SEK-SHT40-AD1B-SENSORS

SHT4x 4th Generation, High-Accuracy, Ultra-Low-Power, 16-bit Relative Humidity and Temperature Sensor Platform Features  Relative humidity accuracy: up to ±1.5 %RH  Operating range: 0…100 %RH, -40…125 °C  Temperature accuracy: up to ±0.1 °C  Fully functional in condensing environment  Supply voltage: 1.08 V … 3.6 V  Variable power heater  Average current: 0.4 µA (at meas. rate 1 Hz)  NIST traceability  Idle current: 80 nA  JEDEC JESD47 qualification  I2C fast mode plus, CRC checksum  Mature technology from global market leader General Description SHT4x is a digital sensor platform for measuring relative humidity and temperature at different accuracy classes. The I2C interface provides several preconfigured I2C addresses and maintains an ultra-low power budget. The power-trimmed internal heater can be used at three heating levels thus enabling sensor operation in demanding environments. The four-pin dual-flat-no-leads package is suitable for surface mount technology (SMT) processing. Device Overview Functional Block Diagram Products Details SHT40-AD1B base RH&T accur., 0x44 I2C addr. SHT40-BD1B base RH&T accur., 0x45 I2C addr. SHT41-AD1B Intermed. RH&T accur., 0x44 I2C addr. SHT45-AD1B ±1.5 %RH, ±0.1°C accur., 0x44 I2C addr. Full product list on page 14 www.sensirion.com / D1 Version 1 – October 2020 1/16 Contents Features ........................................................................................................................................................................ 1 General Description ................................................................................................................................................... 1 Device Overview ......................................................................................................................................................... 1 Functional Block Diagram ........................................................................................................................................ 1 1 Quick Start – Hello World ..................................................................................................................................... 3 2 Humidity and Temperature Sensor Specifications ....................................................................................... 4 2.1 Relative Humidity ............................................................................................................................................4 2.2 Temperature .....................................................................................................................................................5 2.3 Recommended Operating Conditions ......................................................................................................6 3 Electrical Specifications ........................................................................................................................................ 6 3.1 Electrical Characteristics ..............................................................................................................................7 3.2 Timings ...............................................................................................................................................................7 3.3 Absolute Maximum Ratings .........................................................................................................................8 4 Sensor Operation .................................................................................................................................................... 8 4.1 I2C communication.........................................................................................................................................8 4.2 Data type & length ..........................................................................................................................................9 4.3 Checksum Calculation...................................................................................................................................9 4.4 Command Overview ....................................................................................................................................10 4.5 Conversion of Signal Output .....................................................................................................................10 4.6 Serial number .................................................................................................................................................10 4.7 Reset.................................................................................................................................................................10 4.8 Heater Operation...........................................................................................................................................11 5 Physical Specification .......................................................................................................................................... 