0.2 0.4 3.0 Datasheet SHT21S Humidity and Temperature Sensor IC Fully calibrated SDM interface convertible to analog output Low power consumption Excellent long term stability DFN type package reflow solderable Product Summary SDM signal is a pulse sequence that with a low pass filter The SHT21 humidity and temperature sensor of Sensirion may be converted into analog voltage output. The data has become an industry standard in terms of form factor signal is provided on SDA line. Pulling SCL high or low and intelligence: Embedded in a reflow solderable Dual allows for switching between humidity and temperature, Flat No leads (DFN) package of 3 x 3mm foot print and respectively. The sensor measures the physical values 1.1mm height it provides calibrated, linearized sensor twice per second. signals in analog Sigma Delta Modulated (SDM) format. Every sensor is individually calibrated and tested. Lot The SHT2x sensors contain a capacitive type humidity identification is printed on the sensor. sensor, a band gap temperature sensor and specialized analog and digital integrated circuit all on a single With this set of features and the proven reliability and CMOSens chip. This yields in an unmatched sensor long-term stability, the SHT2x sensors offer an performance in terms of accuracy and stability as well as outstanding performance-to-price ratio. For testing SHT2x minimal power consumption. two evaluation kits EK-H4 and EK-H5 are available. Dimensions Sensor Chip 3.0 SHT21S feature a generation 4C CMOSens chip. 0.3 typ Besides the capacitive relative humidity sensor and the band gap temperature sensor, the chip contains an amplifier, A/D converter, OTP memory and a digital processing unit. 1.4 max 2.2 1.1 Material Contents While the sensor itself is made of Silicon the sensors Bottom housing consists of a plated Cu lead-frame and green View 0.4 0.3 epoxy-based mold compound. The device is fully RoHS NC VDD SCL and WEEE compliant, e.g. free of Pb, Cd and Hg. 2.4 Additional Information Additional information such as Application Notes is VSS SDA 1.0 1.0 NC available from the web page www.sensirion.com/sht21. For more information please contact Sensirion via Figure 1: Drawing of SHT21S sensor package, dimensions info sensirion.com. are given in mm (1mm = 0.039inch), tolerances are 0.1mm. The die pad (center pad) is internally connected to VSS. The NC pads must be left floating. Numbering of E/O pads starts at lower right corner (indicated by notch in die pad) and goes clockwise (compare Table 2). www.sensirion.com Version 4 May 2014 1/10 0.75 1.5 2.4 max SHT21 D0AC4 Sensor Performance 123 456 Relative Humidity Temperature Parameter Condition Value Units Parameter Condition Value Units Resolution 12 bit 0.04 %RH Resolution 14 bit 0.01 C typ %RH typ C 2.0 0.3 Accuracy Accuracy 1 1 tolerance tolerance max see Figure 2 %RH max see Figure 3 C Repeatability 0.1 %RH Repeatability 0.1 C 3 Hysteresis %RH Operating Range extended -40 to 125 C 1 6 Nonlinearity <0.1 %RH Response Time 5 to 30 s 63% 2 7 Long Term Drift Typ. < 0.02 C/yr Response time 63% 8 s 3 Operating Range extended 0 to 100 %RH 4 Long Term Drift Typ. < 0.25 %RH/yr RH(%RH) T (C) 10 2.0 maximum accuracy maximum accuracy 8 typical accuracy typical accuracy 1.5 6 1.0 4 0.5 2 0.0 0 -40 -20 0 20 40 60 80 100 120 0 10 20 30 40 50 60 70 80 90 100 Relative Humidity (%RH) Temperature (C) Figure 2 Typical and maximal tolerance at 25C for relative Figure 3 Typical and maximal temperature accuracy tolerance. humidity. For extensive information see Users Guide, Sect. 1.2. For electronic impacts on accuracy please consult Sect. 5.3. For electronic impacts on accuracy please consult Sect. 5.3. Packaging Information Electrical Specification Sensor Type Packaging Quantity Order Number Parameter Condition min typ max Units Tape & Reel 400 1-100718-01 Supply Voltage, VDD 2.1 3.0 3.6 V SHT21S Tape & Reel 1500 1-100697-01 5 Supply Current, IDD 160 A Tape & Reel 5000 1-100696-01 5 Power Dissipation 0.48 mW Measurement 2 Hz Frequency Switch RH/T on SDA SCL up RH SCL down T Table 1 Electrical specification. For absolute maximum This datasheet is subject to change and may be amended values see Chapter 4.1 of Users Guide. without prior notice. 4 Typical value for operation in normal RH/T operating range. Max. value is < 0.5 1 %RH/y. Value may be higher in environments with vaporized solvents, out- Accuracies are tested at Outgoing Quality Control at 25C and 3.0V. Values gassing tapes, adhesives, packaging materials, etc. For more details please exclude hysteresis and long term drift and are applicable to non-condensing refer to Handling Instructions. environments only. 5 2 Values of Supply Current and Power Dissipation are based upon fixed VDD = Time for achieving 63% of a step function, valid at 25C and 1 m/s airflow. 3.0V and T = 25C applying a low pass filter as proposed in Sect. 5.3. 3 Normal operating range: 0-80%RH, beyond this limit sensor may read a 6 Response time depends on heat conductivity of sensor substrate. reversible offset with slow kinetics (+3%RH after 60h at humidity >80%RH). For 7 Max. value is < 0.04C/y. more details please see Section 1.1 of the Users Guide. www.sensirion.com Version 4 May 2014 2/10