alarm_high pin 10 ready ready pdm_c pdm_c pin 12 sda miso sda sda pin 13 scl sclk scl scl pin 14 no input ss no input no input 3.6 i 2 c and spi two wire i 2 c and three-wire read-only spi are available for fetching data from the ZSSC3122. i 2 c is used to send calibration commands to ZSSC3122. to choose i 2 c or spi, set the corresponding output_selection bits in eeprom word zmdi_config.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 31 of 63 3.6.1 i 2 c features and timing the ZSSC3122 uses an i 2 c-compatible communication protocol ?? with support for 100khz and 400khz bit rates. the ZSSC3122 i 2 c slave address (00 h to 7f h ) is selected by the device_id bits in the cust_config eeprom word (see table 5.5 for bit assignments). the device will respond only to this address if the communication lock is set by programming 011 b in the comm_lock bits in the zmdi_config eeprom word (see table 5.2 for bit assignm ents); otherwise, the device will respond to all i 2 c addresses. the factory setting for the i 2 c slave address is 28 h with comm_lock set. see figure 3.8 for the i 2 c timing diagram and table 3.9 for definitions of the parameters shown in the diagram. figure 3.8 i 2 c timing diagram sd a scl t hdst a t hddat t low t sudat t high t sust a t hdst a t susto t bus table 3.9 i 2 c parameters parameter symbol min typ max units scl clock frequency f scl 20 1 400 khz start condition hold time relative to scl edge t hdsta 0.1 ? s minimum scl clock low width 2 t low 0.6 ? s minimum scl clock high width 2 t high 0.6 ? s start condition setup time relative to scl edge t susta 0.1 ? s data hold time on sda re lative to scl edge t hddat 0 0.5 ? s data setup time on sda re lative to scl edge t sudat 0.1 ? s ?? for more details, refer to http://www.standardics.nxp.com/literature/ books/i2c/pdf/i2c.bus.specificat ion.pdf or other websites for this specification.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 32 of 63 t bus t low sclk miso ss hiz t hdss t high t clkd t suss hiz t clkd parameter symbol min typ max units stop condition setup time on scl t susto 0.1 ? s bus free time between stop condition and start condition t bus 1 ? s 1 the minimum frequency of 20khz applies to calibration/test only (required to meet command window timing). there is no minimum for normal operation mode. 2 combined low and high widths must equal or exceed minimum scl period. 3.6.2 spi features and timing spi is available only as half duplex (read-only from the ZSSC3122). spi speeds of up to 800khz can be supported. the spi interface can be programmed to allow the master to sample miso on the falling-edge or rising-edge of scl via the spi_phase bit in eeprom word cust_config (see table 5.5 for bit assignments). see figure 3.9 for the spi timing diagram and table 3.10 for definitions of the parameters shown in the timing diagram. figure 3.9 spi timing diagram table 3.10 spi parameters parameter symbol min typ max units sclk clock frequency f scl 50 800 khz ss drop to first clock edge t hdss 2.5 ? s minimum sclk clock low width 1 t low 0.6 ? s minimum sclk clock high width 1 t high 0.6 ? s clock edge to data transition t clkd 0 0.5 ? s
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 33 of 63 parameter symbol min typ max units rise of ss relative to last clock edge t suss 0.1 ? s bus free time between rise and fall of ss t bus 2 ? s 1 combined low and high widths must equal or exceed minimum sclk period. 3.6.3 i 2 c and spi commands as detailed in table 3.11 , there are three types of commands which allow the user to interface with the zssc312 2 in the i 2 c or spi modes. table 3.11 i 2 c and spi command types type description communication supported reference sections data fetch (df) used to fetch data in any digital mode i 2 c and spi section 3.6.4 measurement request (mr) used to st art measurements in sleep mode i 2 c and spi section 3.6.5 calibration commands used in command mode during the calibration process i 2 c only section 4.2 3.6.4 data fetch (df) the data fetch (df) command is used to fetch data in any digital output mode. with the start of communication (for i2c after reading the slave address; for spi at the falling edge of ss) t he entire output packet will be loaded in a serial output register. the register will be updated a fter the communication is finished. the output is always scaled to 14 bits independent of the programmed reso lution. the ordering of the bits is big-endian. 3.6.4.1. i 2 c data fetch an i 2 c data fetch command starts with the 7-bit slave address and the 8 th bit = 1 (read). the ZSSC3122 as the slave sends an acknowledge (ack) indicating success. the number of data bytes returned by the ZSSC3122 is determined by when the master send s the nack and stop condition. figure 3.10 shows examples of fetching two and th ree bytes respectively. the full 14 bits of capacitive data are fetched in the first two bytes. the msbs of the first byte are the status bits. if temperature data is needed, additional temperature bytes can be fetched. in figure 3.10 , the three-byte data fetch retu rns 1 byte of temperature data (8-bit accuracy ) after the capacitive data. a fourth byte can be fetched where the six msbs of the fetched byte are the six lsbs of a 14-bit temperature measurement. the last two bits of the fourth byte are undetermined and should be masked off in the application.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 34 of 63 figure 3.10 i 2 c measurement packet reads i 2 c df ? 3 bytes: slave returns 2 capacitance data bytes & temperature high byte (t[13:6]) to master device slave address [6:0] cap. data [13:8] cap. data [7:0] device slave address [6:0] cap. data [13:8] cap. data [7:0] temp. data [13:6] i 2 c df ? 2 bytes: slave returns only capacitance data to the master in 2 bytes 2 2 slave address bit (example: bit 2) command or data bit (example: bit 2) status bit start condition stop condition acknowledge (ack) not acknowledge read/write (nack) (read = 1) s a s r n wait for slave ack master ack master ack master nack 14 13 11 12 10 8 9 a 6 5 7 3 4 2 n 1 0 6 s 5 2 1 r 0 a 14 13 15 11 12 10 8 9 a 6 5 7 3 4 2 a 1 0 s 6 s 5 4 2 3 1 r 0 a 15 6 5 7 3 4 2 s n 1 0 4 3 3.6.4.2. spi data fetch by default th e spi interface will have data change after the falli ng edge of sclk. the master should sample miso on the rising (opposite) edge of sclk. this is configurable via the spi_phase bit in eeprom word cust_config (see table 5.5 for bit assignments). the spi protocol can handle high and low polarity of the clock line witho ut configuration change. as seen in figure 3.11 the entire output packet is 4 bytes (32 bits). t he high capacitive data byte comes first, followed by the low byte. then 14 bits of corrected temper ature (t[13:0]) are sent: firs t the t[13:6] byte and then the {t[5:0],xx} byte. the last 2 bits of the final byte are undetermined and should be masked off in the application. if the user only requires the corrected capacitance value, the read can be terminated after the 2 nd byte. if the cor- rected temperature is also required but only at an 8- bit resolution, the read can be terminated after the 3 rd byte is read.