11 5.1 Package Description ....................................................................................................................................11 5.2 Package Outline ............................................................................................................................................12 5.3 Land Pattern ...................................................................................................................................................12 5.4 Pin Assignment & Laser Marking .............................................................................................................13 5.5 Thermal Information .....................................................................................................................................13 6 Quality and Material Contents........................................................................................................................... 13 7 Tape and Reel Packaging .................................................................................................................................. 13 8 Product Name Nomenclature ............................................................................................................................ 14 9 Ordering Information ............................................................................................................................................ 15 10 Bibliography.......................................................................................................................................................... 15 11 Revision History .................................................................................................................................................. 15 www.sensirion.com / D1 Version 1 – October 2020 2/16 1 Quick Start – Hello World A typical application circuit for SHT4x is shown on the left-hand side of Figure 1. After reaching the minimal supply voltage and allowing for the maximal power-up time of 1 ms the sensor is ready for I2C communication. The quickest way to measure humidity and temperature is pseudo-coded on the right-hand side of Figure 1. Together with the conversion formulae given in equations ( 1 ), ( 2 ), and ( 3 ), the digital signals can be translated into relative humidity and temperature readings. Typical application circuit Pseudo code i2c_write(i2c_addr=0x44, tx_bytes=[0xFD]) wait_seconds(0.01) rx_bytes = i2c_read(i2c_addr=0x44, number_of_bytes=6) t_ticks = rx_bytes[0] * 256 + rx_bytes[1] rh_ticks = rx_bytes[3] * 256 + rx_bytes[4] t_degC = -45 + 175 * t_ticks/65535 rh_pRH = -6 + 125 * rh_ticks/65535 if (rh_pRH > 100): rh_pRH = 100 if (rh_pRH < 0): rh_pRH = 0 Figure 1: Typical application circuit (left) and pseudo code (right) for easy starting. For details on the signal cropping in the last four lines see section 4.5. Find code resources and embedded drivers on: https://github.com/Sensirion/embeddedsht/releases CAD files can be downloaded from SnapEDA: https://www.snapeda.com/parts/SHT40-AD1BR3/Sensirion/view-part/ www.sensirion.com / D1 Version 1 – October 2020 3/16 2 Humidity and Temperature Sensor Specifications 2.1 Relative Humidity Parameter Conditions typ. SHT40 RH accuracy1 Value 1.8 see Figure 2 max. typ. SHT41 RH accuracy1 1.8 See Figure 3 max. typ. SHT45 RH accuracy1 1.5 tbd 0.08 0.15 0.25 0.01 max. high medium low - Repeatability2 Resolution3 Hysteresis range4 1 0 to 100 6 1.62 V: fast mode plus - - 340 VDD < 1.62V, Rpullup > 820 Ω VDD = 1.62V … 2.0V, Rpullup > 390 Ω VDD > 2.0V, Rpullup > 390 Ω - Average current µA consumption while sensor is measuring Aver. current consumpt. µA (contin. operation with one meas. per second) Aver. power consumpt. µW (contin. operation with one meas. per second) V 0.7* VDD 820 Rp Pull up resistors Comments - - VDD V - - Ω - - Ω - V - V - 0.2* VDD 0.2* VDD Capac. bus load can be determined from Cb < trise /(0.8473*Rp). Rise times are trise = 300 ns for fast pF mode and t = 120 ns rise for fast mode plus Table 3: Electrical specifications. 