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rev. 1.0 8/15 copyright ? 2015 by silicon laboratories SI7034-A10 SI7034-A10 d igital i 2 c h umidity and t emperature s ensor features applications description the si7034 i 2 c humidity and temperature sensor is a monolithic cmos ic integrating humidity and temperature sensor elements, an analog-to-digital converter, signal processing, calibration data, and an i 2 c interface. the patented use of industry-standard low-k polymeric dielectrics for sensing humidity enables the construction of low-power, monolithi c cmos sensor ics with low drift and hysteresis, and excellent long-term stability. the humidity and temperature sensors ar e factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. this ensures that the sensors are fully interchangeable, with no cali bration or software changes required. the si7034 is available in a 2x2 mm dfn package and is reflow solderable. it can be used as a hardware- and software-com patible drop-in upgrade for existing rh/ temperature sensors in 2x2 mm qfn-6 packages. the si7034 offers an accurate, low-power, factory-calibrated digital solu tion ideal for measuring humidity, dew point, and temperature in applications ranging from hvac/r and asset tracking to industrial and consumer platforms. ? precision relative humidity sensor ?? 4% rh (max), 0?80% rh ? high accuracy temperature sensor ?? 0.4 c (max), ?10 to 85 c ? 0 to 100% rh operating range ? ?40 to +125 c operating range ? low voltage operation ? low power consumption ?? 50 na, standby current ? factory-calibrated ? i 2 c interface ? integrated on-chip heater ? 2x2 mm qfn package ? excellent long term stability ? mobile smartphones and tablets ? consumer electronics ? hvac/r ? respiratory therapy ? white goods ? asset and goods tracking ? thermostats/humidistats ? micro-environments/data centers ? indoor weather stations patent protected. patents pending ordering information: see page 23. pin assignments top view dnc scl vdd 1 2 3 5 4 gnd sda dnc 6
SI7034-A10 2 rev. 1.0 functional block diagram adc gnd humidity sensor control logic scl si7034 temp sensor 1.25v ref i 2 c interface sda vdd calibration memory
SI7034-A10 rev. 1.0 3 t able of c ontents section page 1. electrical specificat ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2. typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3. bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4. functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 4.1. relative humidity sens or accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2. hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 4.3. prolonged exposure to high humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 4.4. pcb assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5. protecting the sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.6. bake/hydrate procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.7. long term drift/aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5. i2c interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 5.1. issuing a measurement command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.2. reading and writing user registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.3. measuring relative humidi ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.4. measuring temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.5. firmware revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.6. electronic serial number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 5.7. heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6. control registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 7. pin descriptions: si7034 (top view) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 8. ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 9. package outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 9.1. package outline: 2x2 6- pin qfn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 10. pcb land pattern and solder mask d esign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 11. top marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26 11.1. si7034 top marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 11.2. top marking explana tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 12. additional reference resour ces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 document change list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 contact information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
SI7034-A10 4 rev. 1.0 1. electrical specifications unless otherwise specified, all mi n/max specifications apply over the recommended operating conditions. table 1. recommended operating conditions parameter symbol test condition min typ max unit power supply v dd 1.67 ? 1.98 v operating temperature t a ?40 ? +125 c table 2. general specifications 1.67 v dd 1.98 v; t a = ?40 to +125 c unless otherwise noted. parameter symbol test condition min typ max unit input voltage high v ih scl, sda pins 0.7xvdd ? ? v input voltage low vil scl, sda pins ? ? 0.3xvdd v input voltage range vin scl, sda pins with respect to gnd 0.0 ? vdd+2 v input leakage iil scl, sda pins ? ? 1 a output voltage low vol sda pin; iol = 1.5 ma ? ? 0.4 v current consumption i dd normal mode, temperature conversion in progress 1 ? 245 288 a normal mode, rh conversion in progress 1 ? 106 145 a fast mode, parallel temperature and rh conversion in progress 2 ? 337 398 a fast mode, rh conversion in progress 3 ? 106 145 a standby, ?40 to +85 c 5 ? 0.05 0.56 a standby, ?40 to +125 c 5 ? 0.05 5.2 a peak idd during powerup 6 ?45.1 ma peak idd during i 2 c operations 7 ?3.5 4 ma after writing to user registers 8 ? 11.6 17 a heater current 9 i heat ? 6.4 to 53.5 ? ma notes: 1. in normal mode, a temperature conversion is performed first, followed by an rh conversion. 2. in fast mode, both a temperature conver sion and an rh conversion are initiated at the same time and occur in parallel. 3. current consumption of rh conversion af ter the temperature conversion has fini shed. in fast mode, the temperature conversion finishes before the rh conversion. 4. additional time for rh conversion after the temperature conversion has finished. 5. no conversion or i 2 c transaction in progress. typical values measured at 25 c. 6. occurs once during powerup. duration is <5 msec. 7. occurs during i 2 c commands for reset, read/write user registers, read eid, and read firmware version. duration is <100 s when i 2 c clock speed is >100 khz (>200 khz for 2-byte commands). 8. idd after a user register write. initiating any other subsequent i 2 c transaction on the same bus (such as a user register read, starting an rh measurement, or traffic directed at other i 2 c devices) will transition the device to standby mode. 9. additional current consumption when htre bit enabled.