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 35 of 63 figure 3.11 spi output packet with positive edge sampling hiz s1 s0 c13 c12 c7 c6 c0 t13 t12 t1 t0 hiz ? ? ? ? ? ? sclk miso ss x packet = [ {s(1:0),c(13:8)}, {c(7:0)} , {t(13:6)},{t(5:0),xx}] where s(1:0) = status bits of packet ( normal, command, busy, diagnostic) c(13:8) = upper 6 bits of 14-bit capacitance data. c(7:0) = lower 8 bits of 14-bit capacitance data. t(13:6) = corrected temperature data (i f application does not require corrected temperature, terminate read early) t(5:0),xx =. remaining bits of corrected temperature data for full 14-bit resolution hiz = high impedance 3.6.5 measurement request (mr) a measurement request (mr) is a sleep-mode-only command sent by the master to wake up the ZSSC3122 and start a new measurement cycle in both i 2 c and spi modes. see section 3.3.2 for more information on sleep mode. 3.6.5.1. i 2 c measurement request the i 2 c mr is used to wake up the device in sleep mode and start a complete measurement cycle starting with a temperature measurement, followed by a capacitance measurement, followed by the dsp calculations, and then the results are written to the digital output register. as shown in figure 3.12 , the communication contains only the slave add ress and the write bit (0) sent by the master. after the ZSSC3122 responds with the slave ack, the master creates a stop condition. note: the i 2 c mr function can also be accomplished by sending ?don?t care? data after the address instead of immediately sending a stop bit. figure 3.12 i 2 c mr i 2 c mr ? measurement request: slave starts a measurement cycle s 2 start condition stop condition acknowledge (ack) slave address bit read/write bit (example: bit 2) (example: write = 0) w s a device slave address [6:0] 6 s 5 4 2 3 1 w 0 a wait for slave ack s
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 36 of 63 3.6.5.2. spi measurement request the spi m r is used to wake up the device in sleep mode and start a complete measurement cycle starting with a temperature measurement/temperature d sp calculation, followed by a capacitance measurement / capacitance dsp calculations, and then the results are writt en to the digital output register. as shown in figure 3.13 , executing an spi mr comman d is a read of 8 bits , ignoring the data that is returned. note : the spi mr function can also be accomplished by performing a full spi data fetch (see section 3.6.4.2 ) and ign oring the invalid data that will be returned. figure 3.13 spi mr sclk miso ss x x ignore data 3.6.6 ready pin a rise on the ready pin indicates that new data is ready to be fetched from either the i 2 c or spi interface. the ready pin stays high until a data fetch (df) command is sent (see section 3.6.3 ); it stays high even if additional measurement s are performed before the df. the ready pin?s output driver type is selectable as either full push-pull or open drain via the ready_open_drain bit in eeprom word cust_config (see table 5.5 for bit assignments and settings). point-to-point communication most li kely uses the full push-pull driver. if an application requires interfacing to multiple parts, then the open drain option can allow for just one wire and one pull-up re sistor to connect all the parts in a bus format. 3.7 pdm (pulse density modulation) pdm outputs for both corrected capaci tance and temperature are available. pdm_c (capacitance pdm) appears on the ready/pdm_c pin, and pdm_t (temperature pdm) appears on the alarm_low/pdm_t pin if enabled using the output_selection bits (see table 5.2 ). the pdm frequency is 231.25khz ? 10% (i.e., the oscillator frequency 1.85mhz ? 10% divided by 8). both pdm signals are 14-bit values. in pdm mode, the ZSSC3122 must be programmed to update mode (see section 3.3.1 ). every time a conversion cycle has finished, the pdm will begin o utputting the new value. an analog output value is created by low-pass filtering the out put; a simple first-order rc filter will work in this application. select the time constant of the filter based on the re quirements for settling time and/or peak-to-peak ripple. important: the resistor of the rc filter must be 10k ? .
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 37 of 63 table 3.12 shows some filter examples using a 10k ? resi stor. table 3.12 low pass filter example for r = 10k ? pdm_c filter capacitance (nf) vpp ripple (mv/v) 0 to 90% settling time (ms) desired analog output resolution 100 4.3 2.3 8 400 1.0 9.2 10 1600 0.3 36.8 12 6400 0.1 147.2 14 for a different (higher) resistor, the normaliz ed ripple vpp[mv/v] can be calculated as ?? ???? )nfckr( 4324 v/mvvpp ? ? ? (14 ) or the settling time t sett for a 0% to 90% settling can be calculated as ?? ? ?? nfckr0023.0mst sett ??? ? ? (15 ) ZSSC3122 provides high and low clipping limits for the pdm output. eeprom wo rds pdm_clip_high and pdm_clip_low (eeprom registers 16 hex and 17 hex ; see table 5.1 ) are the 14-bit high and low clipping limit regi sters respectively. the 14-bit values map directly to the output of the ic and can be calculated as ) 100 %_level_clip*2 (round clip_pdm 14 ? (16 ) these registers apply to both pdm_c and pdm_t. since di agnostics are reported in the pdm pin (see section 3.4 ), clipping limits allow diagnostics to be differentiated from the normal output. for detection of the diagnostic signal, a pdm_clip_high limit of 97.5% (3e66 hex ) or lower is recommended. important: the default values for the high and low clipping limits (00 hex ) are not compatible with pdm output, so the clipping limits must be changed if the pdm output is used. otherwi se, the pdm output will not work as expected. if the pdm output is not used, it is important to retain the default values of 00 hex for the clipping limits.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 38 of 63 3.8 alarm output the alarm output can be used to monitor whether a corr ected capacitance reading has exceeded or fallen below pre-programmed values. the alarm can be used to drive an open-drain load connected to vdd, as demonstrated in section 7.2 , or it can function as a full push-pull driver. if a high voltage application is required, external devices can be controlled with the alarm pins, as demonstrated in section 7.3 . the two ala rm outputs can be used at the same time, and t hese alarms can be used in combination with any of the other three modes; i 2 c, spi, or pdm. note: when both pmd_c and pdm_t are selected only alarm_high is available (see section 3.5 ). the ala rm outputs are updated when a conversion cycle is completed. the alarm outputs can be used in both update mode and sleep mode, but if sleep mode is used, i 2 c or spi must also be used to control the measure- ments (see section 3.3 ). 3.8.1 alarm registers four registers are associ ated with the alarm functions: alarm_hi gh_on, alarm_high_o ff, alarm_low_on, and alarm_low_off (see table 5.1 for eeprom addresses). each of these four regis ters is a 14-bit value that deter- mines where the alarms turn on or off. the two high al arm registers form the output with hysteresis for the alarm_high pin, and the two low alarm registers form the out put with hysteresis for the alarm_low pin. each of the two alarm pins can be configured independently using alarm_low_cfg and alarm_high_cfg located in eeprom word cust_config (see table 5.5 for bit assignments). not e: if two high alarms or two low alarms are needed, see section 3.8.4 . 