3.2 Timings Max. values are measured at -40°C and 1.08 V supply voltage (based on characterization). www.sensirion.com / D1 Version 1 – October 2020 7/16 Parameter Symbol Conditions Min. Typ. Power-up time tPU After hard reset, VDD ≥ VPOR - 0.3 1 Soft reset time tSR After soft reset - - 1 Waiting time tW 1 - - - 1.3 1.7 - 3.7 4.5 - 6.9 8.2 Long pulse 0.9 1 1.1 s Short pulse 0.09 0.1 0.11 s tMEAS,l Measurement duration tMEAS,m tMEAS,h Heater-on duration between I2C commands Low repeatability Med. repeatability High repeatability Max. Units Comments Time between VDD reaching VPOR and ms sensor entering idle state Time between ACK of soft reset command and ms sensor entering idle state. Also valid for I2C general call reset. minimal waiting time for ms I2C communication ms The three repeatability modes differ with ms respect to measurement duration, noise level and energy consumption ms tHeater After that time the heater is automatically switched off After that time the heater is automatically switched off Table 4 System timing specifications. 3.3 Absolute Maximum Ratings Stress levels beyond those listed in Table 5 may cause permanent damage or affect the reliability of the device. These are stress ratings only and functional operation of the device at these conditions is not guaranteed. Ratings are only tested each at a time. Parameter Max. voltage on any pin Operating temperature range Storage temperature range10 ESD HBM ESD CDM Latch up, JESD78 Class II, 125°C Rating VSS - 0.3 V … VDD + 0.3 V -40 °C … 125 °C -40 °C …150 °C 2 kV 500 V +-100 mA Table 5: Absolute maximum ratings. 4 Sensor Operation 4.1 I2C communication I2C communication is based on NXP’s I2C-bus specification and user manual UM10204, Rev.6, 4 April 2014. Supported I2C modes are standard, fast mode, and fast mode plus. Data is transferred in multiples of 16-bit words and 8-bit check sum (cyclic redundancy check = CRC). All transfers must begin with a start condition (S) and terminate with a stop condition (P). To finish a read transfer, send not acknowledge (NACK) and stop condition (P). Addressing a specific slave device is done by sending its 7-bit I2C address followed by an eighth bit, denoting the communication 10 The recommended storage temperature range is 10-50°C. Please consult the document “SHTxx Handling Instructions” for more information. www.sensirion.com / D1 Version 1 – October 2020 8/16 direction: “zero” indicates transmission to the slave, i.e. “write”, a “one” indicates a “read” request. Schematics of the I2C transfer types are sketched in Figure 8. Figure 8: I2C transfer types: First a write header is sent to the I2C slave, followed by a command, for example “measure RH&T with highest precision”. After the measurement is finished the read request directed to this I2C slave will be acknowledged and transmission of data will be started by the slave. 4.2 Data type & length I2C bus operates with 8-bit data packages. Information from the sensor to the master has a checksum after every second 8-bit data package. Humidity and temperature data will always be transmitted in the following way: The first value is the temperature signal (2 * 8-bit data + 8-bit CRC), the second is the humidity signal (2 * 8-bit data + 8-bit CRC). 4.3 Checksum Calculation For read transfers each 16-bit data is followed by a checksum with the following properties Property Name Message Length Polynomial Initialization Value CRC-8 16-bit 8 0x31 (x + x5 + x4 +1) 0xFF Reflect Input/Output Final XOR Examples false/false 0x00 CRC(0xBEEF) = 0x92 Table 6 Data check sum properties. The master may abort a read transfer after the 16-bit data, if it does not require a checksum. www.sensirion.com / D1 Version 1 – October 2020 9/16 4.4 Command Overview Command bin hex 1111 1101 FD Response length incl. CRC (bytes) 6 1111 0110 F6 6 measure T & RH with medium precision (medium repeatability) 1110 0000 E0 6 measure T & RH with lowest precision (low repeatability) 1000 1001 89 6 read serial 1001 0100 94 - soft reset 0011 1001 39 6 0011 0010 32 6 0010 1111 2F 6 0010 0100 24 6 0001 1110 1E 6 0001 0101 15 6 activate highest heater power & high precis. meas. (typ. 200mW @ 3.3V) for 1s activate highest heater power & high precis. meas. (typ. 200mW @ 3.3V) for 0.1s activate medium heater power & high precis. meas. (typ. 110mW @ 3.3V) for 1s activate medium heater power & high precis. meas. (typ. 110mW @ 3.3V) for 0.1s activate lowest heater power & high precis. meas. (typ. 20mW @ 3.3V) for 1s activate lowest heater power & high precis. meas. (typ. 20mW @ 3.3V) for 0.1s Description measure T & RH with high precision (high repeatability) Table 7 Overview of I2C commands. 4.5 Conversion of Signal Output The digital sensor signals correspond to following humidity and temperature values: 𝑆𝑅𝐻 𝑅𝐻 = (−6 + 125 ∙ 16 ) %RH 2 −1 𝑆𝑇 𝑇 = (−45 + 175 ∙ 16 ) °C 2 −1 𝑆𝑇 𝑇 = (−49 + 315 ∙ 16 ) °F 2 −1 (1) (2) (3) N.B.: The RH conversion formula (1) allows values to be reported which are outside of the range of 0 %RH … 100 %RH. Relative humidity values which are smaller than 0 %RH and larger than 100 %RH are non-physical, however these “uncropped” values might be found beneficial in some cases (e.g. when the distribution of the sensors at the measurement boundaries are of interest). For all users who don’t want to engage in evaluation of these non-physical values, cropping of the RH signal to the range of 0 %RH … 100 %RH is advised. 