SI7034-A10 rev. 1.0 5 conversion time t conv normal mode, rh conversion 1 5.8 8.5 ms normal mode, temperature conversion 1 3.7 6 ms fast mode, parallel temp and rh conver- sion 2 0.9 1.5 ms fast mode, additional rh conversion time 4 1.6 2.5 ms powerup time t pu from vdd 1.67 v to ready for a conversion, 25 c ? 10 15 ms from vdd 1.67 v to ready for a conversion, full temperature range ? ?50 ms after issuing a software reset command ?1.22.0 ms table 3. i 2 c interface specifications 1 1.67 v dd 1.98 v; t a = ?40 to +125 c unless otherwise noted. parameter symbol test condition min typ max unit hysteresis v hys high-to-low versus low-to-high transition 0.05 x v dd ??v sclk frequency 2 f scl ? ? 400 khz scl high time t skh 0.6 ? ? s scl low time t skl 1.3 ? ? s start hold time t sth 0.6 ? ? s notes: 1. all values are referenced to v il and/or v ih . 2. depending on the conversion command, the si7034 may hold t he master during the conversion (clock stretch). at above 300 khz scl, the si7034 may hold the master briefly fo r user register and device id transactions. at the highest i 2 c speed of 400 khz the stretching will be <50 s. 3. pulses up to and including 50 ns will be suppressed. table 2. general specifications (continued) 1.67 v dd 1.98 v; t a = ?40 to +125 c unless otherwise noted. parameter symbol test condition min typ max unit notes: 1. in normal mode, a temperature conversion is performed first, followed by an rh conversion. 2. in fast mode, both a temperature conver sion and an rh conversion are initiated at the same time and occur in parallel. 3. current consumption of rh conversion af ter the temperature conversion has fini shed. in fast mode, the temperature conversion finishes before the rh conversion. 4. additional time for rh conversion after the temperature conversion has finished. 5. no conversion or i 2 c transaction in progress. typical values measured at 25 c. 6. occurs once during powerup. duration is <5 msec. 7. occurs during i 2 c commands for reset, read/write user registers, read eid, and read firmware version. duration is <100 s when i 2 c clock speed is >100 khz (>200 khz for 2-byte commands). 8. idd after a user register write. initiating any other subsequent i 2 c transaction on the same bus (such as a user register read, starting an rh measurement, or traffic directed at other i 2 c devices) will transition the device to standby mode. 9. additional current consumption when htre bit enabled.