3.8.2 alarm operation as shown in figure 3.14 , the alarm_high_on register determines where the high alarm trip point is and the alarm_ high_off register determines where the high alarm turns off if the high alarm has been activated. the high alarm hysteresis value is equal to alarm_high_on ? alarm_high_off. the sa me is true for the low alarm where alarm_low_on is the low alarm trip point with alarm_low_off determining the alarm shut off point. the low alarm hysteresis value is equal to alarm_low_off ? alarm_low_on. figure 3.15 shows output operation flowcharts for both the alarm_hig h and alarm_low pins.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 39 of 63 figure 3.14 example of alarm function time corrected capacitance alarm_high_on alarm_high_off alarm_low_off alarm_low_on high alarm pin on low alarm pin on low alarm pin off h y s t eresi s h y s t eresi s high alarm pin off figure 3.15 alarm outpu t flow ch art h i g h al ar m p i n no yes no measurement > alarm_high_on? measurement alarm_high_off ? alarm = off alarm = on yes low a l a r m pin no yes no measurement < alarm_low_on? measurement alarm_lo w _ off? alarm = off alarm = on yes
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 40 of 63 3.8.3 alarm output configuration the user can select the output driver configuration for each alarm using the output configuration bit in the alarm_high_cfg and alarm _low_cfg registers in eeprom word cust_config (see table 5.5 for bit assign- ments). for a pplications, such as interfacing with a microcontroller or controlling an external device (as seen in section 7.3 ), select the full push-pull driver for the alarm out put type. for an application t hat directly drives a load connected to vdd, as demonstrated in section 7.2 , the typical selection is the o pen-drain output type. an advantage of making an alarm output open drain is that in a system with multiple devices, the alarm outputs of each ZSSC3122 can be connected together with a single pul l-up resistance so that one can detect an alarm on any device with a single wire. 3.8.4 alarm polarity for both alarm pins, the polarity of the alarm output is se lected using the alarm polarity bit in the alarm_high_cfg and alarm_low_cfg registers in eeprom word cust_config (see table 5.5 for bit assignments). as shown in the example in section 7.3 , the alarms can be used to drive a high voltage humidity control system. since the humidi- fier or d ehumidifier relays must be on when the alarms are on, the alarm polarity bits are set to 0 (active high). in the example given in section 7.2 , an alarm is used to turn on an led in an open drain configuration. in order for the led to be on when the alarm is on, the output must be low, so the alarm polarity bit is set to 1 (active low). another feature of the polarity bits is the ability to creat e two high alarms or two low alarms. for example, with applications requiring two high alarms, flip the polarity bit of the alarm_low pin, and it will act as a high alarm. however, in this case, the effect of the alarm low regist ers is also changed: the alar m_low_on register would act like the alarm_high_off register and the alarm_low_off r egister would act like the alarm_high_on register. the same can be done to achieve two low alarms: the alarm_ high pin would have the polarity bit flipped, and the two alarm_high registers woul d have opposite meanings.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 41 of 63 4 command mode command mode is primarily used for calibrating the ZSSC3122. command mode is entered by sending a start_cm during the command window (see section 3.1 for more details on how to enter command mode). in comm and mode, a set of commands are available to the user to calibrate the part (see table 4.1). 4.1 command format command mode commands are only supported for the i 2 c protocol. as shown in figure 4.1 , commands are 4- byte packets with the first byte being a 7-bit slave addre ss followed by 0 for write. the second byte is the com- mand byte and the last two bytes form a 16-bit data field. figure 4.1 i 2 c command format i 2 c write , command byte, and 2 command data bytes start condition stop condition acknowledge (ack) read/write bit (example: write = 0) s 2 2 slave address bit (example: bit 2) command or data bit (example: bit 2) a s w device slave address command byte command data [15:8] command data [7:0] wait for wait for wait for wait for slave ack slave ack slave ack slave ack 6 s 5 4 2 3 1 w 0 a 6 5 7 3 4 2 0 1 a 14 13 15 11 12 10 8 9 a 6 5 7 4 2 0 1 s a 3 4.2 command encodings table 4.1 describes all the commands that are offered in command mode. not e : only the commands listed in table 4.1 are valid. other encodings might cause unp redictable results. if data is not needed for the command, zeros must be suppl ied as data to complete the 4-byte packet.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 42 of 63 table 4.1 command list and encodings command byte 8 command bits (hex) third and fourth bytes 16 data bits(hex) description response time ?? 00 h to 1f h 0000 h eeprom read of addresses 00 h to 1f h after this command has been sent and executed, a data fetch must be performed (see section 3.6.4 ). 100 s 40 h to 5f h yyyy h (y = data) write to eeprom addresses 00 h to 1f h the 2 bytes of data sent will be written to the address specified in the 6 lsbs of the command byte. 12ms 80 h 0000 h start_nom ends command mode and transitions to normal operation mode. length of initial conver- sions depends on tem- perature and capacitance resolution settings (see section 3 ). a0 h 0000 h start_cm start command mode: used to enter the command interpreting mode. start_cm is only valid during the power-on command window (see section 3.1 ). 100 s b0 h 0000 h get revision get the revision of the part. after this command has been sent and executed, a data fetch must be performed (see section 3.6.4 ). 100 s 4.3 command response and data fetch after a command has been sent and the execution time defined in table 4.1 has expired, an i 2 c data fetch (df) can be performed to fetch the response. as shown in figure 4.2 , after the slave address has been sent, the first byte fetche d is the response byte. the upper two status bits will always be 10 b to represent command mode (see section 3.4 ). the lower two bits are the response bits. table 4.2 describes the different responses that can be fet ched. to determine if a command has finished executing, poll the part until a busy re sponse is no longer received. the middle four bits of the response byte are command diagnostic bits where each bi t represents a different diagnostic (see table 4.3 ). for more information on eeprom errors see section 3.4.1 . ?? all time values shown are typical; for the worst case values, multiply by 1.1 (nominal frequency 10%).