4.6 Serial number Each and every single sensor has a unique serial number, that is assigned by Sensirion during production. It is stored in the one-time-programmable memory and cannot be manipulated after production. The serial number is accessible via I2C and is transmitted as two 16-bit words, each followed by an 8-bit CRC. 4.7 Reset A reset of the sensor can be achieved in three ways:  Soft reset: send the reset command described in Table 7.  I2C general call: all devices on I2C bus are reset by sending the command 0x06 to the I2C address 0x00.  Power down (incl. pulling SCL and SDA low) www.sensirion.com / D1 Version 1 – October 2020 10/16 4.8 Heater Operation The sensor incorporates an integrated on-chip heater which can be switched on by the set of commands given in Table 7. There are three different heating powers and two different heating times accessible to the user. After reception of a heater-on command, the sensor executes the following procedure: 1. The heater is enabled and the timer starts its count-down 2. On timer expiration a temperature and humidity measurement with the highest repeatability is started, the heater remains enabled 3. After the measurement is finished the heater is turned off 4. Temperature and humidity values are now available The maximum on-time of the heater commands is 1 second, in order to prevent overheating of the sensor by unintended usage of the heater. Thus, there is no dedicated command to turn off the heater. For extended heating periods it is required to send periodic heater-on commands, keeping in mind that the heater is designed for a maximal duty cycle of less than 5%. To obtain a fast increase in temperature the idle time between consecutive heating pulses shall be kept minimal. Possible Heater Use Cases There will be dedicated Sensirion application notes elaborating on various use cases of the heater. In general, the applications of the on-chip heater range around: 1. Removal of condensed / spray water on the sensor surface. Although condensed water is not a reliability / quality problem to the sensor, it will however make the sensor nonresponsive to RH changes in the air as long as there is liquid water on the surface. 2. Creep-free operation in high humid environments. Periodic heating pulses allow for creepfree high-humidity measurements for extended times. Important notes for operating the heater: 1. The heater is designed for a maximum duty cycle of 5%. 2. During operation of the heater, sensor specifications are not valid. 3. The temperature sensor can additionally be affected by the thermally induced mechanical stress, offsetting the temperature reading from the actual temperature. 4. The sensor’s temperature (base temperature + temperature increase from heater) must not exceed Tmax = 125 °C in order to have proper electrical functionality of the chip. If higher heating temperatures are desired, consecutive heating commands have to be sent to the sensor. The heater shall only be operated in ambient temperatures below 65°C else it could drive the sensor outside of its maximal operating temperature. 5 Physical Specification 5.1 Package Description SHT4x is provided in an open-cavity dual flat no lead (DFN) package. The humidity sensor opening is centered on the top side of the package. The sensor chip is made of silicon, hosted on a copper lead frame and overmolded by an epoxy-based mold compound. Exposed bottom side of the leadframe with the metallic contacts is Ni/Pd/Au coated, side walls are bare copper. Moisture sensitivity level (MSL) of 1 according to IPC/JEDEC J-STD-020 is achieved. It is recommended to process the sensors within one year after date of delivery. www.sensirion.com / D1 Version 1 – October 2020 11/16 5.2 Package Outline Figure 9 Dimensional drawing of SHT4x including package tolerances (units mm). 