SI7034-A10 6 rev. 1.0 figure 1. i 2 c interface timing diagram start setup time t sts 0.6 ? ? s stop setup time t sps 0.6 ? ? s bus free time t buf between stop and start 1.3 ? ? s sda setup time t ds 100 ? ? ns sda hold time t dh 100 ? ? ns sda valid time t vd;dat from scl low to data valid ? ? 0.9 s sda acknowledge valid time t vd;ack from scl low to data valid ? ? 0.9 s suppressed pulse width 3 t sp 50 ? ? ns table 3. i 2 c interface specifications 1 (continued) 1.67 v dd 1.98 v; t a = ?40 to +125 c unless otherwise noted. parameter symbol test condition min typ max unit notes: 1. all values are referenced to v il and/or v ih . 2. depending on the conversion command, the si7034 may hold t he master during the conversion (clock stretch). at above 300 khz scl, the si7034 may hold the master briefly fo r user register and device id transactions. at the highest i 2 c speed of 400 khz the stretching will be <50 s. 3. pulses up to and including 50 ns will be suppressed. scl d7 1/f scl t skh sda t skl t sth d6 d5 d0 r/w ack t ds t dh start bit stop bit t buf t sts t vd : ack t sps t sp
SI7034-A10 rev. 1.0 7 figure 2. rh accuracy at 30 c table 4. humidity sensor 1.67 v dd 1.98 v; t a = 30 c unless otherwise noted. parameter symbol test condition min typ max unit operating range 1 non-condensing 0 ? 100 %rh accuracy 2, 3 0 ? 80% rh ? 3 +4 %rh 80 ? 100% rh see figure 2 repeatability/noise 4 normal ? 0.15 ? %rh rms fast ? 0.45 ? response time 5 63% 1m/s airflow ? 18 ? s drift vs. temperature ? 0.05 ? %rh/c hysteresis ? 1 ? %rh long term stability 3 ? 0.25 ? %rh/yr notes: 1. recommended humidity operating range is 20% to 80% rh (non-condensing) over ?10 c to 60 c. prolonged operation beyond these ranges may result in a shift of sensor reading, with slow recovery time. 2. excludes hysteresis, long term drift, and certain other fact ors and is applicable to non-condensing environments only. see relative humidity sensor accuracy for more details. 3. drift due to aging effects at typical room conditions of 30 c and 30% to 50% rh. may be impacted by dust, vaporized solvents or other contaminants, e.g., out-gassing tapes, a dhesives, packaging materials, etc. see section ?4.7. long term drift/aging?. 4. 3-sigma measurement deviation. 5. response time to a step change in rh. time for the rh output to change by 63% of the total rh change.
SI7034-A10 8 rev. 1.0 figure 3. temperature accuracy table 5. temperature sensor 1.67 v dd 1.98 v; t a = ?40 to +125 c unless otherwise noted. parameter symbol test condition min typ max unit operating range ?40 ? +125 c accuracy 1 t a =30 c ? 0.3 0.4 c ?40 < t a < 125c figure3 repeatability/noise 2 normal ? 0.03 ? c rms fast ? 0.09 ? response time 3 63% unmounted device ? 0.7 ? s si7034-eb ? 5.1 ? long term stability ? < 0.01 ? c/yr notes: 1. normal conversion time. 2. 3-sigma measurement deviation. 3. time to reach 63% of final value in response to a step change in temperature. actual response time will vary dependent on system thermal mass and air-flow.
SI7034-A10 rev. 1.0 9 table 6. thermal characteristics parameter symbol test condition qfn-6 unit junction to air thermal resistance ja jedec 2-layer board, no airflow 173 c/w junction to air thermal resistance ja jedec 2-layer board, 1 m/s airflow 153 c/w junction to air thermal resistance ja jedec 2-layer board, 2 m/s airflow 146 c/w junction to case thermal resistance jc jedec 2-layer board 84 c/w junction to board thermal resistance jb jedec 2-layer board 114 c/w table 7. absolute maximum ratings 1,2 parameter symbol test condition min typ max unit ambient temperature under bias ?55 ? 125 c storage temperature ?65 ? 150 c voltage on i/o pins ?0.3 ? vdd+2.0 v v voltage on vdd with respect to gnd ?0.3 ? 2.3 v esd tolerance hbm 2 kv cdm 1.25 kv mm 250 v notes: 1. absolute maximum ratings are stress ratings only, operation at or beyond these conditio ns is not implied and may shorten the life of the device or alter its performance. 2. special handling considerations apply; see application note, ?an607: si70xx humidity and temperature sensor designer?s guide?.
