EEH210 Digital humidity and temperature sensor Well proven humidity sensor element, state-of-the-art ASIC technology and highly accurate humidity and temperature adjustment represent the basis for outstanding performance of the digital humidity and temperature sensor EEH210. The proprietary E+E coating protects the sensor against dirt and corrosion, which leads to excellent long-term stability even in polluted environment. The measured values are available on the digital interfaces I2C, SPI, PWM and PDM.
3. SENSOR PERFORMANCE EEH210 is a relative humidity sensor and temperature sensor with band gap circuit, it contains oscillator, A/D convertor, regulator, D/A convertor, NVM, digital processing unit and calibration circuit. 3.1. Relative Humidity Sensor Parameter Resolution1) Accuracy Tolerance2) Repeatability Hysteresis Response Time3) Operating Range Long Term Drift5) Condition 12 bit 8 bit typ 12 bit extended4) min 0 typ 0.04 0.7 ±2.0 ±0.1 ±1 max 10 100 0.
Figure 4: Typical and maximal tolerance for temperature 3.3. Operating Range The standard working range with regard to the humidity / temperature limits is shown by the dark gray area in Figure 5. The relative humidity signal may offset temporarily as a result of continuous exposure to conditions outside the dark gray region, especially at humidity > 80 % RH. If the sensor is brought back to the standard working range, the initial values will recover.
.2. Electrical specification The electrical characteristics such as power consumption, low and high level input and output voltages depend on the supply voltage. For proper communication with the sensor it is essential to make sure that signal design is strictly within the limits given in Table 4, Table 5 and Figure 6. Parameter Supply Voltage Current Dissipation PWM Freq. Measure Freq.
Parameter SPI clock cycle SPI clock frequency CS setup time CS hold time SDIO input setup time SDIO input hold time SDIO valid output time SDIO output hold time SDIO output disable time Symbol tc(SPC) fc(SPC) tsu(CSB) th(CSB) tsu(SI) th(SI) tv(SO) th(SO) tdis(SO) min 100 6 8 5 15 9 typ max 10 50 units ns MHz ns 50 Table 6: SPI - serial peripheral interface Figure 7: SPI slave timing diagram Measurement point are done at 0.3*VDD and 0.7*VDD, for both ports. 5. INTERFACE 5.1.
5.2. PIN Description Name NC Pin# 1 Type NC CSB 2 I / NC DA 3 O / NC VDD NC SDA / SDIO SCL / SPC SEL0 SEL1 VSS EP 4 5 6 7 8 9 10 P NC I/O I/O I I G Description No connect SPI mode: chip select input I2C,PWM, PDM mode: floating (NC) SPI mode: Data available output signal I2C, PWM, PDM mode: floating (NC) VDD Power Supply No connection I2C / SPI serial data signal & PWM / PDM Output I2C / SPI serial clock signal Mode Selection Mode Selection Ground Exposed Pad. EP is electrically connected to GND.
SEL[1:0] 00 01 10 11 SCL/SPC 0 1 0 1 I2C SPI SDA/SDIO PWM : T PWM : RH PDM : T PDM : RH DA Hi-z CSB Hi-z Hi-z Hi-z OUT 0 Table 8: SEL[1:0] pin setting condition table The SCL pin has to be fixed as ‘L’ or ‘H’ under PWM/PDM mode. 5.7. Startup sensor As a first step, the sensor is powered up to the chosen supply voltage VDD (typical 3.0 V). After power-up, the sensor needs at most 10 ms, while SCL is high, for reaching idle state, i.e.
6.2. Sending a Command After sending the Start condition, the subsequent I2C header consists of the 7 bit I2C device address ‘1000000’ and an SDA direction bit (Read R: ‘1’, Write W: ‘0’). The sensor indicates the proper reception of a byte by pulling the SDA pin low (ACK bit) after the falling edge of the 8th SCL clock. After the issue of a measurement command (‘11100011’ for temperature, ‘11100101’ for relative humidity), the MCU must wait for the measurement to complete.