5.3 Land Pattern The land pattern is recommended to be designed according to the used PCB and soldering process together with the physical outer dimensions of the sensor. For reference, the land pattern used with Sensirion’s PCBs and soldering processes is given in Figure 10. Soldering of the central die pad is optional. Sensirion recommends to not solder the central die pad because the sensor can reach higher temperatures upon heater activation. Figure 10: Recommended land pattern (in mm). Details can vary and depend on used PCBs and solder processes. There shall be no copper under the sensor other than at the pin pads. www.sensirion.com / D1 Version 1 – October 2020 12/16 5.4 Pin Assignment & Laser Marking Pin 1 2 3 4 Name SDA SCL VDD VSS Comments Serial data, bidirectional Serial clock, unidirectional input Supply voltage Ground Figure 11 Pin assignment (transparent top view). Dashed lines are only visible if sensor is viewed from below. The die pad is not directly connected to any pin. The laser marking consists of two lines, indicated in Figure 11. In the first line a filled circle serves as pin-1 indicator and is followed by “SH4”. The last character will indicate the accuracy class of this product (here “x” serves as place holder). In the second line, the first three characters specify the product characteristics according to positions 7,8 and 9 of Table 9. The second three characters serve as internal batch tracking code. 5.5 Thermal Information Symbol Description 𝑅𝜃𝐽𝐴 Junction-to-ambient thermal resistance Junction-to-case thermal resistance Junction-to-board thermal resistance Junction-to-board characterization param. Junction-to-top characterization param. 𝑅𝜃𝐽𝐶 𝑅𝜃𝐽𝐵 Ψ𝐽𝐵 Ψ𝐽𝑇 Heater off, die pad soldered (K/W) Heater on, die pad soldered (K/W) Heater off, die pad not soldered (K/W) Heater on, die pad not soldered (K/W) 246 308 297 357 189 255 191 257 159 225 193 258 159 223 191 254 38 105 44 112 Table 8 Typical values for thermal metrics. In the “heater on” columns a heater power of 200 mW was assumed. Soldering of the die pad is not recommended, therefore the two right hand side columns are bold. Values are based on simulation. 6 Quality and Material Contents Qualification of SHT4x is performed based on the JEDEC JESD47 qualification test method. Qualification pending. The device is fully RoHS and WEEE compliant, e.g. free of Pb, Cd, and Hg. For general remarks of best practice in processing humidity sensor please refer to the handling instructions (Sensirion, 2020). 7 Tape and Reel Packaging All specifications for the tape and reel packaging can be found on Figure 12. Reel diameters are 13 inch and 8 inch for the 10k and the 2.5k packaging sizes, respectively. www.sensirion.com / D1 Version 1 – October 2020 13/16 Figure 12: Tape and reel specifications including sensor orientation in pocket (see indication of two sensors on the right side of the tape). 8 Product Name Nomenclature position 1 2 3 4 5 6 7 8 9 10 11 12 13 value(s) S H T 4 0 1 5 A B D 1 B R 2 3 explanation Sensirion Humidity Signal Temperature Signal Fourth product generation Base accuracy Intermediate accuracy Best accuracy delimiter I2C interface with 0x44 address I2C interface with 0x45 address DFN package reserved blank package without membrane delimiter Tape on reel packaging Packaging article contains 2’500 pieces Packaging article contains 10’000 pieces Table 9 SHT4x product name nomenclature. www.sensirion.com / D1 Version 1 – October 2020 14/16 9 Ordering Information Material Description SHT40-AD1B-R2 SHT40-AD1B-R3 SHT40-BD1B-R2 SHT40-BD1B-R3 Material Number 3.000.465 3.000.353 tbd tbd SHT41-AD1B-R2 3.000.466 SHT41-AD1B-R3 tbd SHT45-AD1B-R2 tbd SHT45-AD1B-R3 tbd Details base RH&T accuracy, 0x44 I2C addr. base RH&T accuracy, 0x44 I2C addr. base RH&T accuracy, 0x45 I2C addr. base RH&T accuracy, 0x45 I2C addr. Available 2021 intermed. RH&T accuracy, 0x44 I2C addr. Available 2021 intermed. RH&T accuracy, 0x44 I2C addr. Available 2021 ±1.5%RH, ±0.1°C acc., 0x44 I2C addr. Available 2021 ±1.5%RH, ±0.1°C acc, 0x44 I2C addr. Quantity (pcs) 2’500 10’000 2’500 10’000 2’500 10’000 2’500 10’000 Table 10 SHT4x ordering options. 10 Bibliography Sensirion. (2020). Handling Instructions for Humidity Sensors. Retrieved from www.sensirion.com 11 Revision History Date October 2020 www.sensirion.com / D1 Version 1 Page(s) all Version 1 – October 2020 Changes Initial release 15/16 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 © 2020, by SENSIRION. CMOSens® is a trademark of Sensirion. All rights reserved Headquarters and Subsidiaries Sensirion AG Laubisruetistr. 50 CH-8712 Staefa ZH Switzerland Sensirion Inc., USA phone: +1 312 690 5858 info-us@sensirion.com www.sensirion.com Sensirion Korea Co. Ltd. phone: +82 31 337 7700~3 info-kr@sensirion.com www.sensirion.com/kr phone: +41 44 306 40 00 fax: +41 44 306 40 30 info@sensirion.com www.sensirion.com Sensirion Japan Co. Ltd. phone: +81 3 3444 4940 info-jp@sensirion.com www.sensirion.com/jp Sensirion China Co. Ltd. phone: +86 755 8252 1501 info-cn@sensirion.com www.sensirion.com/cn Sensirion Taiwan Co. Ltd phone: +886 3 5506701 info@sensirion.com www.sensirion.com www.sensirion.com / D1 To find your local representative, please visit www.sensirion.com/distributors Version 1 – October 2020 16/16