The **SHT41-AD1B-R2** is a high-precision digital sensor manufactured by **Sensirion**. It is part of the 4th generation of humidity and temperature sensors (SHT4x series), designed for high-volume consumer and industrial applications. --- ### 1. Key Technical Specifications | Parameter | Specification | Details | | :--- | :--- | :--- | | **Interface** | I2C | Standard, Fast Mode, Fast Mode Plus | | **Supply Voltage (VDD)** | 1.08V to 3.6V | Ideal for battery-powered devices | | **Relative Humidity Range** | 0 to 100% RH | Accuracy: ±1.8% RH (typical) | | **Temperature Range** | -40°C to +125°C | Accuracy: ±0.2°C (typical) | | **Energy Consumption** | 0.4 µA (Avg) | At 1 measurement per second | | **Package Type** | DFN 4-pin | 1.5 x 1.5 x 0.5 mm size | --- ### 2. Functional Components The sensor integrates several electronic sub-systems into a single CMOS chip: #### A. Sensing Elements * **RH Sensor:** A capacitive sensing element that utilizes a polymer dielectric to detect changes in humidity. * **Temperature Sensor:** A high-precision bandgap temperature sensor. #### B. Signal Processing & ASIC * **ADC:** An onboard Analog-to-Digital Converter translates the raw analog capacitance/voltage into digital data. * **Calibration Memory:** Each sensor is factory-calibrated. Calibration coefficients are stored on-chip and applied automatically. * **Heater:** Includes an integrated power-programmable heater used to remove condensation or verify sensor integrity in harsh environments. #### C. Interface (I2C) The **AD1B** suffix specifically defines the I2C address and behavior: * **I2C Address:** 0x44 (7-bit). * **Communication:** Supports clock stretching and high-speed data transfer. --- ### 3. Pin Configuration (DFN-4) | Pin # | Name | Description | | :--- | :--- | :--- | | 1 | **SDA** | Serial Data (Bidirectional) | | 2 | **SCL** | Serial Clock (Input) | | 3 | **VDD** | Supply Voltage | | 4 | **VSS** | Ground (GND) | --- ### 4. Implementation Example (Pseudocode) To interface with the SHT41, you typically send a command byte to trigger a measurement. ```python import smbus import time # I2C Address for SHT41-AD1B I2C_ADDR = 0x44 # Command: High Precision Measurement CMD_MEASURE = 0xFD bus = smbus.SMBus(1) # Trigger measurement bus.write_byte(I2C_ADDR, CMD_MEASURE) time.sleep(0.01) # Wait for conversion # Read 6 bytes: [Temp MSB, Temp LSB, Temp CRC, RH MSB, RH LSB, RH CRC] data = bus.read_i2c_block_data(I2C_ADDR, 0, 6) # Conversion formulas t_ticks = data[0] << 8 | data[1] rh_ticks = data[3] << 8 | data[4] temp_c = -45 + 175 * (t_ticks / 65535.0) rh_pct = -6 + 125 * (rh_ticks / 65535.0) ``` ---