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 43 of 63 note : regardless of what the response bits are, one or mo re of the diagnostic bits may be set indicating an error occurred during the exec ution of the command. note : only one command can be executed at a time. a fter a command is sent another command must not be sent until the execution time of the first command defined in table 4.1 has expired. for all commands except eeprom read and get revision , the data fetch should be terminated after the response byte is read. if th e command was a get revision, then the user will fetch a one byte revision as shown in figure 4.2 , example 2. the revision is coded with the upper nibb le bein g the letter corresponding to a full layer change and the lower nibble being the metal change number, for example a0. if the command was an eeprom read, then the user will fetch two more bytes as shown in figure 4.2 , example 3. if a corrected eeprom error diagnosti c was flagged after an eeprom read, the user has the option to write th is data back to attempt to fix the error. instead of polling to determine if a comm and has finished executing, the user ca n use the ready pin. in this case, wait for the ready pin to rise, which indicates that the command has executed. then a data fetch can be performed to get the response and data (see figure 4.2 ). see section 3.6.6 for more information on the ready pin.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 44 of 63 r diagnostics [5:2] status [7:6] response [1:0] diagnostics [5:2] status [7:6] response [1:0] slave address bit command or data bit status bits (example: bit 2) (example: bit 2) (in command mode always 10) (1) i 2 c df ? command status response ? 1 byte wait for slave ack master ack master nack 5 3 4 2 0 1 n s 6 5 4 2 3 1 r 0 a device slave address [6:0] 6 7 2 2 start condition stop condition acknowledge (ack) not acknowledge read/write bit (nack) (example: read = 1) s a s r n (3) i 2 c eeprom df ? command status response and eeprom data fetch ? 3 bytes 6 s 5 4 2 3 1 0 a device slave address [6:0] 6 5 7 3 4 2 0 1 a 14 13 15 11 12 eeprom data high byte [15:8] 10 a 9 8 6 5 7 3 4 2 s n 1 0 eeprom data low byte [7:0] (2) i 2 c get revision df ? command status response and clite? revision ? 2 bytes 6 s 5 4 2 3 1 r 0 a device slave address [6:0] 6 5 7 3 4 2 0 1 a 6 5 7 3 4 clite? revision data byte [7:0] 2 n 1 0 s wait for slave ack master ack master ack master nack diagnostics [5:2] status [7:6] response [1:0] s figure 4.2 command mode data fetch
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 45 of 63 table 4.2 response bits encoding name description 00 b busy the command is busy executing. 01 b positive acknowledge the command executed successfully. 10 b negative acknowledge the command was not re cognized or an eeprom write was attempted while the eeprom was locked. table 4.3 command diagnostic bits bit position name description 2 corrected eeprom error a corrected eeprom error occurred in execution of the last command. 3 uncorrectable eeprom error an uncorrectable eeprom error occurred in execution of the last command. 4 ram parity error a ram parity error occurred during a microcontroller instruction in the execut ion of the last command. 5 configuration error an eeprom or ram parity erro r occurred in the initial loading of the configuration registers.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 46 of 63 5 eeprom the eeprom array contains the calibrati on coefficients for gain and offset, etc ., and the configuration bits for the analog front end, output modes, meas urement modes, etc. the ZSSC3122 eeprom is arranged as 32 16-bit words (see table 5.1 ). the eeprom is divided into two sections. words 0 h to 15 h can only be written to if the eeprom is unlocked. after the eeprom is locked these locations can no longer be written to. the eeprom lock bits are in the zmdi_config register (see table 5.2 for the bit assignment). words 16 h to 1f h (highlighted blue in table 5.1 ) are always unlocked and available to write to at all times. see section 4 for instructions on read- ing an d writing to the eeprom in command mode via the i 2 c interface. when pr ogramming the eeprom, an internal charge pump voltage is used; therefore a high voltage supply is not needed. note: if the eeprom was accidentally locked, it can be unl ocked with the following in structions (see section 4 for how to send commands). 1. enter command mode with a start_cm command. 2. send an a2 h for the command byte and 0000 h for the command data. 3. send an f0 h for the command byte and 0021 h for the command data. 4. clear the eeprom_lock bits in the zmdi_config register with an eeprom write command. 5. reset the part. there are four customer_id words avail able for customer use, two in the lo cked region and two in the unlocked region. they can be used as a customer serial number for module traceability. (see table 5.1 for customer_id eeprom addres ses.) the integrity of the contents of the eeprom array is ensured via ecc (see section 3.4.1 ). table 5.1 provides a summary of the eeprom contents. the conf iguration register bits are explained in detail in the following subsections. table 5.1 eeprom word assignments eeprom word bit range ic default name description and notes 00 h 15:0 xxxx h cust_id0 customer id byte 0: for use by customer (default value is the upper 16 bits of the lot number) 01 h 15:0 xxxx h (llllllll b 0000ssss b ) cust_id1 customer id byte 1: for use by customer (default value is the lower 8 bits of the lot number and an 8 bit wafer number) 02 h 15:0 0b00 h zmdi_config zmdi configur ation register (see section 5.1.1 ) 03 h 15:0 0006 h not available do not change ; must leave at factory settings 04 h 15:0 00ft h not available do not change ; must leave at factory settings 05 h 15:0 0000 h not available do not change ; must leave at factory settings 06 h 15:0 0c06 h c_config afe capacitance configuration register: see table 5.3 . the t in the default setting for eeprom word 04 h represents the custom trim value determined by final test. do not change this setting.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 47 of 63 eeprom word bit range ic default name description and notes 07 h 15:0 0000 h sot_tco 2 nd order temperature offset correction for capacitance 08 h 15:0 0000 h tco temperature offset correction for capacitance 09 hh 15:0 0000 h sot_tcg 2 nd order temperature gain correction for capacitance 0a h 15:0 0000 h tcg temperature gain correction for capacitance 0b h 15:0 0000 h offset offset correction for capacitance 0c h 15:0 2000 h gain_1 gain correction for capacitance (region 1) 0d h 15:0 0000 h sot_1 2 nd order correction for capacitance (region 1) 0e h 15:0 2000 h gain_2 gain correction for capacitance (region 2) 0f h 15:0 0000 h sot_2 or tot_1 2 nd order correction for capacitance (region 2) alternatively 3 rd order correction (only one region) 10 h 15:0 7fff h raw_break break point dividing region 1 from region 2 11 h 15:0 8d92 h t_config afe temperature configuration register (see table 5.4) 12 h 15:0 0000 h offset_t offset correction for temperature 13 h 15:0 2000 h gain_t gain correction for temperature 14 h 15:0 0000 h sot_t 2 nd order correction for temperature 15 h 15:0 0000 h t ref raw temperature reading reference point 16 h 13:0 0000 h pdm_clip_high pdm high clipping limit (keep at zero unless pdm is enabled; must change default if pdm is used) 17 h 13:0 0000 h pdm_clip_low pdm low clipping limit (keep at zero unless pdm is enabled; may be changed if pdm is used) 18 h 13:0 3fff h alarm_high_on high alarm on trip point 19 h 13:0 3fff h alarm_high_off high alarm off trip point 1a h 13:0 0000 h alarm_low_on low alarm on trip point 1b h 13:0 0000 h alarm_low_off low alarm off trip point 1c h 15:0 0028 h cust_config customer configuration register (see section 5.1.4 .) 1d h 15:0 0000 h not available do not change ; must leave at factory settings 1e h 15:0 xxxx h cust_id2 customer id byte 2: for use by customer (default value is the 8 bit x and 8 bit y coordinates on the wafer) 1f h 15:0 0000 h cust_id3 customer id byte 3: for use by customer
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 48 of 63 5.1.1 zmdi configuration register (zmdi_config, eeprom word 02 hex ) this register is loaded at power-on reset and upo n exiting command mode using a start_nom command. table 5.2 zmdi_config bit assignments bit range ic default name description and notes 0 0 b measurement_mode 0 = update mode 1 = sleep mode 2:1 00 b power_down_period power down period: *** 00 b = 0ms 01 b = 5ms 10 b = 25ms 11 b = 125ms 3 0 b scale_sot_tc scales the sot tc terms: 0 = scale x 1 1 = scale x 2 4 0 b gain4x_c multiply gain_1 and gain_2 by 0 = multiply by 1 1 = multiply by 4 7:5 000 b eeprom_lock 011 b = locked all other = unlocked when eeprom is locked, the internal charge pump is disabled and the eeprom can no longer be programmed. note: if the eeprom was accidentally locked, see section 5 for instructions for unlocking it. 10:8 011 b comm_lock 011 b = locked all other = unlocked when communication is locked, i 2 c communication will only respond to its programmed address. otherwise if communication is unlocked, i 2 c will respond to any address. *** all time values shown are typical; for the worst case values, multiply by 1.1 (nominal frequency 10%).