SI7034-A10 10 rev. 1.0 2. typical application circuit the primary function of the si7034 is to measure relati ve humidity and temperature. figure 4 demonstrates the typical application circuit to achieve these functions; pi ns 3 and 6 are not required and must be left unconnected. do not connect pins 3 and 6 to ground or pull up to vdd. they should be soldered to floating pads for mechanical stability of the package. figure 4. typical application circuit for relative humidity and temperature measurement 1. to 1. v scl sda si7034 vdd 1 scl 2 dnc 3 dnc 6 sda 4 gnd 5 c1 0.1uf r2 10k r1 10k
SI7034-A10 rev. 1.0 11 3. bill of materials table 8. typical application circuit bom for relative humidity and temperature measurement reference description mfr part number manufacturer r1 resistor, 10 k , 5%, 1/16w, 0402 cr0402-16w-103jt venkel r2 resistor, 10 k , 5%, 1/16w, 0402 cr0402-16w-103jt venkel c1 capacitor, 0.1 f, 6.3 v, x7r, 0402 c0402x7r6r3-104mnp venkel u1 ic, digital temperat ure/humidity sensor si 7034-a10-im silicon labs
SI7034-A10 12 rev. 1.0 4. functional description figure 5. si7034 block diagram the si7034 is a digital relative humidity and temperature sensor that integrates temp erature and humidity sensor elements, an analog-to-digital converter, signal processing , calibration, polynomial non-linearity correction, and an i 2 c interface all in a single chip. the si7034 is individually factory-calibra ted for both temperature and humidity, with the calibration data stored in on-chip non-volat ile memory. this ensures that the sensor is fully interchangeable, with no recalibration or changes to soft ware required. patented use of industry-standard cmos low-k dielectrics as a sensor enable s the si7034 to achiev e excellent long term stability and immunity to contaminants with low drift and hysteresis. the si7034 of fers a low power, high accuracy, calibrated and stable solution ideal for a wide range of temperature, humi dity, and dew-point applications including medical and instrumentation, high reliab ility automotive and industri al systems, and cost-sensi tive consumer electronics. while the si7034 is largely a conventional mixed-signal cmos integrated circuit, relative humidity sensors in general and those based on capacitive sensing using polymeric dielectric have unique application and use requirements that are not common to conventional (non-sensor) ics. chief among those are as follows: ?? the need to protect the sensor during board assembly, i.e., solder reflow, and the need to subsequently rehydrate the sensor. ?? the need to protect the sensor from damage or contamination during the product life-cycle. ?? the impact of prolonged exposure to extremes of temper ature and/or humidity and their potential effect on sensor accuracy. ?? the effects of humidity sensor ?memory?. each of these items is discussed in more detail in the following sections. adc gnd humidity sensor control logic scl si7034 temp sensor 1.25v ref i 2 c interface sda vdd calibration memory
SI7034-A10 rev. 1.0 13 4.1. relative humidi ty sensor accuracy to determine the accuracy of a relative humidity sensor, it is placed in a temperat ure and humidity controlled chamber. the temperature is set to a convenient fixed valu e (typically 25?30 c) and the relative humidity is swept from 20 to 80% and back to 20% in the following steps: 20% ? 40% ? 60% ? 80% ? 80% ? 60% ? 40% ? 20%. at each set-point, the chamber is allowed to settle for a pe riod of 30 minutes before a reading is taken from the sensor. prior to the sweep, the devic e is allowed to stabilize to 50%rh. the solid trace in figure 6, ?measuring sensor accuracy including hysteresis,? shows the result of a typical sweep. figure 6. measuring sensor accuracy including hysteresis the rh accuracy is defined as the dott ed line shown in figure 6, which is th e average of the two data points at each relative humidity set-point. in this case, the sensor shows an accuracy of 0.25%rh. the si7034 accuracy specification (table 4) includes: ?? unit-to-unit and lot-to-lot vari ation in non-linearity compensation ?? accuracy of factory calibration ?? margin for shifts that can occur during ir solder reflow (compensation for shift due to reflow is included in the linearization procedure below) the accuracy specification does not include: ?? hysteresis (typically 1%). ?? effects from long term exposure to very humid conditions ?? contamination of the sensor by particulates, chemicals, etc. ?? other aging related shifts (?long-term stability?) ?? variations due to tem perature. rh readings will typica lly vary with temperature by < + 0.05% / c.
