SHT11

Datasheet SHT1x (SHT10, SHT11, SHT15) Humidity and Temperature Sensor • • • • • Fully calibrated Digital output Low power consumption Excellent long term stability SMD type package – reflow solderable Product Summary Each SHT1x is individually calibrated in a precision humidity chamber. The calibration coefficients are programmed into an OTP memory on the chip. These coefficients are used to internally calibrate the signals from the sensors. The 2-wire serial interface and internal voltage regulation allows for easy and fast system integration. The tiny size and low power consumption makes SHT1x the ultimate choice for even the most demanding applications. Dimensions Sensor Chip NC NC 1 NC 3 4 A5Z 11 Material Contents NC NC 2.5 ±0.1 2.2 MAX 2 SHT1x is supplied in a surface-mountable LCC (Leadless Chip Carrier) which is approved for standard reflow soldering processes. The same sensor is also available with pins (SHT7x) or on flex print (SHTA1). SHT1x V4 – for which this datasheet applies – features a version 4 Silicon sensor chip. Besides a humidity and a temperature sensor the chip contains an amplifier, A/D converter, OTP memory and a digital interface. V4 sensors can be identified by the alpha-numeric traceability code on the sensor cap – see example “A5Z” code on Figure 1. 0.6 ±0.1 sensor opening 5.2 ±0.2 4.2 ±0.1 1.27 ±0.05 1.5 ±0.2 2.0 ±0.1 1.5 ±0.1 1.83 ±0.05 7.47 ±0.05 0.95 ±0.1 SHT1x (including SHT10, SHT11 and SHT15) is Sensirion’s family of surface mountable relative humidity and temperature sensors. The sensors integrate sensor elements plus signal processing on a tiny foot print and provide a fully calibrated digital output. A unique capacitive sensor element is used for measuring relative humidity while temperature is measured by a band-gap sensor. The applied CMOSens® technology guarantees excellent reliability and long term stability. Both sensors are seamlessly coupled to a 14bit analog to digital converter and a serial interface circuit. This results in superior signal quality, a fast response time and insensitivity to external disturbances (EMC). NC 3.3 ±0.1 2.6 MAX 4.93 ±0.05 0.8 ±0.1 While the sensor is made of a CMOS chip the sensor housing consists of an LCP cap with epoxy glob top on an FR4 substrate. The device is fully RoHS and WEEE compliant, thus it is free of Pb, Cd, Hg, Cr(6+), PBB and PBDE. Evaluation Kits Figure 1: Drawing of SHT1x sensor packaging, dimensions in mm (1mm = 0.039inch). Sensor label gives “11” for SHT11 as an example. Contacts are assigned as follows: 1:GND, 2:DATA, 3:SCK, 4:VDD. For sensor trial measurements, for qualification of the sensor or even experimental application of the sensor there is an evaluation kit EK-H2 available including sensor, hard and software to interface with a computer. For more sophisticated and demanding measurements a multi port evaluation kit EK-H3 is available which allows for parallel application of up to 20 sensors. Version 4.0 – July 2008 Datasheet SHT1x Sensor Performance Relative Humidity123 Parameter Temperature45 Condition min 0.4 8 Resolution 1 Accuracy 2 SHT11 Repeatability Replacement Hysteresis %RH ±2.0 see Figure 2 %RH ±0.1 fully interchangeable %RH ±1 %RH ±3 4.5V 0 0.1 5 MHz VDD < 4.5V 0 0.1 1 MHz TSCKx SCK hi/low time 100 TR/TF SCK rise/fall time 1 200 * ns 10% Figure 12: "Transmission Start" sequence ns OL = 5pF 3.5 10 20 ns OL = 100pF 30 40 200 ns ** ** ** ns The subsequent command consists of three address bits (only ‘000’ is supported) and five command bits. The SHT1x indicates the proper reception of a command by pulling the DATA pin low (ACK bit) after the falling edge of the 8th SCK clock. The DATA line is released (and goes high) after the falling edge of the 9th SCK clock. Command Reserved Measure Temperature Measure Relative Humidity Read Status Register Write Status Register Reserved Soft reset, resets the interface, clears the status register to default values. Wait minimum 11 ms before next command TFO DATA fall time TRO DATA rise time TV DATA valid time 200 250 *** ns TSU DATA setup time 100 150 *** ns Table 4: SHT1x list of commands THO DATA hold time 10 **** ns 3.3 * TR_max + TF_max = (FSCK)-1 – TSCKH – TSCKL ** TR0 is determined by the RP*Cbus time-constant at DATA line *** TV_max and TSU_max depend on external pull-up resistor (RP) and total bus line capacitance (Cbus) at DATA line **** TH0_max < TV – max (TR0, TF0) 15 Table 3: SHT1x I/O signal characteristics, OL stands for Output Load, entities are displayed in Figure 11. 