The **SHT45-AD1B-R3** is a high-precision digital humidity and temperature sensor manufactured by **Sensirion**. It is the ultra-high accuracy version of the SHT4x series, designed specifically for demanding industrial and medical applications. --- ### 1. Key Technical Specifications The "45" in the part number signifies it is the highest accuracy grade in the family. | Parameter | Specification | Notes | | :--- | :--- | :--- | | **Relative Humidity Accuracy** | ±1.0% RH | Typical (at 25°C) | | **Temperature Accuracy** | ±0.1°C | Typical (at 20°C to 60°C) | | **Operating Voltage** | 1.08V to 3.6V | Ideal for battery-powered devices | | **Interface** | I2C | Standard FM+ (up to 1 MHz) | | **Supply Current** | 0.4 µA (avg) / 80 µA (idle) | Ultra-low power consumption | | **Package Type** | DFN-4 | 1.5 x 1.5 x 0.5 mm footprint | --- ### 2. Electronic Architecture & Pinout The device is a CMOSens® chip, integrating the sensing elements, an analog-to-digital converter (ADC), and digital signal processing on a single silicon die. #### Pin Configuration (DFN-4 Package) | Pin # | Name | Description | | :--- | :--- | :--- | | 1 | **SDA** | Serial Data (I2C) | | 2 | **SCL** | Serial Clock (I2C) | | 3 | **VDD** | Supply Voltage | | 4 | **VSS** | Ground | --- ### 3. Critical Features * **Integrated Heater:** The chip includes an internal power-programmable heater. This is used to remove condensed water or "creep" from the sensor element in high-humidity environments. * **I2C Address:** The `AD1B` suffix typically refers to a specific I2C address (usually `0x44`), allowing multiple sensors to be used on the same bus if different variants are chosen. * **Fully Calibrated:** Every sensor is individually calibrated and tested, with the calibration data stored on the internal ROM. * **JEDEC JESD47 Qualification:** Ensures high reliability and long-term stability. --- ### 4. Implementation Circuit To integrate the SHT45 into a circuit, minimal external components are required. ```markdown VCC (1.8V - 3.3V) | +-------[ 100nF Cap ]-------+ | | +-------[ 10k Pull-up ]-----+--- SDA (Pin 1) | | +-------[ 10k Pull-up ]-----+--- SCL (Pin 2) | GND (Pin 4) ``` --- ### 5. Part Number Breakdown: SHT45-AD1B-R3 * **SHT45:** High-accuracy series (±1.0% RH, ±0.1°C). * **AD1B:** I2C interface variant (Standard address 0x44). * **R3:** Packaging format (Tape & Reel, 2,500 - 10,000 pcs per reel). ---