SI7034-A10 14 rev. 1.0 4.2. hysteresis the moisture absorbent film (polymeric dielectric) of the humidity sensor will carry a memory of its exposure history, particularly its recent or ex treme exposure history. a sensor exposed to relative ly low humidity will carry a negative offset relative to the fact ory calibration, and a sensor exposed to relatively high humidity will carry a positive offset relative to th e factory calibration. this fact or causes a hysteresis effect illustrated by the solid trace in figure 5. the hysteresis value is the difference in %rh between the maximum absolute error on the decreasing humidity ramp and the maximum absolute error on the in creasing humidity ramp at a single relative humidity setpoint and is expressed as a bipolar quantity relative to the average error (dashed trace). in the example of figure 5, the measurement uncertainty due to the hysteresis effect is +/-1.0%rh. 4.3. prolonged expos ure to high humidity prolonged exposure to high humidity will result in a gra dual upward drift of the rh reading. the shift in sensor reading resultin g from this drift will generally disappear slowly unde r normal ambient cond itions. the amount of shift is proportional to the magnitude of relative humidi ty and the length of exposure. in the case of lengthy exposure to high humidity, some of the resulting shift may persist indefinitely under typical conditions. it is generally possible to substantially re verse this affect by baking the device (see section ?4.6. bake/hydrate procedure? ). 4.4. pcb assembly 4.4.1. soldering like most ics, si7034 devices are shipped from the fa ctory vacuum-packed with an enclosed desiccant to avoid any rh accuracy drift during storage and to prevent any moisture-related issues during solder reflow. the following guidelines should be observed during pcb assembly: ?? si7034 devices are compatible with standard board as sembly process. devices should be soldered using reflow per the recommended card reflow profile. see section ?10. pcb land pattern and solder mask design? for the recommended card reflow profile. ?? a ?no clean? solder process is recommended to minimize the need for water or solvent rinses after soldering. cleaning after soldering is possible, bu t must be done carefully to avoid impacting the performance of the sensor. see an607 for more information on cleaning. ?? it is essential that the exposed polymer sensing film be kept clean and undamaged. this can be accomplished by careful handling and a clean, well-c ontrolled assembly process. when in doubt or for extra protection, a heat-re sistant, protective cover such as k apton(r) kppd-1/8 poly imide tape can be installed during pcb assembly. 4.4.2. rehydration the measured humidity value w ill generally shift slightly after solder refl ow. a portion of this shift is permanent and is accounted for in the accuracy specifications in tabl e 4. after soldering, an si7034 should be allowed to equilibrate under contro lled rh conditions (room temperature, 45?55 %rh) for at least 48 hours to eliminate the remainder of the shift and return the devi ce to its specified accuracy performance. 4.4.3. rework to maintain the specified sensor performance, care must be taken during rework to minimize the exposure of the device to excessive heat and to avoid damage/contaminati on or a shift in the sensor reading due to liquids, solder flux, etc. manual touch-up using a soldering ir on is permissible under the following guidelines: ?? the exposed polymer sensing film must be kept clean and undamaged. a kapton ? tape protective cover is recommended during any rework operation. ?? flux must not be allowed to contaminate the sensor; liquid flux is not recommended even with a cover in place. conventional lead-free solder with rosin core is acceptable for touch-up as long as a cover is in place during the rework. ?? if possible, avoid water or solvent rinses after touch- up. cleaning after soldering is possible, but must be done carefully to avoid impacting the performance of the sensor. see an607 for more information on cleaning.
SI7034-A10 rev. 1.0 15 ?? minimize the heating of the device. soldering iron temperatures should not e xceed 350 c and that the contact time per pin should not exceed 5 seconds. ?? hot air rework is not recommended. if a device must be replaced, remove the device by hot air and solder a new part in its place by reflow following the guidelines above. *note: all trademarks are the property of their respective owners. 4.5. protecting the sensor because the sensor operates on the pr incipal of measuring a change in capa citance, any changes to the dielectric constant of the polymer film will be detect ed as a change in relative humidity. therefore, it is important to minimize the probability of contaminants coming into contact with the sensor. dust and ot her particles as well as liquids can affect the rh reading. depending on the needs of the app lication, there may be a need for basic protection against particulates or something more sophisticated such as a hydrophobic membrane providing up to ip67 compliant protection, during pcb assembly and/or the end system. 4.6. bake/hydrate procedure after exposure to extremes of temperature and/or humi dity for prolonged periods, the polymer sensor film can become either very dry or very wet, in each case the result is either high or low relative humidity readings. under normal operating conditions, the induced error will diminish over time. from a very dry condition, such as after shipment and soldering, the error will diminish over a few days at ty pical controlled ambient conditions, e.g., 48 hours of 45 %rh 55. however, from a very wet condition, recovery may take signi ficantly longer. to accelerate recovery from a wet condition, a bak e and hydrate cycle can be implemente d. this operation consists of the following steps: ?? baking the sensor at 125 c for 12 hours ?? hydration at 30 c in 75% rh for 10 hours following this cycle, the sensor will return to normal o peration in typical ambient conditions after a few days. 4.7. long term drift/aging over long periods of time, the sensor readings may dr ift due to aging of the devic e. standard accelerated life testing of the si7034 has resulted in the specifications for long-term drift shown in table 4 and table 5. this contribution to the overall sensor accuracy accounts only for the long-term aging of the device in an otherwise benign operating environment and does not include the effe cts of damage, contamination, or exposure to extreme environmental conditions.