3 Communication with Sensor 3.1 Start up Sensor As a first step the sensor is powered up to chosen supply voltage VDD. The slew rate during power up shall not fall below 1V/ms. After power-up the sensor needs 11ms to get to Sleep State. No commands must be sent before that time. 3.2 Sending a Command To initiate a transmission, a Transmission Start sequence has to be issued. It consists of a lowering of the DATA line while SCK is high, followed by a low pulse on SCK and raising DATA again while SCK is still high – see Figure 12. www.sensirion.com 90% 10% Figure 11: Timing Diagram, abbreviations are explained in Table 3. Bold DATA line is controlled by the sensor, plain DATA line is controlled by the micro-controller. Both valid times refer to the left SCK toggle. Parameter DATA Code 0000x 00011 00101 00111 00110 0101x-1110x 11110 Measurement of RH and T After issuing a measurement command (‘00000101’ for relative humidity, ‘00000011’ for temperature) the controller has to wait for the measurement to complete. This takes a maximum of 20/80/320 ms for a 8/12/14bit measurement. The time varies with the speed of the internal oscillator and can be lower by up to 30%. To signal the completion of a measurement, the SHT1x pulls data line low and enters Idle Mode. The controller must wait for this Data Ready signal before restarting SCK to readout the data. Measurement data is stored until readout, therefore the controller can continue with other tasks and readout at its convenience. Two bytes of measurement data and one byte of CRC checksum (optional) will then be transmitted. The micro controller must acknowledge each byte by pulling the DATA line low. All values are MSB first, right justified (e.g. the 5th SCK is MSB for a 12bit value, for a 8bit result the first byte is not used). Communication terminates after the acknowledge bit of the CRC data. If CRC-8 checksum is not used the controller may terminate the communication after the measurement data LSB by keeping ACK high. The device automatically returns to Sleep Mode after measurement and communication are completed. Version 4.0 – July 2008 6/11 Datasheet SHT1x Important: To keep self heating below 0.1°C, SHT1x should not be active for more than 10% of the time – e.g. maximum one measurement per second at 12bit accuracy shall be made. Status Register Some of the advanced functions of the SHT1x such as selecting measurement resolution, end of battery notice or using the heater may be activated by sending a command to the status register. The following section gives a brief overview of these features. A more detailed description is available in the Application Note “Status Register”. 3.4 Connection reset sequence If communication with the device is lost the following signal sequence will reset the serial interface: While leaving DATA high, toggle SCK nine or more times – see Figure 13. 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. 0 0 0 0 0 1 1 0 Status Register ACK 90% 9 4-8 ACK Bit 7 3 2 2 TS 10% Transmission Start Figure 14: Status Register Write Figure 13: Connection Reset Sequence 0 0 0 0 0 1 1 1 Status Register Checksum ACK 10% ACK Bit 7 TS 90% DATA ACK Bit 7 Figure 15: Status Register Read 3.5 CRC-8 Checksum calculation The whole digital transmission is secured by an 8bit checksum. It ensures that any wrong data can be detected and eliminated. As described above this is an additional feature of which may be used or abandoned. Please consult Application Note “CRC-8 Checksum Calculation” for information on how to calculate the CRC. LSB ACK Wait for 0 0 DATA ready 0 0 0 Command MSB ACK TS Examples of full communication cycle are displayed in Figures 15 and 16. LSb ACK SCK 1 After the command Status Register Read or Status Register Write – see Table 4 – the content of 8 bits of the status register may be read out or written. For the communication compare Figures 16 and 17 – the assignation of the bits is displayed in Table 5. Checksum Figure 16: Overview of Measurement Sequence. TS = Transmission Start, MSB = Most Significant Byte, LSB = Last Significant