In the examples given in Figure 9 and Figure 10 the sensor output is DRH = ‘0110’0011’0101’0000’. For the calculation of physical values Status Bits must be set to ‘0’ – see Chapter 5. The maximum duration for measurements depends on the type of measurement and resolution chosen – values are displayed in Table 9. Maximum values shall be chosen for the communication planning of the MCU. Figure 12: No Hold master communication sequence – grey blocks are controlled by EEH210.
OTP Reload is a safety feature and loads the entire OTP settings to the register before every measurement. This feature is disabled per default and is not recommended for use. Please use Soft Reset instead – it contains OTP Reload. bit #bits 7,0 2 6 1 5,4,3 2 1 3 1 1 Description / coding Measurement resolution RH Temp 00 12 bit 14 bit 01 8 bit 12 bit 10 10 bit 13 bit 11 11 bit 11 bit Status : End of battery1 0: VDD > 2.25V 1: VDD < 2.
RH = -6 + 125 ∙ DRH 216 In the example given in Figure 9 and Figure 10 the relative humidity results to be 42.5 % RH. RH = -6 + 125 ∙ 25424 = 42.492 ≈ 42.5 65536 The physical value RH given above corresponds to the relative humidity above liquid water according to World Meteorological Organization (WMO). For relative humidity above ice RHi the values need to be transformed from relative humidity above water RHw at temperature t. The equation is given in the following formular: RHi = RHW . exp ( ) βW .
7.2. SPI read Figure 16: SPI read protocol in 3-wires mode 7.3. Register mapping Name DEVICE ID ADC_RESOL CTRL_REG1 CTRL_REG2 CTRL_REG3 STATUS_REG HUMIDITY_OUT_L HUMIDITY_OUT_H TEMP_OUT_L TEMP_OUT_H Type R R/W R/W R/W R/W R Register address (hex) 0F 10 20 21 22 27 28 29 2A 2B R R R R Default (hex) 00 00 00 00 00 00 Output Output Output Output Table 13: Register mapping 7.4.
Address: 20h (R/W) Description: [7] PD: power down control ( 0: power down mode, 1 : active mode) [6:3] Reserved [2] BDU: block data update (0: continuous update, 1: output register not updated until MSB and LSB reading) [1:0] ODR1, ODR0: output data rate selection ODR1 0 0 1 1 ODR0 0 1 0 1 Humidity (Hz) Temperature (Hz) One shot 1 Hz 1 Hz 0.2 Hz 0.2 Hz 0.1 Hz 0.
The DA_EN bit enables the DA signal on pin 9. Normally inactive, the DA output signal becomes active on new data available: logical OR of the bits STATUS_REG[1] and STAUTS_REG[0] for humidity and temperature, respectively. The DA signal returns inactive after both HUMIDITY_OUT_H and TEMP_OUT_H registers are read.
TEMP_OUT_H 15 TOUT15 14 TOUT14 13 TOUT13 12 TOUT12 11 TOUT11 10 TOUT10 9 TOUT9 8 TOUT8 Table 25: TEMP_OUT_H Address: Description: 2Bh (R) Temperature data [7:0] TOUT15-TOUT8: Temperature data MSB 7.5.
The physical value RH given above corresponds to the relative humidity above liquid water according to World Meteorological Organization (WMO). The temperature T is calculated by inserting the ratio of tPW and tF into the following formula (result in °C): T = -46.85 + 175.72 ∙ tPW tF 8.2. PDM output PDM signal is a pulse sequence that with a low pass filter may be converted into analog voltage output. The data signal is provided on SDA line. By setting SEL[1:0] as ‘10’, the PDM output mode is selected.
Conversion of Signal Output After the low pass filter the sensor provides an output Voltage VSO which as a portion of VDD then is converted into a physical value. Resolution is set to 10 bit for relative humidity and 12 bit for temperature and cannot be changed. The sensor reading is linearized and hence it can be converted to a physical value by an easy linear equation.
9.3. Post reflow treatment We strongly recommend high humidity storage of the boards including the sensor packages after reflow soldering. 8hours at 70±5 °C, 75±5%RH or 24 hours at 80±10%RH (room temperature) is advisable. Calibration or testing should be done after a short further rest (>1 hour) at room conditions. 9.4. Handling information During the whole transportation process it should be avoided to expose the sensor to high concentrations of chemical solvents for longer time periods.
