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www.sensirion.com august 2016 - version 3 1 / 20 datasheet sht3x - dis humidity and temperature sensor ? fully calibrated , linearized, and temperature compensated digital output ? wide supply voltage range, from 2.4 v to 5.5 v ? i2c interface with communication speeds up to 1 mhz and two user selectable addresses ? typical a ccuracy of ? 1.5 % rh and ? 0.2 c for sht35 ? very fast start - up and measurement time ? tiny 8 - pin dfn package product summar y sht3x - dis is the next generation o f sensirions temperature and humidity sensors . it builds on a new cmosens? sensor chip that is at the heart of sensirions new humidity and temperature p latform. the sht3x - dis has increased intelligence, reliability and improved accuracy specifications compared to its predecessor . its functionality includes enhanced signal processing, two distinctive and user selectable i2c addresses and co mmunication speeds of up to 1 mhz . the dfn package has a footprint of 2.5 x 2.5 mm 2 while keeping a height of 0.9 mm. this allows for integration of the sht3x - dis into a great variety of applications. additionally, t he wide supply voltage range of 2.4 v to 5.5 v guarantees compatibility with diverse assembly situations . all in all, the sht3x - dis incorporates 15 years of knowledge of sensirion, the leader in the humidity sensor industry. benefits of sensirion s cmosens ? technology ? high reliability and long - term stability ? industry - proven technology with a track record of more than 1 5 years ? designed for mass production ? high process capabilit y ? high signal - to - noise ratio content 1 sensor performance ................................ .................. 2 2 specifications ................................ .............................. 6 3 pin assignment ................................ ........................... 8 4 operation and communication ................................ 9 5 packaging ................................ ................................ .. 15 6 shipping package ................................ .................... 17 7 quality ................................ ................................ ........ 18 8 ordering information ................................ ................ 18 figure 1 functional block diagram of the sht3x - dis . the sensor signals for humidity and temperature are factory calibrated, linearized and compensated for temperatur e and supply voltage dependencies . nreset alert sda scl addr power on reset alert logic reset digital interface rh sensor t sensor data processing & linearization adc adc calibration memory vss vdd vss vdd
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 2 / 20 1 s ensor performanc e humidity sensor specification parameter condition value units sht30 accuracy tolerance 1 t yp. ? 3 % rh m ax. figure 2 - SHT31 accuracy tolerance 1 typ. ? 2 % rh max. figure 3 - sht35 accuracy tolerance 1 typ. 1.5 % rh max. figure 4 - repeatability 2 low 0.25 % rh medium 0.15 % rh high 0.10 % rh resolution typ. 0.01 % rh hysteresis at 25c ? 0.8 % rh specified range 3 extended 4 0 to 100 % rh response time 5 ? 63% 8 6 s long - term drift t yp . 7 < 0.25 % rh/y r table 1 humidity s ensor specification . temperature sensor specification parameter condition value units sht30 a ccuracy tolerance 1 typ., 0c to 65c ? 0.3 c SHT31 accuracy tolerance 1 typ., - 40 c to 90c ? 0.3 c sht35 accuracy tolerance 1 typ., - 40c to 90c 0.2 c repeatability 2 low 0.24 c medium 0.12 c high 0.06 c resolution typ. 0.015 c specified range - - 40 to 125 c response time 8 ? 63% > 2 s long term drift max < 0.03 c/yr table 2 temperature sensor specification . 1 for definition of ty pical and maximum accuracy tolerance, please refer to the document sensirion humidity sensor specification statement. 2 the stated repeatability is 3 times the standard deviation (3) of multiple consecutive measurement s at the stated repeatability and at constant ambient conditions . it is a measure for the noise on the phy sical sensor output. different measurement modes allow for high/medium/low repeatability. 3 specified range refers to the range for w hich the humidity or temperature sensor specification is guara nteed. 4 for details about recommended humidity and temperature operating range, please refer to section 1.1 . 5 time for achiev ing 63% of a humidity step function, valid at 25c and 1m/s airflow. humidity response time in the application depends on the design - in of the sensor. 6 with activ ated art function (see section 4.7 ) the response time can be improved by a factor of 2. 7 ty pical value for operation in normal rh/t operating range , s ee section 1.1 . maximum value is < 0.5 %rh/y r . higher drift values might occur due to contaminant env ironments with vaporized solvents, out - gassing tapes, adhesives, packaging materials, etc. for more det ails please refer to handling instructions. 8 temperature response time s strongly depend on the ty pe of heat ex change, the av ailable sensor surface and the design environment of the sensor in the final application.
