The **MAH25TCD-R** is a high-performance, ultra-low power digital output thermal infrared (IR) sensor module. It is primarily designed for non-contact temperature measurement and human presence detection. Below is a detailed breakdown of its electronic components and specifications. --- ### 1. Key Technical Specifications The device operates on a thermopile principle, converting infrared radiation into an electrical signal, which is then processed digitally. | Parameter | Specification | | :--- | :--- | | **Supply Voltage (Vdd)** | 2.6V to 3.6V | | **Interface** | I2C (Inter-Integrated Circuit) | | **Field of View (FOV)** | Typically 100° to 110° (Wide Angle) | | **Object Temp Range** | -20°C to +100°C (Standard) | | **Current Consumption** | < 5μA (Standby) / ~1mA (Active) | | **Resolution** | 16-bit ADC | --- ### 2. Functional Blocks The "electronic parts" within the MAH25TCD-R package consist of several integrated stages: #### A. Thermopile Sensor Element This is the heart of the part. It consists of a series of thermocouples that generate a microvolt-level signal when exposed to infrared heat. #### B. Internal Thermistor (Reference) Since thermopiles measure a temperature *difference*, the module includes an internal NTC thermistor to measure the "Ambient Temperature" ($T_{amb}$). This allows the internal logic to calculate the absolute "Object Temperature" ($T_{obj}$). #### C. Signal Conditioning (ASIC) The raw analog signal from the thermopile is extremely weak and noisy. The internal Application Specific Integrated Circuit (ASIC) performs: * **Low Noise Amplification:** Boosting the microvolt signal. * **A/D Conversion:** A 16-bit Delta-Sigma ADC converts the analog voltage into a digital value. * **Digital Filtering:** Reduces environmental noise and interference. --- ### 3. Pin Configuration and Integration The MAH25TCD-R usually follows a standard 4-pin or SMD layout for easy integration with microcontrollers (like Arduino, ESP32, or STM32). * **VDD:** Power Supply. * **GND:** Ground. * **SDA:** I2C Serial Data line. * **SCL:** I2C Serial Clock line. --- ### 4. Common Applications * **Smart Home:** Detecting human presence to trigger lighting or HVAC. * **Security:** Motion sensing without the need for a Fresnel lens (in some configurations). * **Appliances:** Overheat protection in microwave ovens or hair dryers. * **Industrial:** Non-contact monitoring of moving parts. --- ### 5. