DatasheetHTE301 Digital Humidity and Temperature Sensor

HTE301 Digital Humidity and Temperature Sensor The HTE301 is the next generation of the digital RH/T series HTEx01. The sensor provides an accuracy of up to 1.8 %RH incl. hysteresis, a constant current heater and integrated sensor coating. With a 16-bit unsigned integer value and a different pin assignment compared to HTE501, the HTE301 allows an easy upgrade for your existing application with minimal integration effort. Furthermore the sensor covers a wide application range from -40 to +125 °C and 0 to 100 %RH. Therefore, the HTE301 offers a versatile measuring device for demanding tasks. With...

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Table 1: List of HTE301 specific acronyms v1.3 / Modification rights reserved | 5

1 Pin Configuration Top view Bottom view Thermal pad internally connected to GND 1) Soldering of the thermal pad is optional. However, the soldering is recommended. Do not use the heat conduction pad on the PCB for heat dissipation but purely as a mounting surface, otherwise heating energy is lost. Figure 2: Typical application schematic v1.3 / Modification rights reserved | 6

3 Specification 3.1 Relative Humidity Sensor Table 4: Temperature sensor parameters 1) In the periodic mode the humidity hysteresis is included. See also chapter 3.3 Recommended Operating Conditions. 2) In the periodic mode the humidity accuracy is within the hysteresis. In the single shot measurement, the humidity hysteresis must be added to the given humidity accuracy to obtain the overall accuracy. 3) The detailed definition of “typ.” and “max.” is given in the document Sensor Specification Accuracy, available at www.epluse.com/hte301. 4) Default resolution is 13 bit temperature / 13 bit humidity....

3.3 Recommended Operating Conditions The sensor shows best performance when operated within the normal operating conditions (dark green area in Figure 5). This means 20...80 %RH, temperature >0 °C and dew point temperature <60 °C. Exposure conditions outside this “Normal operating condition” for a long time, especially at high humidity >80 %RH may cause a temporary humidity gain error. If the sensor is brought back to normal operating conditions, the initial values will recover. Applications with high humidity at high temperatures will result in slower recovery. Reconditioning procedures can...

4.1 Absolute Maximum Ratings 1) Without I2C communication and when not measuring. 2) The chip temperature must not exceed 125°C with heater on. Table 6: General operation v1.3 / Modification rights reserved | 9

Table 9: General timing Subsequently, the typical measurement time with high repeatability is: v1.3 / Modification rights reserved | 10

Table 10: Measurement resolution 5.1 Pin Configuration, Assignment and Description Please refer to chapter 1. The supply pins must be equipped with a bypass ceramic capacitor of at least 100 nF. When using the constant current heater, a current change in the heater must not lead to a voltage drop below the minimum VDD value (refer to Table 6). This means the bypass capacitor needs to be dimensioned sufficiently large so that the voltage controller is supplied adequately. Sensor Power-up As soon as VDD exceeds the POR voltage VPORP, the device gets initialized. After tPWRU, the initialization...

The sensor's I2C base address is 0x44 (without R/ bit). Pins A1...A2 define the I2C base address. The ALERT pin indicates low when the temperature and relative humidity are in the range: If any of temperature or relative humidity measurement values goes outside this range the ALERT pin will output high, which will remain high as long as the corresponding value will go back inside the given temperature or humidity range including the hysteresis as shown in the plots below. www.epluse.com v1.3 / Modification rights reserved | 12

As soon as the falling edge on the reset pin is in the logic “0” blue area (low signal), as shown in the diagram below, the device goes into the reset and remains in this state as along as the voltage on the reset pin remains in the logic “0” area. In particular, during this phase, the device is in the cycle of being powered-up and reset immediately after power-up, thus the current consumption corresponds to the power-up current, approximately 1 mA. During the reset time, the device will not respond to any request on the I2C interface and set all digital outputs into a tristate mode. As soon...

6 Sensor Communication 6.1 Command Overview 6.2 Measured Data Format v1.3 / Modification rights reserved | 14

Measurement Modes There are two different operation modes to communicate with the sensor: 1.shotSingle Single mode Shot Measurement G:\Produkte\HTEx01\501\Archive_Diagrams&Drawings\PWRup_HIpin_Modi tPWRU tMEAS Time depends on COMMAND Time depends on COMMAND time time tMEAS IDLE MODE IDLE MODE COMMAND COMMAND Break Break Measurement Measurement Measurement Measurement COMMAND COMMAND Fetch Measurement Fetch Measurement Measurement Measurement COMMAND COMMAND Periodic Mode Periodic Mode Single Measurement Single Measurement at powerat uppower up optional COMMAND optional COMMAND Fetch Measurement...

MEASUREMENT ONGOING tMEAS N P single shot 1 10: Start Figure 1 Without clock stretching MEASUREMENT FINISHED 16 BIT COMMAND measurement readout 16 BIT COMMAND Without clock stretching W FREE A A FOR OTHER CMD MSBBUS MEMBERS I2C-ADDRESS SCL S 0 0 0 SCL FREE FOR OTHER BUS MEMBERS A 4 3LSB 2 1 0 7 6 5 CMD W A A Figure Clock stretching during measurement CMD MSB I2C-ADDRESS S 11: CMD LSB MEASUREMENT ONGOING 0 0 0 16 BIT COMMAND MEASUREMENT FINISHED MEASUREMENT ONGOING tMEAS In case a command with clock stretching enabled has been issued, the slave holds SCL low until the calculation has been With...

Figure 14: Periodic measurement commands A periodic measurement command with a different measurement interval / resolution can be issued at any time, but the calculated value will be updated according the new settings earliest after a measurement with the new settings has been performed. Readout of calculation results in periodic measurement mode can be performed using the fetch command. This is similar to the readout of measurement results in single-shot mode, except that clock stretching is always disabled. The slave will answer with NACK if no measurement results are available. www.epluse.com...