The **W5TS-243-R/Q** is a high-precision, automotive-grade non-contact infrared (IR) temperature sensor module manufactured by Omron. It is specifically designed for integration into HVAC systems and cabin monitoring within vehicles. --- ## 1. Technical Specifications The following table outlines the primary electronic and physical characteristics of the module: | Parameter | Specification | | :--- | :--- | | **Supply Voltage (Vcc)** | 4.5V to 5.5V DC | | **Current Consumption** | Max 10mA (Active mode) | | **Interface** | I2C (Inter-Integrated Circuit) | | **Object Temp Range** | -40°C to +125°C | | **Operating Temp Range** | -40°C to +85°C | | **Resolution** | 0.02°C | | **Accuracy** | ±0.5°C to ±2.0°C (Depends on ambient temp) | | **Housing** | Integrated lens and metal case for EMI shielding | --- ## 2. Key Electronic Components The module is an "All-in-One" integrated system, containing the following internal sub-components: ### A. Thermopile Sensor Element * **Function:** Converts incoming thermal radiation into a micro-voltage signal. * **Material:** Uses a high-sensitivity silicon-based thermopile membrane. ### B. Signal Conditioning Circuit (ASIC) * **Low Noise Amplifier (LNA):** Since the thermopile output is very small (μV range), an internal LNA boosts the signal. * **Analog-to-Digital Converter (ADC):** A high-resolution ADC (typically 16-bit or higher) converts the analog thermal signal into digital data. * **Internal Temperature Reference:** Includes a built-in thermistor to measure the sensor's own "ambient" temperature, which is necessary for calculating the target's absolute temperature (cold-junction compensation). ### C. Digital Processing & Memory * **EEPROM:** Stores factory calibration constants specific to that individual unit. * **DSP (Digital Signal Processor):** Performs the complex mathematical conversion from raw voltage to temperature values using the Stefan-Boltzmann law. --- ## 3. Communication Protocol (I2C) The W5TS series communicates via a standard I2C bus. Below is a simplified representation of how a microcontroller interacts with the sensor: ```c // Example Pseudocode for reading temperature void read_temp() { I2C_Start(); I2C_Write(W5TS_ADDRESS); // Sensor Address I2C_Write(REG_TEMP_OBJECT); // Register for Object Temperature I2C_Restart(); I2C_Read(High_Byte); // Data MSB I2C_Read(Low_Byte); // Data LSB I2C_Stop(); // Calculate actual temperature float temp = ((High_Byte << 8) | Low_Byte) * 0.02; } ``` --- ## 4. Distinguishing Features (R/Q Suffix) The suffix in the part number denotes specific automotive qualifications and packaging: * **Q:** Indicates "Automotive Grade" quality assurance, often complying with AEC-Q100 standards. * **R:** Refers to the specific Field of View (FoV) or orientation—this model typically features a wide-angle lens suitable for monitoring large areas like a car seat. * **EMC Protection:** The electronics include internal filters to prevent interference from vehicle ignition systems and mobile radio signals.