SI7034-A10 16 rev. 1.0 5. i 2 c interface the si7034 communicates with the host controller over a digital i 2 c interface. the 7-bit base slave address is 0x70. master i 2 c devices communicate with the si7034 using a co mmand structure. the commands are listed in the i 2 c command table. commands other than those documented below are undefined and should not be sent to the device. table 9. i 2 c slave address byte a6 a5 a4 a3 a2 a1 a0 r/w 11100001/0 table 10. i 2 c command table command hold/no hold mode hex code read electronic id: two separate ids with checksum ? 0xfa 0x0f read electronic id: two separate ids with checksum ? 0xfc 0xc9 soft reset ? 0xfe temperature and relative humidity measurement: normal mode hold mode 0x7c 0xa2 temperature and relative humidity measurement: normal mode no hold mode 0x78 0x66 temperature and relative humidity measurement: fast mode hold mode 0x64 0x58 temperature and relative humidity measurement: fast mode no hold mode 0x60 0x9c query device device will ack command, no functional effect or response 0x80 0x5d query device response 0x00 0x47 0x2b 0xef 0xc8 write heater control register hold mode 0xe6 read heater control register hold mode 0xe7 read firmware revision ? 0x84 0xf1
SI7034-A10 rev. 1.0 17 5.1. issuing a measurement command the measurement commands instruct the si7034 to perf orm relative humidity and temperature measurements. the procedure to issue any one of these commands is iden tical. while the measurement is in progress, the option of either clock stretching (hold master mode) or not acknowledging read requests (no hold master mode) is available to indicate to the master that the measurem ent is in progress; the chosen command code determines which mode is used. a checksum byte is returned from th e slave for use in checking for transmission errors. the checksum byte will follow the least signif icant measurement byte. the checksum byte is calculated using a crc generator polynomial of x8 + x5 + x4 + 1, with an initialization of 0xfc. in the i 2 c sequence diagrams in the following sections, bits produced by the master and slave are color coded as shown: table 11. i 2 c bit descriptions name symbol description start s sda goes low while scl high. stop p sda goes high while scl high. repeated start sr sda goes low while scl high. it is allowable to generate a stop before the repeated start. sda can transition to high before or after scl goes high in preparation for generating the start. read r read bit = 1 write w write bit = 0 all other bits ? sda value must remain high or low during the entire time scl is high (this is the set up and hold time in figure 1). master slave sequence to perform a measurement and read back result (hold mode) s slave address w a command byte 1 a command byte 2 asr slave address r a clock stretch during measurement temp msb a temp lsb a checksum a humidity msb a humidity lsb a checksum na p
SI7034-A10 18 rev. 1.0 *note: device will nack the slave address byte until conversion is complete. 5.2. reading and wr iting user registers the heater control register allows the user to set the configuration of the si7034. the procedure for accessing this register is described below. a checksum byte is not provided after reading a user register. sequence to perform a measurement and read back result (no hold mode) s slave address w a command byte 1 a command byte 2 asr slave address r na* sr slave address r a temp msb a temp lsb a checksum a humidity msb a humidity lsb a checksum na p sequence to read a register s slave address w a read reg cmd asr slave address r a read data na p sequence to write a register s slave address w a write reg cmd a write data ap
SI7034-A10 rev. 1.0 19 5.3. measuring relative humidity once a relative humidity measurement has been made, the results of the measurement may be converted to percent relative humidity by using the following expression: where: %rh is the measured relati ve humidity value in %rh rh_code is the 16-bit word returned by the si7034 5.4. measuring temperature each time a relative humidity measurement is made a te mperature measurement is also made for the purposes of temperature compensation of the relative humidity me asurement.the results of the temperature measurement may be converted to temperature in degrees celsius (c) using the following expression: where: temperature (c) is the measured temperature value in c temp_code is the 16-bit word returned by the si7034 5.5. firmware revision the internal firmware revision can be read with the following i 2 c transaction: the values in this field are encoded as follows: 0x10 = firmware version 1.0 s slave address w a0x84 a0xf1 asr slave address r a fwrev a na p %rh 100 rh_code 2 16 --------------------------- - = t45 ? 175 temp_code 2 16 --------------------------------- - + =