Byte, LSb = Last Significant Bit. Transmission Start Address = ‘000’ A2 A1 A0 C4 Command = ‘00101’ C3 C2 C1 C0 Measurement (80ms for 12bit) ACK SCK DATA A2 Idle Bits 14 13 15 12 MSb 11 10 A1 A0 9 C4 C3 C2 C1 C0 12bit Humidity Data ACK 7 6 5 8 Sensor pulls DATA line low after completion of measurement ACK 4 3 2 1 LSb 0 Skip ACK to end transmission (if no CRC is used) ACK SCK DATA 15 14 MSb 7 13 6 5 12 11 10 9 CRC-8 Checksum 4 3 2 1 8 ACK LSb 0 7 6 5 ACK Sleep (wait for next measurement) ACK Skip ACK to end transmission 4 3 2 1 0 ACK Transmission Start SCK DATA 7 6 5 4 3 2 1 0 Figure 17: Example RH measurement sequence for value “0000’1001“0011’0001” = 2353 = 75.79 %RH (without temperature compensation). DATA valid times are given and referenced in boxes on DATA line. Bold DATA lines are controlled by sensor while plain lines are controlled by the micro-controller. www.sensirion.com Version 4.0 – July 2008 7/11 Datasheet SHT1x Bit Type Description Default 7 reserved 0 End of Battery (low voltage No default value, detection) bit is only updated 6 R X ‘0’ for VDD > 2.47 after a ‘1’ for VDD < 2.47 measurement 5 reserved 0 4 reserved 0 3 For Testing only, do not use 0 2 R/W Heater 0 off 1 R/W no reload from OTP 0 reload ’1’ = 8bit RH / 12bit Temp. 12bit RH resolution 0 R/W 0 14bit Temp. ’0’ = 12bit RH / 14bit Temp. resolution Table 5: Status Register Bits Heater: An on chip heating element can be addressed by writing a command into status register. The heater may increase the temperature of the sensor by 5 – 10°C12 beyond ambient temperature. The heater draws roughly 8mA @ 5V supply voltage. For example the heater can be helpful for functionality analysis: Humidity and temperature readings before and after applying the heater are compared. Temperature shall increase while relative humidity decreases at the same time. Dew point shall remain the same. Please note: The temperature reading will display the temperature of the heated sensor element and not ambient temperature. Furthermore, the sensor is not qualified for continuous application of the heater. 4 Conversion of Signal Output 4.1 Relative Humidity For compensating non-linearity of the humidity sensor – see Figure 18 – and for obtaining the full accuracy of the sensor it is recommended to convert the humidity readout (SORH) with the following formula with coefficients given in Table 6: RH linear = c 1 + c 2 ⋅ SO RH + c 3 ⋅ SO RH (%RH) 2 www.sensirion.com c2 0.0367 0.5872 c3 -1.5955E-6 -4.0845E-4 Table 6: Optimized V4 humidity conversion coefficients The values given in Table 6 are newly introduced and provide optimized accuracy for V4 sensors along the full measurement range. The parameter set cx*, which has been proposed in earlier datasheets, which was optimized for V3 sensors, still applies to V4 sensors and is given in Table 7 for reference. SORH 12 bit 8 bit c1* -4.0000 -4.0000 c2* 0.0405 0.6480 c3* -2.8000E-6 -7.2000E-4 For simplified, less computation intense conversion formulas see Application Note “RH and Temperature NonLinearity Compensation”. Values higher than 99% RH indicate fully saturated air and must be processed and displayed as 100%RH13. Please note that the humidity sensor has no significant voltage dependency. 100% Relative Humidity End of Battery function detects and notifies VDD voltages below 2.47 V. Accuracy is ±0.05 V. Corresponds to 9 – 18°F c1 -2.0468 -2.0468 Table 7: V3 humidity conversion coefficients, which also apply to V4. Measurement resolution: The default measurement resolution of 14bit (temperature) and 12bit (humidity) can be reduced to 12 and 8bit. This is especially useful in high speed or extreme low power applications. 12 SORH 12 bit 8 bit 80% 60% 40% 20% 0% 0 500 1000 1500 2000 2500 3000 3500 SORH sensor readout (12bit) Figure 18: Conversion from SORH to relative humidity 4.2 Temperature compensation of Humidity Signal For temperatures significantly different from 25°C (~77°F) the humidity signal requires a temperature compensation. The temperature correction corresponds roughly to 0.12%RH/°C @ 50%RH. Coefficients for the temperature compensation are given in Table 8. RH true = (T°C − 25) ⋅ (t 1 + t 2 ⋅ SO RH ) + RH linear SORH 12 bit 8 bit t1 0.01 0.01 t2 0.00008 0.00128 Table 8: Temperature compensation coefficients14 13 If wetted excessively (strong condensation of water on sensor surface), sensor output signal can drop below 100%RH (even below 0%RH in some cases), but the sensor will recover completely when water droplets evaporate. The sensor is not damaged by water immersion or condensation. 