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 49 of 63 bit range ic default name description and notes 13:11 001 b output_selection 001 b = i 2 c 011 b = spi 100 b = pdm capacitance (+ 2 alarms) 110 b = pdm capacitance + temperature (+ 1 alarm) all other configurations are not allowed see table 3.8 for more details. 14 0 b third_order 0 = piece-wise linear calibration with breakpoint 1 = third-order calibration 15 0 b not available do not change ? must leave at factory settings 5.1.2 capacitance analog front end configuration (c_config, eeprom word 06 hex ) this register is loaded immediately before a capacitanc e measurement is taken, so a power cycle is not needed for changes to take effect. table 5.3 c_config bit assignments bit range ic default name description and notes 2:0 110 b cdc_reference cdc reference capacitor selection (see table 2.1 ) 5:3 000 b cdc_offset cdc offset ca pacitor selection (see table 2.1 ) 9:6 0000 b not available do not change ? must leave at factory settings 11:10 11 b resolution cdc resolution and sample rate: ??? 00 b = 8 bits at 0.7 ms rate 01 b = 10 bits at 1.6 ms rate 10 b = 12 bits at 5.0 ms rate 11 b = 14 bits at 18.5 ms rate 13:12 00 b not available do not change ? must leave at factory settings 14 0 b differential differential input capacitance selection: 0 = single-ended 1 = differential 15 0 b not available do not change ? must leave at factory settings ??? all time values shown are typical; for the worst case values , multiply by 1.1 (nominal frequency 10%). see section 3.2 for a dditional timing factors.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 50 of 63 5.1.3 temperature analog front end configuration (t_config, eeprom word 11 hex ) this register is loaded immediately before a capacitanc e measurement is taken, so a power cycle is not needed for changes to take effect. table 5.4 t_config bit assignments bit range ic default name description and notes 2:0 010 b cdc_reference cdc reference capacitor selection. the factory settings are set for a full span temperature range from -40c to +125c. note: do not change this setting from the factory setting unless a different temperature range is needed. 5:3 010 b cdc_offset cdc offset capacitor sele ction. the factory settings are set for a full span temperature range from -40c to +125c. note: do not change this setting from the factory setting unless a different temperature range is needed. 8:6 110 b temp_trim trim setting used for the temperature measurement. the factory settings are set for a full span temperature range from -40c to +125c. note: do not change this setting from the factory setting unless a different temperature range is needed. 9 0 b not available do not change ? must leave at factory settings 11:10 11 b resolution temperature resolution and sample rate: ??? 00 b = 8 bits at 0.7 ms rate 01 b = 10 bits at 1.6 ms rate 10 b = 12 bits at 5.0 ms rate 11 b = 14 bits at 18.5 ms rate 15:12 1000 b not available do not change ? must leave at factory settings ??? all time values shown are typical; for the worst case values, multiply by 1.1 (nominal frequency 10%).
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 51 of 63 5.1.4 customer configuration register (cust_config, eeprom word 1c hex ) this register is loaded at power-on reset and upon exiting command mode after receiving a start_nom command. table 5.5 cust_config bit assignments bit range ic default name description and notes 6:0 0101000 b device_id i 2 c slave address 8:7 00 b alarm_low_cfg configure the alarm_low output pin: bits description 7 alarm polarity: 0 = active high 1 = active low 8 output configuration: 0 = full push-pull 1 = open drain 10:9 00 b alarm_high_cfg configure the alarm_high output pin: bits description 9 alarm polarity: 0 = active high 1 = active low 10 output configuration: 0 = full push-pull 1 = open drain 11 0 b spi_phase the edge of sclk t hat the master samples miso on: 0 = positive edge 1 = negative edge 12 0 b ready_open_drain ready pin is 0 = full push-pull 1 = open drain 13 0 b fast_startup sets the command window length: 0 = 10 ms command window 1 = 3 ms command window 15:14 00 b not available do not change ? must leave at factory settings
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 52 of 63 6 calibration and signal conditioning math zmdi can provide software and hardware with samples to perform the calibration. for a complete description and detailed examples, see ZSSC3122_clite_evaluation_kit_revx.x.pdf . for more details on the following equations, refer to ZSSC3122 technical note?det ailed equations for zssc312 2 clite rev c silicon math (available on request). note for best results the calibration should be done with all settings set to the final application including supply voltage, measurement mode, update rate, output mode, re solution and afe settings in the final packaging. 6.1 capacitance signal conditioning the ZSSC3122 supports up to a two-region piece-wise, non-linear sensor input or a third-order correction selectable. the general form of the capacitance signal conditioning equation is provided below. note: the following equations are only meant to show the general form and capabilities of the ZSSC3122 sensor signal conditioning. two-region piece-wise, non-linear sensor input (17) 2 2 2 1 2 1 raw*2_gain)raw*2_gain(*2_sot raw*1_gain)raw*1_gain(*1_sotout ? ? ? ? )tcg_sotttcg(t1 )tco_sotttco(t offset c_raw rawtc ???? ?? ? ? ? ? ? ? ? ? (18 ) )break_raw,rawtc(min raw 1 ? (19 ) )break_raw rawtc,0(max raw 2 ? ? (20 ) or alternatively, non-linear sensor input up to third-order correction )tcg_sotttcg(t1 )tco_sotttco(t offset c_raw raw ?????? ?????? ? ? 1 (21) (22) 1 2 1 3 1 raw*1_gain)raw*1_gain(*1_sot)raw*1_gain(*1_totout ? ? ? whe re: symbol description raw_c raw sensor reading. rawtc temperature corrected raw value. raw 1 raw value to be used for region 1 correction.