SI7034-A10 20 rev. 1.0 5.6. electronic serial number the si7034 provides a serial number individualiz ed for each device that can be read via the i 2 c serial interface. two i 2 c commands are required to access the device memory and retrieve the complete serial number. the command sequence, and format of the serial numb er response is described in the figure below: first access: the format of the complete serial number is 64-bits in length, divided into 8 data bytes. the complete serial number sequence is shown below: the snb3 field contains the device identification to distin guish between the different s ilicon labs relative humidity and temperature devices. the value of this field maps to the following devices according to this table: 0x00 or 0xff engineering samples 0x22 = si7034 5.7. heater the si7034 contains an integrated resi stive heating element that may be used to raise the temperature of the sensor. this element can be used to test the sensor, to drive off condensation, or to implement dew-point measurement when the si7034 is used in conjunction with a separate temperature sensor such as another si7034 (the heater will raise the temp erature of the intern al temperature sensor ). the heater can be activated using htre, bit 4 in the heater control register. turning on the heater will reduce the tenden cy of the humidity sensor to accumulate an offset due to ?memory? of sustained high humidity conditions. the heat er current can be configured using bits 3:0 of the heater control register. master slave s slave address w ack 0xfa ack 0x0f ack s slave address r ack sna_3 ack crc ack sna_2 ack crc ack sna_1 ack crc ack sna_0 ack crc nack p 2nd access: s slave address w ack 0xfc ack 0xc9 ack s slave address r ack snb_3 ack snb_2 ack crc ack snb_1 ack snb_0 ack crc nack p sna_3 sna_2 sna_1 sna_0 snb_3 snb_2 snb_1 snb_0
SI7034-A10 rev. 1.0 21 6. control registers reset settings = 0000_0000 table 12. register summary register bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 heater control register rsvd htre heater[3:0] notes: 1. any register not listed here is reserved and must not be written.the result of a read operation on these registers is undefined. 2. except where noted, reserved register bits will always read back as ?1,? and are not affected by write operations. for future compatibility, it is recommended that prior to a write oper ation, registers should be read. then the values read from the rsvd bits should be written back unchanged during the write operation. register 1. heater control register bitd7d6d5d4d3d2d1 d0 name rsvd htre heater [3:0] type r/w r/w bit name function d4 htre 1 = on-chip heater enable 0 = on-chip heater disable d3:d0 heater[3:0] d3 d2 d1 d0 heater current 0000 6.4 ma 0001 9.7 ma 0010 13.1 ma ... 0100 19.6 ma ... 1000 32.4 ma ... 1 1 1 1 53.5 ma d7,d6, d5 rsvd reserved
SI7034-A10 22 rev. 1.0 7. pin descriptions: si7034 (top view) pin name pin # pin description vdd 1 power. this pin is connected to the power supply on the circuit board. scl 2 i 2 c clock dnc 3,6 do not connect electrically. it is recommend ed to solder to floatin g pads for mechanical stability. do not connect to gnd or gnd plane. sda 4 i 2 c data gnd 5 ground. this pin is connected to ground on the circuit board. dnc scl vdd 1 2 3 5 4 gnd sda dnc 6
SI7034-A10 rev. 1.0 23 8. ordering guide table 13. device ordering guide p/n description max. accuracy package operating range (c) packing format temp rh SI7034-A10-im digital temperature/ humidity sensor 0.4 c 4% 6-pin qfn ?40 to +125 c cut tape SI7034-A10-imr digital temperature/ humidity sensor 0.4 c 4% 6-pin qfn ?40 to +125 c tape-and-reel
SI7034-A10 24 rev. 1.0 9. package outline 9.1. package outline: 2x2 6-pin qfn figure 7 illustrates the package details for the si7034. figure 7. si7034 package drawing table 14. package dimensions dimension min nom max a 0.70 0.75 0.80 b 0.30 0.35 0.40 d 2.00 bsc e 2.00 bsc e 1.00 bsc d2 0.60 0.70 0.80 e2 1.50 1.60 1.70 g 0.20 0.25 0.30 h1 0.70 0.75 0.80 h2 1.20 1.25 1.30 l 0.30 0.35 0.40 aaa 0.10 bbb 0.10 ccc 0.08 ddd 0.10 eee 0.05 fff 0.05 notes: 1. all dimensions shown are in millimeters (mm). 2. dimensioning and tolerancing per ansi y14.5m-1994.