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 3 / 20 humidity sensor performance graphs figure 2 tolerance of rh at 25c for sht30 . figure 3 tolerance of rh at 25c for SHT31 . figure 4 t olerance of rh at 25c for sht35 . 0 2 4 6 8 0 10 20 30 40 50 60 70 80 90 100 relative humidity (%rh) sht30 maximal tolerance typical tolerance d rh (%rh) 0 2 4 6 8 0 10 20 30 40 50 60 70 80 90 100 relative humidity (%rh) SHT31 maximal tolerance typical tolerance d rh (%rh) 0 2 4 6 0 10 20 30 40 50 60 70 80 90 100 relative humidity (%rh) sht35 maximal tolerance typical tolerance d rh (%rh)
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 4 / 20 sht30 SHT31 rh (%rh) 100 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 90 3 3 3 3 3 3 3 3 3 80 3 3 3 3 3 3 3 3 3 70 3 3 3 3 3 3 3 3 3 60 3 3 3 3 3 3 3 3 3 50 3 3 3 3 3 3 3 3 3 40 3 3 3 3 3 3 3 3 3 30 3 3 3 3 3 3 3 3 3 20 3 3 3 3 3 3 3 3 3 10 3 3 3 3 3 3 3 3 3 0 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 0 10 20 30 40 50 60 70 80 temperature (c) rh (%rh) 100 2 2 2 2 2 2 2 2 2 90 2 2 2 2 2 2 2 2 2 80 2 2 2 2 2 2 2 2 2 70 2 2 2 2 2 2 2 2 2 60 2 2 2 2 2 2 2 2 2 50 2 2 2 2 2 2 2 2 2 40 2 2 2 2 2 2 2 2 2 30 2 2 2 2 2 2 2 2 2 20 2 2 2 2 2 2 2 2 2 10 2 2 2 2 2 2 2 2 2 0 2 2 2 2 2 2 2 2 2 0 10 20 30 40 50 60 70 80 temperature (c) fi gure 5 typ ical tolerance of rh over t for sht30 . figure 6 typ ical tolerance of rh over t for SHT31 . sht35 rh (%rh) 100 2 2 2 2 2 2 2 2 2 90 2 2 2 2 2 2 2 2 2 80 2 2 2 2 70 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 2 60 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 2 50 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 2 40 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 30 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 20 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 10 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 0 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 0 10 20 30 40 50 60 70 80 temperature (c) figure 7 typical tolerance of rh over t for sht3 5.
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 5 / 20 temperature sensor performance graphs sht30 SHT31 figure 8 temperature accuracy of the sht30 sensor. figure 9 temperature accuracy of the SHT31 sensor. sht35 figure 10 temperature accuracy of the sht35 sensor. 0.0 0.5 1.0 1.5 -40 -20 0 20 40 60 80 100 120 temperature ( c) maximal tolerance typical tolerance d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) 0.0 0.5 1.0 1.5 -40 -20 0 20 40 60 80 100 120 temperature ( c) maximal tolerance typical tolerance d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) 0.0 0.5 1.0 1.5 -40 -20 0 20 40 60 80 100 120 temperature ( c) maximal tolerance typical tolerance d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c) d t ( c)
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 6 / 20 1.1 recommended operating condition the sensor shows best performance when operated within recommended normal temperature and humidity range of 5 c C 60 c and 20 %rh C 80 %rh, respectively. long - term exposure to conditions outside normal range, especially at high humidity, may temporarily offset the rh signal (e.g. +3%rh after 60h kept at >80%rh). after returning into the normal temperature and humidity range the sensor will slowly come back to calibration state by itself. prolonged exposure to extreme conditions may accelerate ageing. to ensure stabl e operation of the humidity sensor, the conditions described in the document shtxx assembly of smd packages, section storage and handling instructions regarding exposure to volatile organic compounds have to be met. please note as well that this does a pply not only to transportation and manufacturing, but also to operation of the sht3x - dis . 2 specifications 2.1 electrical specifications parameter symbol condition min . typ . max . units comments supply v oltage v dd 2.4 3.3 5.5 v power - up/down level v por 2. 1 2.3 2.4 v slew rate change of the supply voltage v dd , slew - - 20 v/ms voltage changes on the vdd line between v dd , min and v dd , max should be slower than the maximum slew rate ; faster slew rates may lead to reset; supply c urrent i dd idle state ( single shot mode ) - 0.2 2.0 ? a c urrent when sensor is not performing a me a surement during single shot mode idle state ( periodic data acquisition mode ) - 45 70 ? a ? c urrent when sensor is not performing a me a surement during periodic data acquisition mode measuring - 800 1500 ? a c urrent consumption while sensor is measuring average - 2 - ? a c urrent consumption (operation with one measurement per second at lowest repeatability , single shot mode ) alert output driving strength ioh 0.8x v dd 1.5x v dd 2.1x v dd ma s ee also section 3.5 heater p ower p heater heater r unning 4. 5 - 33 mw depending on the supply voltage table 3 electrical s pecifications, valid at 25c .
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 7 / 20 2.2 timing specification for the sensor system parameter symbol conditions min. typ. max. units comments power - up time t pu after hard reset, v dd v por - 0.5 1 m s time between v dd reaching v p or and sensor entering idle state soft reset time t sr after soft reset. - 0.5 1 m s time between ack of soft reset command and sensor entering idle state duration of r eset p ulse t resetn 1 - - s see section 3.6 measurement duration t meas,l low repeatability - 2.5 4 ms the three repeatabili ty modes differ with respect to measurement duration, noise level and energy consumption. t meas,m medium repeatability - 4.5 6 ms t meas,h high repeatability - 12.5 15 ms table 4 system t iming s pecification, valid from - 40 c to 125 c and 2.4 v to 5.5 v . 2.3 absolut e m inimum and m aximum r atings stress levels beyond those listed in table 5 may cause permanent damage to the device or affect the reliability of the sensor . these are stress rating s only and functional operation of the device at these conditions is not guaranteed. parameter rating units supply voltage v dd - 0.3 to 6 v max voltage on pins ( pin 1 ( sda ); pin 2 ( addr ); pin 3 ( alert ); pin 4 ( scl ); pin 6 ( nreset )) - 0.3 to vdd+0.3 v input c urrent on any p in 100 ma operating temperature range - 40 to 125 c storage temperature range - 40 to 150 c esd hbm (human body model) 9 4 kv esd cdm (charge device model) 10 750 v table 5 m inimum and maximum rating s ; voltage values may only be applied for short time periods. 9 according to ansi/esda/j edec js - 001 - 2014; aec - q100 - 002. 10 according to ans i/esd s5.3.1 - 2009; aec - q100 - 011 .
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 8 / 20 3 pin a ssignment t he sht3x - dis comes in a tiny 8 - p in dfn package C see table 6 . pin name comments 1 sda serial data; input / output 2 addr address pin; input; connect to either logic high or low , do not leave floating 3 alert indicates alarm condition; output; must be left floating if unused 4 scl serial clock; input / output 5 vdd supply voltage; input 6 nreset reset pin active low; i nput; if not used it is recommend to be left floating 7 r no electrical function; t o be connect ed to vss 8 vss ground table 6 sht3x - dis pin assignment ( transparent top view). dashed lines are only visible if viewed from below . the die pad is internally connected to vss . 3.1 power p ins ( vdd , vss ) the electrical specifications of the sht3x - dis are shown in table 3 . the power supply pins must be decoupled with a 100 nf capacitor that shall be placed as close to the sensor as possible C see figure 11 for a typical application circuit . 3.2 serial c lock and s erial d ata ( scl , sda) scl is used to synchronize the communication between microcontroller and the sensor. the clock frequency can be freely chosen b etween 0 to 1000 khz. c ommands with clock stretching according to i2c standard 11 are supported. the sda pin is used to transfer data to and from the sensor. communication with frequencies up to 400 khz must meet the i2c fast mode 11 standard . communication frequencies up to 1 mhz are supported following the specifications given in table 20 . 11 http://www.nxp.com/documents/user_manual/um10204.pd f both scl and sda lines are open - drain i/os with diodes to vdd and vss. they should be connected to external pull - up resistors (please refer to figure 11 ). a device on the i2c bus must only drive a line to ground. the external pull - up resistors (e.g. r p = 10 k ) are required to pull the signal high. for dimensioning resistor sizes please take bus capacity and communication frequency into account (s ee for example section 7.1 of nxps i2c manual for more details 11 ) . it should be noted that pull - up resistors may be included in i/o circuits of microcontrollers. it is recommended to wire the sensor ac c ording to the application circuit as shown in figure 11 . figure 11 typical a pplication c ircuit . please note that the positioning of the pins does not reflect the position on the real sensor. this is shown in table 6 . 3.3 die p ad ( c enter p ad) the die pad or center pad is visible from below and located in the center of the package. it is electrically connected to vss . hence e lectrical considerations do not impose constraints on the wiring of the die pad. however, due to mechanical reasons it i s recommended to solder the center pad to the pcb. for more information on design - in, please refer to the document shtxx design guide. 3.4 addr p in through the appropriate wiring of the addr p in the i 2 c address can be selected ( see table 7 for the respective addresses) . the addr pin can either be connected to vdd or vss , or it can be used as a selector pin. this means that the address of the sensor can be changed dynamically during operation by switching the level on the addr pin . the only constraint is that the level has to stay constant starting from the i2c start condition until the com munication is finished. th is allows to connect more than two sht3x - dis onto the same bus. the dynamical switching requires individual addr lines to the sensors. 1 2 3 4 5 8 7 6 v dd rr pp 1 0 0 n f addr (2) alert (3) die pad r (7) sda (1) scl (4) vdd (5) vss (8) nreset (6)
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 9 / 20 please note that the i2c address is represented through the 7 msbs of the i2c read or write header. the lsb switches between read or write header. the wiring for the default address is shown in table 7 and figure 11 . the addr pin must not be left floating. please note that only the 7 msbs of the i2c read/write header constitute the i2c address. sht3x - dis i2c address in hex. represent at ion condition i2c address a 0x44 (default) addr ( pin 2) connected to vss i2c address b 0x45 addr ( pin 2) connected to vdd table 7 i2c device address es. 3.5 alert p in the a lert p in may be used to connect to the interrupt pin of a microcontroller. the output of the pin depends on the value of the rh/t reading relativ e to programmable limits. its function is explained in a separate a pplication n ote . if not used, t his pin must be left floating. the pin switches high, when alert conditions are met. the maximum driving loads are listed in table 3 . be aware that self - heating might occur, depending on the amount of current that fl ows. self - heating can be prevented if the alert pin is only used to switch a transistor. 3.6 nreset p in the nreset pin may be used to generate a reset of the sensor. a minimum pulse duration of 1 s is required to reliably trigger a reset of the sensor. it s function is explained in more detail in section 4 . if not used it is recommended to leave the pin floating . 4 operation and communication the sht3x - dis supports i 2c fast mode (and frequencies up to 1000 khz) . clock stretching can be enabled and disabled through the appropriate user command . for detailed information on the i2c protocol, refer to nxp i2c - bus specification 12 . all sht3x - dis commands and data are m apped to a 16 - bit address space. ad d itionally, data and commands are protected with a crc checksum. this increases communication reliability. the 16 bits c ommands to the sensor alrea dy include a 3 bit crc checksum. data sent from and received by the sensor is always succ e eded by an 8 bit crc. in write direction it is mandatory to transmit the checksum, since the sht3x - dis only accepts data if it 12 http://www.nxp.com/documents/user_manual/um10204.pd f is followed by the correct checksum. in read direction it is left to the master to read and process the checksum. 4.1 power - up and c ommunication s tart the sensor starts powering - up after reaching the power - up threshold voltage v por specified in table 3 . after reaching this threshold voltage the sensor needs the time t p u to enter idle state. once the idle state is entered it is ready to receive commands from the master (microcontroller). each transmission sequence begins with a start cond ition (s) and ends with a stop condition (p) as described in the i2c - bus specification. the stop condition is optional. whenever the sensor is powered up, but not performing a measurement or communicating, it automatically enters idle sta te for energy savi ng. this idle state cannot be controlled by the user. 4.2 starting a m easurement a measurement communication sequence consists of a start condition, the i2c write header (7 - bit i2c device address plus 0 as the write bit) and a 16 - bit measurement command. the p roper reception of each byte is indicated by the sensor. it pulls the sda pin low (ack bit) after the falling edge of the 8th scl clock to indicate the reception. a complete measurement cycle is depicted in table 8 . with the acknowledgement of the measurement command, the sht3x - dis starts measuring humidity and temperature. 4.3 measurement c ommands for s ingle s hot d ata a cquisition m ode in this mode one issued measurement command triggers the acquisition of one data pair . each data pair consists of one 16 bit temperature and one 16 bit humidity value (in this order). d uring transmission each data value is always followed by a crc checksum , see section 4.4 . in single shot mode different measurement commands can be selected. the 16 bit commands are shown in table 8 . they differ with respect to repeatability (low, medium and high) and clock stretching (enabled or disabled). the repeatability setting influences t he measurement duration and thus the overall energy consumption of the sens or. this is explained in section 2 .
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 10 / 20 condition hex. c ode repeatability clock s tretching msb lsb high enabled 0x2c 06 medium 0 d low 10 high disabled 0x2 4 0 0 medium 0 b low 16 e.g. 0x2c06: high repeatability measurement with clock stretching enabled table 8 measurement c ommands in single shot mode ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . 4.4 readout of measurement r esults for si ngle s hot m ode after the sensor has completed the measurement, the master can read the measurement results (pair of rh& t) by sending a start condition followed by an i2c read header. the sensor will acknowledge the reception of the read header and send two bytes of data (temperature) followed by one byte crc checksum and another two bytes of data (relative humidity) followed by one byte crc checksum. each byte must be ackn owledged by the microcontroller with an ack condition for the sensor to continue sending data. if the sensor does not receive an ack from the master after any byte of data, it will not continue sending data. the sensor will send the temperature value firs t and then the relative humidity value. after having received the checksum for the humidity value a nack and stop condition should be sent (see table 8 ). the i2c master can abort the read transfer with a nack condition after any data byte if it is not interested in subsequent data, e.g. the crc byte or the second measurement result, in order to save time. in case the user needs humidity and temperature data but does not want to process crc data, it is recommended to read the two temperature bytes of data with the crc byte (without processing the crc data) ; after having re a d the two humidity bytes, the read transfer can be aborted with a with a nack. no clock stretching w hen a command with out clock stretching has been issued, the sensor responds to a read header with a not acknowledge (nack) , if no data is present . clock stretching w hen a command with clock stretching has been issued, the sensor responds to a read header with an ack and subsequently pulls down the scl line. the scl line is pulled down until the measurement is complete. as soon as the measurement is complete, the senso r releases the scl line and send s the measurement results . 4.5 measurement c ommands for periodic d ata a cquisition m ode in this mode one issued measurement command yields a stream of data pairs . each data pair consists of one 16 bit temperature and one 16 bit humidity value (in this order). in periodic mode different measurement commands can be selected. the corresponding 16 bit commands are shown in table 9 . they differ with respect to repeatability (low, medium and high) and data acquisition frequency (0.5, 1, 2, 4 & 10 measurements per second, mps). clock stretching cannot be selected in this mode. the data acquisition frequency and the repeatability setting influences the measurement duration and the current consumption of the sensor. this is explained in section 2 of this datasheet. if a measurement command is issued, while the sensor is busy with a measurement (measurement durations see table 4 ), i t is recommended to issue a break command first (see section 4.8 ). upon reception of the break command the sensor will finish the ongoing measurement and enter the single shot mode .
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 11 / 20 condition hex. c ode repeatability mps msb lsb high 0.5 0x20 32 medium 24 low 2f high 1 0x21 30 medium 26 low 2d high 2 0x22 36 medium 20 low 2b high 4 0x23 34 medium 22 low 29 high 10 0x27 37 medium 21 low 2a e.g. 0x2 130 : 1 high repeatability mps - measurement per second table 9 measurement c ommands for p eriodic data acquisition mode ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . n.b.: at the highest mps setting self - heating of the sensor might occur. 4.6 readout of m easurement r esults for periodic mode transmission of the measurement data can be initiated through the fetch data command shown in table 10 . if no measurement data is present the i2c read header is respond ed with a nack (bit 9 in table 10 ) and the communication stops. after the read out command fetch data has been issued, the data mem ory is cleared , i.e. no measurement data is present. command hex c ode fetch data 0x e0 00 table 10 fetch data command ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . 4.7 art command the art (accelerated response time) feature can be activated by issuing the command in table 11 . after issuing the art command the sensor will start acquiring data with a frequency of 4hz. the art command is structurally similar to any other command in table 9 . hence section 4.5 applies for starting a measurement, section 4.6 for reading out data and section 4.8 for stopping the periodic data acquisition. the art feature can also be evaluated using the evaluation kit ek - h5 from sensirion. command hex code periodic measurement with art 0x2b32 table 11 command for a periodic data acquisition with the art feature ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . 4.8 break command / stop periodic d ata a cquisition m ode the periodic data acquisition mode can be stopped using the break command shown in table 12 . it is recommended to stop the periodic d ata acquisition prior to sending another command (except fetch data command) using the break command. upon reception of the break command the sensor enters the single shot mode , after finishing the ongoing measurement. this can take up to 15 ms, dependin g on the selected repeatability. command hex code break 0x3093 table 12 break c ommand ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . 4.9 reset a system reset of the sht3x - dis can be generated externally by issuing a command (soft reset) or by sending a pulse to the dedicated reset pin (nreset pin). additionally, a system reset is gene rated internally during power - up . during the reset procedure the sensor will not process comma nds. in order to achieve a full reset of the sensor without removing the power supply, it is recommended to use the nreset pin of the sht3x - dis . s ack w i2c address 1 2 3 4 5 6 7 8 9 ack command msb 1 2 3 4 5 6 7 8 9 ack command lsb 10 11 12 13 14 15 16 17 18 16-bit command i2c write header
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 12 / 20 interface reset if communication with the device is lost , the following signal sequence will reset the s erial interface: while leaving sda high, toggle scl nine or more times. this must be followed by a transmission start sequence preceding the next command. this sequence resets the interface only. the status register preserves its content. soft r eset / re - i nitialization the sht3x - dis provides a soft reset mechanism that forces the system into a well - defined state without removing the power supply. when the system is in idle state the soft reset command can be sent to the sht3x - dis . this triggers the se nsor to reset its system controller and reloads calibration data from the memory. in order to start the soft reset procedure the command as shown in table 13 should be sent . it is worth noting that the sensor reloads calibration data prior to every measurement by default. command hex code soft reset 0x30a2 table 13 soft reset c ommand ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . reset through general call additionally, a reset of the sensor can also be generated using the general call mode according to i2c - bus specification 12 . this generates a reset which is functionally identical to using the nreset pin. it is important to understand that a reset generated in this way is not device specific. all devices on the same i2c bus that support the general call mode will perform a res et. additionally, this command only works when the sensor is able to process i2c commands. the appropriate command consists of two bytes and is shown in table 14 . reset through the nreset pin pulling the nreset pin low (see table 6 ) generates a reset similar to a hard reset. the nreset pin is interna lly connected to vdd through a pull - up resistor and hence active low. the nreset pin has to be pulled low for a minimum of 1 s to generate a reset of the sensor. command code address byte 0x00 second byte 0x06 reset command using the general call ad dress 0x0006 table 14 reset through the general c all address ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ). hard re s et a hard reset is achieved by switching the supply voltage to the vdd pin off and then on again. in order to prevent powering the sensor over the esd diodes, the voltage to pins 1 ( sda ), 4 ( scl ) and 2 (addr) also needs to be removed. 4.10 heater the heater can be switched on and off by command, see table below. the status is l isted in the status register. after a reset the heater is disabled (default condition). command hex code msb lsb heater enable 0x30 6d heater disabled 66 table 15 heater command ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . 4.11 status register the status register contains information on the operational status of the heater, the alert mode and on the execution status of the last command and the last write sequence. the command to read out the status register is shown in table 16 whereas a description of the content can be found in table 17 . s ack general call address 1 2 3 4 5 6 7 8 9 ack reset command 1 2 3 4 5 6 7 8 9 general call 1 st byte general call 2 nd byte
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 13 / 20 command hex c ode read out of status register 0xf32d table 16 command to read out the status register ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . bit field description default value 15 alert pending s tatus '0': no pending alerts '1': at least one pending alert 1 14 reserved 0 13 heater s tat us 0 : heater off 1 : heater on 0 12 reserved 0 11 rh tracking alert 0 : no alert 1 . alert 0 10 t tracking alert 0 : no alert 1 . alert 0 9: 5 reserved xxxxx 4 system reset detected '0': no reset detected since last clear status register command '1': reset detected (hard reset, soft reset command or supply fail) 1 3 :2 reserved 0 0 1 command status '0': last command executed successfully '1': last command not processed. it was either invalid, failed the integrated command checksum 0 0 write data checksum status '0': checksum of last write transfer was correct '1': checksum of last write transfer failed 0 table 17 description of the status register. clear status register all flags (bit 15, 11, 10, 4) in the status register can be cleared (set to zero ) by sending the command shown in table 18 . command hex code clear status register 0x 30 41 table 18 command to clear the status register ( clear blocks are controlled by the microcontroller, grey blocks by the sensor ) . 4.12 checksum c alculation the 8 - bit crc checksum transmitted after each data word is generated by a crc algorithm . its properties are displayed in table 19 . the crc covers the contents of the two previously transmitted data bytes. to calculate the checksum only these two previously transmitted data bytes are used. property value name crc - 8 width 8 bit protected d ata read and/or write data polynomial 0x31 (x 8 + x 5 + x 4 + 1) initialization 0xff reflect input false reflect output false final xor 0x00 examples crc (0xbeef) = 0x92 table 19 i2c crc properties. 4.13 conversion of s ignal o utput measurement data is always transferred as 16 - bit values (unsigned integer) . these values are alrea dy linearized and compensated for temperature and supply voltage effects . converting those raw values into a physical scale can be achieved using the following formulas. relative humidity conversion formula (result in %rh): temperature conversion formula (result in c & f ): s rh and s t denote the raw sensor output for humidity and temperat ure, respectively. the formulas work only correct ly when s rh and s t are used in decimal representation . 1 ? ? ? 16 rh 2 s 100 rh ? ? ? ? 1 1 ? ? ? ? ? ? ? ? ? ? ? ? 16 t 16 t 2 s 315 49 f t 2 s 175 45 c t
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 14 / 20 4.14 communication t iming parameter symbol conditions min. typ. max. units comments scl clock frequency f scl 0 - 1000 khz hold time (repeated) start condition t hd;sta after this period, the first clock pulse is generated 0.24 - - s low period of the scl clock t low 0.65 - - s high period of the scl clock t high 0.26 - - s sda hold time t hd;dat 0 - 250 ns transmitting data 0 - - ns receiving data sda set - up time t su;dat 100 - - ns scl/sda rise time t r - - 300 ns scl/sda fall time t f - - 300 ns sda valid time t vd;dat - - 0.9 s set - up time for a repeated start condition t su;sta 0.6 - - s set - up time for stop condition t su;sto 0.6 - - s capacitive load on bus line cb - - 400 pf low level input voltage v il - 0.5 - 0.3x v dd v high level input voltage v ih 0.7x v dd - 1x v dd v low level output voltage v ol 3 ma sink current - - 0.66 v table 20 communication timing specifications for i2c fm (fast mode) , s pecification s are at 25c and typical vdd . the numbers above are values according to the i2c specification ( um10204, rev. 6, april 4, 2014 ) . figure 12 timing diagram for digital input/output pads. sda directions are seen from the sensor. bold sda lines are controlled by the sensor, plain sda lines are controlled by the micro - controller. note that sda valid read time is triggered by falling edge of prece ding toggle . scl 7 0% 3 0% t low 1/f scl t high t r t f sda 7 0% 3 0% t su;dat t hd;dat data in t r sda 7 0% 3 0% data out t vd ;dat t f
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 15 / 20 5 packaging sht3x - dis sensors are provided in a n open - cavity dfn package. dfn stands for dual flat no leads. the humidity sensor opening is centered on the top side of the package. the sensor chip is made of silic on and is mounted to a lead frame. the latter is made of cu plated with ni/pd/au. chip and lead frame are overmolded by a n epoxy - based mold compound leaving the central die pad and i/o pins exposed for mechanical and electrical connection . please note that the side walls of the sensor are diced and therefore these diced lead frame surfaces are not covered with the respective plating. the package (except for the humidity sensor opening) follows jedec publication 95, design registration 4.20, small scale plas tic quad and dual inline, square and rectangular, no - lead packages (with optional thermal enhancements) small scale (qfn/son) , issue d.01, september 2009. sht3x - dis has a moisture sensitivity level (msl) of 1, according to ipc/jedec j - std - 020. at the sa me time, it is recommended to further process the sensors within 1 year after date of delivery. 5.1 traceability all sht3x - dis sensors are laser marked for easy identification and traceability. the marking on the sensor top side consists of a pin - 1 indicator and two lines of text . the top line consist of the pi n - 1 indicator which is located in the top left corner and the product name. the small letter x stands for the accuracy class. the bottom line consists of 6 letters. the first two digits xy (= di ) describe the output mode. the third letter (a) represents the manufacturing year (4 = 2014, 5 = 2015, etc). the last three digits (bcd) represent an alphanumeric tracking code. that code can be decoded by sensirion only and allows for tracking on batch level through production, calibration and testing C and will be provided upon justified request. if viewed from below pin 1 i s indicated by triangular shaped cut in the otherwise rectangular die pad. the dimension s of the triangular cut are shown in figure 14 through the lab els t1 & t2 . figure 13 top v iew of the sht3x - dis illustrating the laser marking. s h t 3 x x y a b c d
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 16 / 20 5.2 package outline figure 14 dimensional drawing of sht3x - dis sensor package parameter symbol min nom. max units comments package h eight a 0.8 0.9 1 mm leadframe h eight a3 - 0.2 - mm pad wi dth b 0.2 0.25 0.3 mm package w idth d 2.4 2.5 2.6 mm center p ad l ength d2 1 1.1 1.2 mm package l ength e 2.4 2.5 2.6 mm center pad w idth e2 1.7 1.8 1.9 mm pad p itch e - 0.5 mm pad l ength l 0.3 0.35 0.4 mm max c avity s - - 1.5 mm only as guidance. this value includes all tolerances , including displacement tolerances . typically the opening will be smaller. center p ad marking t1xt2 - 0.3x45 - mm indicates the position of pin 1 table 21 package o utline . 5.3 land p attern figure 15 shows the land pattern. the land pattern is understood to be the open metal areas on the pcb, onto which the dfn pads are soldered. the solder mask is understood to be the insulating layer on top of the pcb covering the copper traces . it is recommended to design the solder pads as a non - solder mask defined (nsmd) type. for nsmd pads, the solder mask opening should provid e a 60 m to 75 m design clearance between any copper pad and solder mask. as the pad p itch is only 0.5 mm we recommend to have one solder mask opening for all 4 i/o p ads on one side. for solder paste printing it is recommended to use a laser - cut, stainless steel stenci l with electro - polished trapezoidal walls and with 0.1 or 0.125 mm stencil thickness . t he length of the stencil apertures f or the i/o pads should be the same as the pcb pads . however, the position of the stencil apertures should have an offset of 0.1 mm aw ay from the center of the package. the die pad aperture should cover about 70 C 90 % of the die pad area C thus it should have a size of about 0. 9 mm x 1.6 mm . for information on the soldering process and further recommendation on the ass e mbly process plea se consult the application note ht_an_shtxx_assembly_of_smd_packages , which can be found on the sensirion webpage.
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 17 / 20 figure 15 recommended metal land pattern (left) and stencil apertures (right) for the sht3x - dis . the dashed lines represent the outer dimension of the dfn package. the pcb pads (left) and stencil apertures (right) are indicated through the shaded areas. 6 shipping package figure 16 technical drawing of the packaging tape with sensor orientation in tape. header tape is to the right and trailer tape to the left on this drawing. dimensions are given in millimeters. 1 . 7 0 . 2 5 1 0 . 5 0 . 5 0 . 5 0.55 0.3x45 0 . 3 7 5 0.2 0.75 0 . 4 0.9 1 . 6 0.55 0 . 5 0 . 5 0 . 5 0 . 2 5 0.55 0 . 4 5 0.8 0 . 3 7 5 0.3 land pattern stencil aperture sensor outline tolerances - unless noted 1pl .2 2pl .10 a = 2.75 b = 2.75 k = 1.20 0 0 0 notes: 1. 10 sprocket hole pitch cumulative tolerance 0.2 2. pocket position relative to sprocket hole measured as true position of pocket, not pocket hole 3. a0 and b0 are calculated on a plane at a distance "r" above the bottom of the pocket a 0 k 0 b 0 r 0.25 typ. section a - a 0.30 .05 a r 0.2 max. 0.30 .05 2.00 .05 see note 2 4.00 4.00 see note 1 ?1.5 +.1 /-0.0 ?1.00 min 1.75 .1 12.0 +0.3/-0.1 5.50 .05 see note 2 a b detail b
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 18 / 20 7 quality qualification of the sht3x - dis is performed based on the aec q 100 qualification test method. 7.1 material contents the device is fully rohs and weee compliant, e.g. free of pb, cd, and hg. 8 ordering information the sht3x - dis can be ordered in tape and reel packaging with different sizes, see table 22 . the reels are sealed into antistatic esd ba gs. the document sht3x shipping package that shows the details about the shipping package is available upon request. name quantity order number sht30 - dis - b2.5ks 2500 1 - 101400 - 01 sht30 - dis - b10ks 10000 1 - 101173 - 01 SHT31 - dis - b2.5ks 2500 1 - 101386 - 01 SHT31 - dis - b10ks 10000 1 - 101147 - 01 sht35 - dis - b2.5ks 2500 1 - 101388 - 01 sht35 - dis - b10ks 10000 1 - 101479 - 01 table 22 sht3x - dis ordering options. 9 further information for more in - depth information on the sht3x - dis and its application please consult the following documents: document name description source sht3x shipping package information on tape, reel and shipping bags (technical drawing and dimensions) available upon request shtxx assembly of smd packages assembly guide (soldering instruction s ) available for download at the sensirion humidity sensors download center: www.sensirion.com/humidity - download shtxx design guide design guidelines for designing sht xx humidity sensors into applications available for download at the sensirion humidity sensors download center: www.sensirion.com/humidity - download shtxx handling instructions guidelines for proper handling of shtxx humidity sensors available for download at the sensirion humidity sensors download center: www.sensirion.com/humidity - download sensirion humidity sensor specification st atement definition of sensor specifications. available for download at the sensirion humidity sensors download center: www.sensirion.com/humidity - download table 23 documents containing further information relevant for the sht3x - dis .