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 53 of 63 symbol description raw 2 raw value used for region 2 correction. raw_break raw value at which the transition from region 1 to region 2 occurs. offset offset correction for sensor applied at 50% full scale input. gain_1 gain correction for sensor applied to region 1. sot_1 second-order correction for sensor region 1. gain_2 gain correction for sensor applied to region 2 ? not used if only 1 region is used. sot_2 alternatively tot_1 second-order correction for sensor region 2 ? not used if only 1 region is used. used as third-order term tot_1 for third-order correction. tco correction for offset drift due to temperature. tcg correction for sensitivity (gain) change due to temperature. sot_tco second-order correction for offset drift due to temperature. sot_tcg second-order correction for sensitivity change due to temperature. t ref raw temperature reading used as a reference temperature for the removal of all tc components. ? t difference between current raw temperature and the reference temperature. out corrected capacitance output value. 6.2 temperature signal compensation temperature is measured internally. temperature correctio n contains both linear gain and offset terms as well as a second-order term to correct for any nonlinearity. note: the following equation is only meant to show the general form and capabilities of the internal ZSSC3122 temperature signal conditioning. (23) t_offsett_raw*t_gain)t_raw(*t_sott ? ? ? 2 whe re: symbol range description raw_t [0,16383] raw temperature reading gain_t [-32768,32767] gain correction for internal temperature offset_t [-32768,32767] offset correction for internal temperature sot_t [-32768,32767] second-order correction for internal temperature t [-32768,32767] corrected temperature output value
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 54 of 63 6.3 limits on coefficient ranges there are range limits on some of the calibration coeffici ents that will be enforced by the calibration routine provided by zmdi. these limits ensure the integrity of the internal calculations and would only limit the most extreme cases of sensor correction. note : for alarm-only applications, it is critical that the coe fficient verification feature of the calibration routine is used since diagnostics are not reported for the alarms (see section 3.4 for more details) the table bel ow shows the limits for correction for the grade of temperature dependency and 2 nd nonlinearity of this dependency: coefficient correction condition tco 6060 ppm/k sot_tco 74 ppm/k 2 tcg 12120 ppm/k based on raw temperature values sot_tcg 147 ppm/k 2 based on raw temperature values
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 55 of 63 7 application circuit examples the ZSSC3122 provides functionality for many different c onfigurations. the following examples correspond to the example circuits shown at the beginning of the specification; however, there are many other possibilities. com- binations of these examples and many other options can gi ve the user maximum design flexibility. settings for the configuration registers are gi ven with each example. see table 5.1 for register addresses. in the examples below bits 3 and 4 of the zmdi_config register are marked with an x because they are calculated during calibration and are coefficient dependent (see section 6 ). 7.1 digital output with optional alarms in this example, a single-ended input capacitance is con- verted to the digital domain, corrected, and output via i 2 c. the configuration settings are shown in table 7.1 below. the zssc3 122 operates in sleep mode, in which meas- urement commands are used during normal operation. in this example, the i 2 c address is 28 h and the comm_lock is set. v supply (+1.8v to 5.5v) gnd 0.1f vdd vcore ready vss sda/miso scl/sclk c0 ss alarm_high cc alarm_low clite ? ZSSC3122 0.1f in this appli cation, both alarm_high and alarm_low are used for digital communication. as shown in table 7.1 below, both ala rms are configured as active high and full push-pull drivers for digital communication. the afe configuration registers select 14-bit resolution for capacitance with a capacitance range from 2.9pf to 7.2pf. the internal temperature is set to 14-bit resolution. figure 7.1 digital output with optional alarms example table 7.1 example 1: configuration settings configuration register 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 zmdi_config ( table 5.2 ) 0 ? 0 0 0 1 0 1 1 0 0 0 x x 0 0 1 cust_config ( table 5.5 ) 0 ? 0 ? 0 0 0 0 0 0 0 0 1 0 1 0 0 0 c_config ( table 5.3 ) 0 ? 0 0 0 1 1 0 ? 0 ? 0 ? 0 ? 0 1 0 0 1 1 t_config ( table 5.4 ) 1 ? 0 ? 0 ? 0 ? 1 1 0 ? 1* 1* 0* 0* 1* 0* 0* 1* 0* * the factory settings are set for a full span temperature range from -40c to +125c. do not change this setting unless a diff erent temperature range is needed. ? reserved setting ? do not change factory settings.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 56 of 63 7.2 analog output with optional alarms in this example, a single-ended input capacitance is converted, corrected and then both capacitance and temperature are output via pdm, which are then low-pass f iltered for analog outputs. one of the optional alarms controls an led. the configurat ion settings are shown below in table 7.2 . in the zmdi_config register, the output sele ction bits are set to 10 to select pdm. exam ple low-pass filter values are given in section 3.7 . for pdm, up date mode must be selected. in this appli- cation example, a 25ms power-down period has been used. in this appli cation, alarm_high is used to turn on an led in an open-drain configuration. the output must be low for the led to be on, so the alarm_high polarity bit is set to active low. the pdm clipping limits are set for 10% (666 hex ) to 90% (3999 hex ) output. the afe configuration registers show a resolution of 14 bits for capacitance; however, the pdm low pass filter may be set for a lower resolution with a faster settling time (see section 3.7 ). a capacitance range of 1.4pf to 8.6pf h as been chosen. the internal temperature is set to 12-bit resolution. figure 7.2 analog output with optional alarms example table 7.2 example 2: configuration settings configuration register 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 zmdi_config ( table 5.2 ) 0 ? 0 1 1 0 0 1 1 0 0 0 x x 1 0 0 cust_config ( table 5.5 ) 0 ? 0 ? 0 0 0 0 1 0 0 0 1 0 1 0 0 0 c_config ( table 5.3 ) 0 ? 0 0 0 1 1 0 ? 0 ? 0 ? 0 ? 0 0 1 1 0 1 t_config ( table 5.4 ) 1 ? 0 ? 0 ? 0 ? 1 0 0 ? 1* 1* 0* 0* 1* 0* 0* 1* 0* pdm_clip_high 0 0 1 1 1 0 0 1 1 0 0 1 1 0 0 1 pdm_clip_low 0 0 0 0 0 1 1 0 0 1 1 0 0 1 1 0 * the factory settings are set for a full span temperature range from -40c to +125c. do not change this setting unless a diff erent temperature range is needed. ? reserved setting ? do not change factory settings.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 57 of 63 7.3 bang-bang control system in this example, the only outputs are the alarm pins. they are programmed to control a high voltage bang-bang hu- midity control system. exter nal devices are not needed if not using high voltage. if the humidity gets too high, the ZSSC3122 activates the dehumidifier using the alarm_high pin. if the humidity gets too low, it activates the humidifier with the alarm_low pin. the alarm registers must be set to appropriate trip and hysteresis points (see section 3.8 ). the co nfiguration settings are shown in table 7.3 . the outp ut selection bits should either be set to i 2 c or spi since depending on the pdm configuration, both alarms are not supported. additionally, i 2 c and spi are lower power than pdm. this application does not use i 2 c or spi, so update mode must be used because sleep mode commands cannot be sent. the fastest update rate is used for this example. external devices are needed to control the outputs because a voltage source greater than vdd is used. figure 7.3 bang-bang co ntrol system example the alarm pins control nmos devices so the alarm pins must be full push-pull and output high when the alarm is on, so the polarity bits are set to 0 and the open drain bits are set to 0. in this example application, a faster response time ma y be needed, so the afe configuration settings show 10-bit resolution for both capacitance and internal temperatur e. c_config settings have been selected for a capacitance range of 5.8pf to 7.2pf (see table 2.1 ). table 7.3 example 3: configuration settings configuration register 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 zmdi_config ( table 5.2 ) 0 ? 0 0 0 1 0 1 1 0 0 0 x x 0 0 0 cust_config ( table 5.5 ) 0 ? 0 ? 0 0 0 0 0 0 0 0 1 0 1 0 0 0 c_config ( table 5.3 ) 0 ? 0 0 0 0 1 0 ? 0 ? 0 ? 0 ? 1 0 0 0 0 1 t_config ( table 5.4 ) 1 ? 0 ? 0 ? 0 ? 0 1 0 ? 1* 1* 0* 0* 1* 0* 0* 1* 0* * the factory settings are set for a full span temperature range from -40c to +125c. do not change this setting unless a diff erent temperature range is needed. ? reserved setting ? do not change factory settings. dehumidifier gnd gnd 0.1f v supply +1.8v to 5.5v humidifier gnd 12v 12v vdd vcore vss alarm_high c0 alarm_low cc clite ? ZSSC3122 0.1f
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 58 of 63 7.4 differential input capacitance this example shows that the full functionality of the zssc 3122 including the applications illustrated in examples 1, 2, and 3, can be implemented with a differential input capacitance. the capacitor c cc allows a non-galvanic con- nection (e.g., to the moving part of a motion sensor as pa rt of the sensor construction), but it is not needed for sensor types with existing galvanic connections. the configuration settings are shown in table 7.4 . the differenti al bit is set to select differential input capacitance. in this example, spi has been selected in update mode at the fastest update rate. the spi phase is set to 1 so that the master samples miso on the negative edge of sclk. the eeprom has been locked. the afe co nfiguration registers select 14-bit reso- lution for capacitance and 10-bit resolution for internal temperature. because this is the differential config- uration, both the internal reference and offset capaci- tors are set to zero. figure 7.4 differential input capacitance example table 7.4 example 4: configuration settings configuration register 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 zmdi_config ( table 5.2 ) 0 ? 0 0 1 1 0 0 0 0 1 1 x x 0 0 0 cust_config ( table 5.5 ) 0 ? 0 ? 0 0 1 0 0 0 0 0 1 0 1 0 0 0 c_config ( table 5.3 ) 0 ? 1 0 0 1 1 0 ? 0 ? 0 ? 0 ? 0 0 0 0 0 0 t_config ( table 5.4 ) 1 ? 0 ? 0 ? 0 ? 0 1 0 ? 1* 1* 0* 0* 1* 0* 0* 1* 0* * the factory settings are set for a full span temperature range from -40c to +125c. do not change this setting unless a diff erent temperature range is needed. ? reserved setting ? do not change factory settings.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 59 of 63 7.5 external reference capacitor this example demonstrates that the full functionality of the ZSSC3122, including the applications illu strated in examples 1, 2, and 3, can be implemented with an exter- nal reference capacitor in conjunction with a single-ended input capacitance. in this example, the digital output is used. the external reference is used. the configuration settings are shown in table 7.5 . example co nfiguration settings show i 2 c in sleep mode with the comm_lock off so that the ZSSC3122 can res- pond to any i 2 c slave address. also the ready pin is configured for open drain so that multiple devices can have their ready lines connected together. the afe configuration registers select 12-bit resolution for capacitance and 12-bit resolution for internal temper- ature. this example also s hows an offset setting of 4.3pf. figure 7.5 ext. reference input capacitance example table 7.5 example 5: configuration settings configuration register 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 zmdi_config ( table 5.2 ) 0 ? 0 0 0 1 0 0 0 0 0 0 x x 0 0 0 cust_config ( table 5.5 ) 0 ? 0 ? 0 1 0 0 0 0 0 0 1 0 1 0 0 0 c_config ( table 5.3 ) 0 ? 0 0 0 1 0 0 ? 0 ? 0 ? 0 ? 0 1 1 0 0 0 t_config ( table 5.4 ) 1 ? 0 ? 0 ? 0 ? 1 0 0 ? 1* 1* 0* 0* 1* 0* 0* 1* 0* * the factory settings are set for a full span temperature range from -40c to +125c. do not change this setting unless a diff erent temperature range is needed. ? reserved setting ? do not change factory settings. 8 esd/latch-up-protection all external module pins have an esd protecti on of >4000v and a latch-up protection of ? 100ma or (up to +8v / down to ?4v) relative to vss/vssa. the internal module pin vcore has an esd prot ection of > 2000v. esd protection referenced to the human body model is te sted with devices in tssop14 packages during product qualification. the esd test follows the human body model with 1.5kohm/100pf based on mil 883, method 3015.7.