14 Coefficients apply both to V3 as well as to V4 sensors. Version 4.0 – July 2008 8/11 Datasheet SHT1x 4.3 Temperature The band-gap PTAT (Proportional To Absolute Temperature) temperature sensor is very linear by design. Use the following formula to convert digital readout (SOT) to temperature value, with coefficients given in Table 9: T = d1 + d 2 ⋅ SO T VDD 5V 4V 3.5V 3V 2.5V d1 (°C) -40.1 -39.8 -39.7 -39.6 -39.4 d1 (°F) -40.2 -39.6 -39.5 -39.3 -38.9 SOT 14bit 12bit d2 (°C) 0.01 0.04 d2 (°F) 0.018 0.072 Table 9: Temperature conversion coefficients15. 4.4 Dew Point SHT1x is not measuring dew point directly, however dew point can be derived from humidity and temperature readings. Since humidity and temperature are both measured on the same monolithic chip, the SHT1x allows superb dew point measurements. For dew point (Td) calculations there are various formulas to be applied, most of them quite complicated. For the temperature range of -40 – 50°C the following approximation provides good accuracy with parameters given in Table 10: Tn (°C) 243.12 272.62 If sensors are qualified for assemblies or devices, please make sure that they experience same conditions as the reference sensor. It should be taken into account that response times in assemblies may be longer, hence enough dwell time for the measurement shall be granted. For detailed information please consult Application Note “Qualification Guide”. The SHT1x sensor series were tested according to AECQ100 Rev. F qualification test method. Sensor specifications are tested to prevail under the AEC-Q100 temperature grade 2 test conditions listed in Table 1116. Sensor performance under other test conditions cannot be guaranteed and is not part of the sensor specifications. Especially, no guarantee can be given for sensor performance in the field or for customer’s specific application. Please contact Sensirion for detailed information. Environment Standard HTSL 125°C, 1000 hours TC UHST -50°C - 125°C, 1000 cycles Acc. JESD22-A104-C 130°C / 85%RH, 96h THU 85°C / 85%RH, 1000h Results17 Within specifications Within specifications Within specifications Within specifications Qualified ESD immunity MIL STD 883E, method 3015 (Human Body Model at ±2kV) Latch-up force current of ±100mA with Qualified Tamb = 80°C, acc. JEDEC 17  RH  m ⋅ T ln +  100%  Tn + T Td (RH, T ) = Tn ⋅  RH  m ⋅ T m − ln −  100%  Tn + T Temperature Range Above water, 0 – 50°C Above ice, -40 – 0°C 5 Environmental Stability m 17.62 22.46 Table 10: Parameters for dew point (Td) calculation. Please note that “ln(…)” denotes the natural logarithm. For RH and T the linearized and compensated values for relative humidity and temperature shall be applied. For more information on dew point calculation see Application Note “Dew point calculation”. Table 11: Qualification tests: HTSL = High Temperature Storage Lifetime, TC = Temperature Cycles, UHST = Unbiased Highly accelerated temperature and humidity Test, THU = Temperature humidity unbiased 6 Packaging 6.1 Packaging type SHT1x are supplied in a surface mountable LCC (Leadless Chip Carrier) type package. The sensor housing consists of a Liquid Crystal Polymer (LCP) cap with epoxy glob top on a standard 0.8mm FR4 substrate. The device is fully RoHS and WEEE compliant – it is free of of Pb, Cd, Hg, Cr(6+), PBB and PBDE. 16 15 Temperature coefficients have slightly been adjusted compared to datasheet SHTxx version 3.01. Coefficients apply to V3 as well as V4 sensors. www.sensirion.com Sensor operation temperature range is -40 to 105°C according to AEC-Q100 temperature grade 2. 17 According to accuracy and long term drift specification given on Page 2. Version 4.0 – July 2008 9/11 Datasheet SHT1x Device size is 7.47 x 4.93 x 2.5 mm (0.29 x 0.19 x 0.1 inch), see Figure 1, weight is 100 mg. 6.2 Traceability Information All SHT1x are marked with an alphanumeric, three digit code on the chip cap (for reference: V3 sensors were labeled with numeric codes) – see “A5Z” on Figure 1. The lot numbers allow full traceability through production, calibration and testing. No information can be derived from the code directly, respective data is stored at Sensirion and is provided upon request. Labels on the reels are displayed in Figures 19 and 20, they both give traceability information. 