SI7034-A10 rev. 1.0 25 10. pcb land pattern and solder mask design figure 8. pcb land pattern dimensions table 15. pcb land pattern dimensions symbol mm c1 2.00 e1.00 x1 0.40 y1 0.75 x2 1.70 y2 0.80 notes: general 1. all dimensions shown are in millimeters (mm). 2. this land pattern design is based on the ipc-7351 guidelines. 3. all dimensions shown are at maximum material condition (mmc). least material condition (lmc) is calculated based on a fabrication allowance of 0.05 mm. solder mask design 4. all metal pads are to be non-solder mask defined (nsmd). clearance between the solder mask and the metal pad is to be 60 m minimum, all the way around the pad. stencil design 5. a stainless steel, laser-cut and electro-pol ished stencil with trapezoidal walls should be used to assure good solder paste release. 6. the stencil thickness should be 0.125 mm (5 mils). 7. the ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins. 8. a 2x1 array of 0.55 mm square openings on 0.90 mm pitch should be used for the center ground pad to achieve a target solder coverage of 50%. card assembly 9. a no-clean, type-3 solder paste is recommended. 10. the recommended card reflow profile is per the jedec/ipc j-std-020 specification for small body components.
SI7034-A10 26 rev. 1.0 11. top marking 11.1. si7034 top marking 11.2. top marking explanation mark method: laser font size: 0.30 mm line 1 marking: circle = 0.25 mm diameter, pin #1 indicator t = manufacturing trace code digit 1 line 2 marking: tt = manufacturing trace code digits 2-3
SI7034-A10 rev. 1.0 27 12. additional reference resources ?? an607: si70xx humidity and temperature sensor designer?s guide
SI7034-A10 28 rev. 1.0 d ocument c hange l ist revision 0.11 to revision 0.3 ? updates to section 1. ?ele ctrical specifications?. ? updated table 2. ?general specifications?. ? updated figure 1. ?i 2 c interface timing diagram?. ? updated table 12. ?i 2 c command table?. ? updated section 4.4. ?pcb assembly?. ? updated section 5.2. ?reading and writing user registers?. ? updated section 5.3. ?measuring relative humidity?. ? updated section 5.4. ?measuring temperature?. ? updated section 5.6. ?ele ctronic serial number?. ? updated section 6. ?control registers?. ? updated section 7. ?p in descriptions?. ? updated section 8. ?package outline?. revision 0.3 to revision 0.4 ? updated features on page 1. ? updated block diagram. ? updated table 1. ? updated table 2. ? updated table 3. ? updated table 4. ? updated table 5. ? updated table 6. ? updated table 7. ? updated table 8. ? updated section 4.4. ? updated table 12. ? updated section 5. ? added section 6. ? updated table 13. ? updated section 9. ? updated section 10. revision 0.4 to revision 0.5 ? added esd specifications to table 7. ? revised heater control register settings. ? updated firmware revision command address. ? corrected pin numbering in figure 7 and figure 8. ? updated table 4, ?humidity sensor,? on page 7. ? updated table 5, ?temperature sensor,? on page 8. ? changed power supply voltage range to 10%. revision 0.5 to revision 0.8 ? updated table 6, ?thermal characteristics,? on page 9. ? updated table 2. ? updated table 10. ? updated section 5.3. ? updated section 5.4. ? updated section 11. revision 0.8 to revision 0.9 ? updated table 2. ? updated footnotes in table 3. ? updated table 4. ? updated descriptions in table 10. ? updated table 13. ? updated section 5.1. ? updated section 5.3. ? added section 5.5. ? updated section 6. revision 0.9 to revision 1.0 ? updated features on page 1. ? updated table 2. ? updated figure 4 ? updated section 5.1.
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