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 60 of 63 9 pin configuration and package the standard package for the ZSSC3122 is a tssop-14 (4.40.1mm body wide) with lead-pitch 0.65mm. see the notes in table 9.2 regarding connection requirements. table 9.1 storage and soldering condition storage and soldering tssop14 ? maximum storage temperature t max _ storage less than 10hrs, before mounting ?? 150? ?c ? minimum storage temperature: t min _ storage at original packing only -55 ? ?? ?c ? maximum drybake temperature t drybake ? less than100hrs in summary, before mounting ?? 125? ?c ? soldering peak temperature t peak ? less than 30s (ipc/jedec-std-020 standard) ?? 260? ?c ? figure 9.1 ZSSC3122 pin-out diagram table 9.2 ZSSC3122 pin assignments for tssop-14 pin name description notes 1 vcore core voltage always connect to an external capacitor to gnd that is within the specifications given in section 1.3 for c vcore_sm and c vcore_um . this is the only internal module pin. refer to section 8 for esd details. 2 c0 capacitor input 0 3 vss ground supply connecting to gnd for shielding is strongly recommended. 4 cc common capacitor input 1 14 2 13 3 12 4 11 5 10 6 9 7 8
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 61 of 63 pin name description notes 5 vss ground supply connecting to gnd for shielding is strongly recommended. 6 c1 capacitor input 1 if not used, must be unconnected. 7 vdd supply voltage (1.8v to 5.5v) must connect to vsupply. 8 alarm_low/ pdm_t low alarm output temperature pdm (see table 3.8 ) if not used, must be un connected. 9 alarm_high high alarm output if not used, must be unconnected. 10 ready/ pdm_c ready signal (conversion complete output) capacitance pdm (see table 3.8 ) if not used, must be un connected. 11 vss ground supply must connect to gnd. 12 sda/miso i 2 c data if in i 2 c mode master-in-slave-out if in spi mode (see table 3.8 ) if not used, must co nnect to vdd. 13 scl/sclk i 2 c clock if in i 2 c mode serial clock if in spi mode (see table 3.8 ) if not used, must co nnect to vdd. 14 ss slave select (input) if in spi mode (see table 3.8 ) if not used, must be un connected. 10 test the test program is based on this datasheet. the final parameters, which will be tested during production, are listed in the tables and graphs of section 1 .
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 62 of 63 11 reliability a reliability investigation according to the in -house non-automotive standard will be performed. 12 customization for high-volume applications that require an upgraded or downgraded functionality compared to the ZSSC3122, zmdi can customize the circuit design by adding or removing certain functional blocks. for this customization, zmdi has a considerable library of sensor-dedicat ed circuitry blocks, which enable zmdi to provide a custom solution quickly. pleas e contact zmdi for further information. 13 part ordering codes please contact zmdi sales for additional options. sales code description package ZSSC3122aa1b ZSSC3122 clite? die ? temperature range: -40c to +125c tested dice on un-sawn wafer ZSSC3122aa1c ZSSC3122 clite? die ? temperature range: -40c to +125c tested dice on frame ZSSC3122aa2 ZSSC3122 clite? tssop14 ? temperature range: -40c to +125c ? lead-free package tube: add ?t? to sales code reel: add ?r? ZSSC3122kit ZSSC3122 ssc evaluation kit: comm unication board, ssc evaluation board, sensor replacement board, evaluation software, usb cable, 5 ic samples kit contact z mdi sales for support and sales of the ZSSC3122 mass calibration system. 14 related documents document file name ZSSC3122 clite? evaluation kit description ZSSC3122_clite_evaluation_kit_revx.x.pdf visit zmdi?s website www.zmdi.com or contact your nearest sales office for the latest version of these documents. 15 glossary term description adc analog-to-digital converter cdc capacitance-to-digital converter dac digital-to-analog converter ecc error checking and correction ssc sensor signal conditioner
ZSSC3122 clite? low voltage capacitive sensor signal conditioner data sheet august 16, 2011 ? 2011 zentrum mikroelektronik dresden ag ? rev.1.20 all rights reserved. the material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. the information furnished in this publication is subject to changes without notice. 63 of 63 16 document revision history revision date description 1.00 15-feb11 first release. 1.10 29-jun-11 added specificati on for ?excitation frequency of external capacitances c 0 and c 1 ? in section 1.3 and 2.2.1 . adde d ?pdm frequency? specification to table in section 1.3 . in section 3.7 , clarified that clipp ing limit default values must be adjusted for pdm output functionality. revised pdm frequency in sections 1.3 and 3.7 . revised pdm ripple and settling time specific ations in section 1.3 . revised related examples in table 3.12 and corrected e quation (14) for calculating ripple. revisions to text explaining equation (16) and subsequent text recommending limits for pdm_clip_high. revised table 5.1 for pdm_clip_high and pdm_clip_low. added new settings for pdm clipping limits to sectio n 7.2 and revised related settings in table 7.2 . revised section 1.6 for addition of specifications for ?volta ge dependency? for the temperature channel to section 1.3 . revised section 2.2.1.3 regarding total capacitance. revised def ault value for eeprom word 04 h from 007t h to 00ft h in table 5.1 . minor edits for clarit y in section 7.3 . revise d notes for vcore pin 1 in table 9.2 . revisions to section 3.3.2.1 . 1.20 16-aug-2011 added spec ifications in section 1.3 for v por maximum, v reg typical and maximum, and psr temp. revisions to section 3.3.2.1 to explain preferred method for detecting valid data. revise d product ordering codes. sales and further information www.zmdi.com ssc@zmdi.com zentrum mikroelektronik dresden ag (zmd ag) grenzstrasse 28 01109 dresden germany zmd america, inc. 8413 excelsior drive suite 200 madison, wi 53717 usa zentrum mikroelektronik dresden ag, japan office 2nd floor, shinbashi tokyu bldg. 4-21-3, shinbashi, minato-ku tokyo, 105-0004 japan zmd far east, ltd. 3f, no. 51, sec. 2, keelung road 11052 taipei taiwan phone +49 (0)351.8822.7.772 fax +49 (0)351.8822.87.772 phone +1 (608) 829-1987 fax +1 (631) 549-2882 phone +81.3.6895.7410 fax +81.3.6895.7301 phone +886.2.2377.8189 fax +886.2.2377.8199 disclaimer : this information applies to a product under development. its characteristics and specifications are subject to change without notice. zentrum mikroelektronik dresden ag (zmd ag) assumes no obligation regarding future manufacture unless otherwise agreed to in writing. the information furnished hereby is believed to be true and accurate. however, under no circumstances shall zmd ag be liable to any customer, licensee, or any other third party for any special, indirect, incident al, or consequential damages of any kind or nature whatsoever arising out of or in any way related to the furnishing, performance, or use of this technical data. zmd ag hereby expressly dis claims any liability of zmd ag to any customer, licensee or any other third party, and any such customer, licensee and any other third party hereby waives any liability of zmd ag for any dama ges in connection with or arising out of the furnishing, performance or use of this technical data, whether based on contract, warranty, tort (including negligence), strict liability, or otherwise.
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