6.3 Shipping Package SHT1x are shipped in 12mm tape at 100pcs, 400pcs and 2000pcs – for details see Figure 21 and Table 12. Reels are individually labeled with barcode and human readable labels. Sensor Type SHT10 SHT11 SHT15 Packaging Tape & Reel Tape & Reel Tape & Reel Tape & Reel Tape & Reel Tape & Reel Quantity 2000 100 400 2000 100 400 Order Number 1-100218-04 1-100051-04 1-100098-04 1-100524-04 1-100085-04 1-100093-04 Table 12: Packaging types per sensor type. Lot No.: Quantity: RoHS: XX0-04-YRRRRTTTT RRRR Compliant Dimensions of packaging tape is given in Figure 21. All tapes have a minimum of 480mm empty leader tape (first pockets of the tape) and a minimum of 300mm empty trailer tape (last pockets of the tape). Lot No. Figure 19: First label on reel: XX = Sensor Type (11 for SHT11), 04 = Chip Version (V4), Y = last digit of year, RRRR = number of sensors on reel, TTTT = Traceability Code. Ø1.50 MIN 1.00 0.30 ± 0.05 12.00 Ø1.50 MIN 12.0 ± 0.3 5.50 ± 0.05 1.75 ± 0.10 2.00 ± 0.05 R0.3 MAX 11 A5Z 5.80 R0.5 TYP 2.80 8.20 Device Type: Description: 1-100PPP-04 Humidity & Temperature Sensor SHTxx Part Order No. 1-100PPP-04 or Customer Number Date of Delivery: DD.MM.YYYY Order Code: 45CCCC / 0 Figure 21: Tape configuration and unit orientation within tape, dimensions in mm (1mm = 0.039inch). The leader tape is at the right side of the figure while the trailer tape is to the left (direction of unreeling). Figure 20: Second label on reel: For Device Type and Part Order Number please refer to Table 12, Delivery Date (also Date Code) is date of packaging of sensors (DD = day, MM = month, YYYY = year), CCCC = Sensirion order number. www.sensirion.com Version 4.0 – July 2008 10/11 Datasheet SHT1x Revision History Date March 2007 August 2007 July 2008 Version 3.0 3.01 4.0 Page(s) 1 – 10 1 – 10 1 – 10 Changes Data sheet valid for SHTxx-V4 and SHTxx-V3 Electrical characteristics added, measurement time corrected New release, rework of datasheet Important Notices 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 product, 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 defend, 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 sensitive 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 SENSIRION’s published specifications of the product. 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 fourteen (14) days after their appearance; • such defects shall be found, to SENSIRION’s reasonable satisfaction, to have arisen from SENSIRION’s faulty design, material, or workmanship; • the defective product shall be returned to SENSIRION’s factory at the Buyer’s 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 recommended 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 LIMITATION, 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 of 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 application 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 for each customer’s applications by customer’s 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© 2007, SENSIRION. CMOSens® is a trademark of Sensirion All rights reserved Headquarter and Sales Offices Headquarter SENSIRION AG Laubisruetistr. 50 CH-8712 Staefa ZH Switzerland Sales Office USA: Phone: + 41 (0)44 306 40 00 Fax: + 41 (0)44 306 40 30 info@sensirion.com http://www.sensirion.com/ Sales Office Korea: SENSIRION KOREA Co. Ltd. #1414, Anyang Construction Tower B/D, 1112-1, Bisan-dong, Anyang-city Gyeonggi-Province South Korea SENSIRION Inc. 2801 Townsgate Rd., Suite 240 Westlake Village, CA 91361 USA Phone: 805 409 4900 Fax: 805 435 0467 michael.karst@sensirion.com http://www.sensirion.com/ Sales Office Japan: Phone: 031 440 9925~27 Fax: 031 440 9927 info@sensirion.co.kr http://www.sensirion.co.kr SENSIRION JAPAN Co. Ltd. Postal Code: 108-0074 Shinagawa Station Bldg. 7F, 4-23-5, Takanawa, Minato-ku Tokyo, Japan Phone: 03 3444 4940 Fax: 03 3444 4939 info@sensirion.co.jp http://www.sensirion.co.jp Find your local representative at: http://www.sensirion.com/reps www.sensirion.com Version 4.0 – July 2008 11/11