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 19 / 20 revision history date version page(s) changes october 2015 1 - june 2016 2 2 - 4 6 7 7 11 17 specifications for sht35 added esd specifications updated table 6 comments section updated figure 11 updated according to table 6 updated information about data memory to: after the read out command fe tch data has been issued, the data memory is reset, i.e. no measurement data is present. ordering information in table 22 updated august 2016 3 6 7 7 8 8 4 updated table 3 updated table 4 updated information on esd testing norm updated table 6 figure 11 and table 6 updated figure 7 updated
datasheet sht3x - dis www.sensirion.com august 2016 - version 3 20 / 20 important no tic es warning, personal injury do not use this product as safety or emergency stop devices or in any other application where failure of the product could result in personal injury. do not use this product for applications other than its intended and authorized use. before installing, handling, using or servicing this produ ct, please consult the data sheet and application notes. failure to comply with these instructions could result in death or serious injury. if the buyer shall purchase or use sensirion products for any unintended or unauthorized application, buyer shall d efend, indemnify and hold harmless sensirion and its officers, employees, subsidiaries, affiliates and distributors against all claims, costs, damages and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if sensirion shall be allegedly negligent with respect to the design or the manufacture of the product. esd precautions the inherent design of this component causes it to be sensitiv e to electrostatic discharge (esd). to prevent esd - induced damage and/or degradation, take customary and statutory esd precautions when handling this product. see application note esd, latchup and emc for more information. warranty sensirion warrants solely to the original purchaser of this product for a period of 12 months (one year) from the date of delivery that this product shall be of the quality, material and workmanship defined in sensirions published specifications of the pr oduct. within such period, if proven to be defective, sensirion shall repair and/or replace this product, in sensirion s discretion, free of charge to the buyer, provided that: ? notice in writing describing the defects shall be given to sensirion within fou rteen (14) days after their appearance; ? such defects shall be found, to sensirions reasonable satisfaction, to have arisen from sensirions faulty design, material, or workmanship; ? the defective product shall be returned to sensirions factory at the bu yers expense; and ? the warranty period for any repaired or replaced product shall be limited to the unexpired portion of the original period. this warranty does not apply to any equipment which has not been installed and used within the specifications reco mmended by sensirion for the intended and proper use of the equipment. except for the warranties expressly set forth herein, sensirion makes no warranties, either express or implied, with respect to the product. any and all warranties, including without li mitation, warranties of merchantability or fitness for a particular purpose, are expressly excluded and declined. sensirion is only liable for defects of this product arising under the conditions of operation provided for in the data sheet and proper use o f the goods. sensirion explicitly disclaims all warranties, express or implied, for any period during which the goods are operated or stored not in accordance with the technical specifications. sensirion does not assume any liability arising out of any app lication or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. all operating parameters, including without limitation recommended parameters, must be validated f or each customers applications by customers technical experts. recommended parameters can and do vary in different applications. sensirion reserves the right, without further notice, (i) to change the product specifications and/or the information in this document and (ii) to improve reliability, functions and design of this product. copyright ? 2016, by sensirion. cmosens ? is a trademark of sensirion all rights reserved . headquarters and subsidiaries sensirion ag laubisruetistr. 50 ch - 8712 staefa zh switzerland phone: +41 44 306 40 00 fax: +41 44 306 40 30 info@sensirion.com www.sensirion.com sensirion inc. usa phone: +1 805 409 4900 info_us@sensirion.com www.sensirion.com sensirion japan co. ltd. phone: +81 3 3444 4940 info - jp@sensirion.co m www.sensirion.co.jp sensirion korea co. ltd. phone: +82 31 337 7700~3 info - kr@sensirion.co m www.sensirion.co.kr sensirion china co. ltd. phone: +86 755 8252 1501 info - cn@sensirion.com http://www.sensirion.com.cn/ sensirion ag (germany) phone: +41 44 927 11 66 to find your local representative, please visit www.sensirion.com/contact

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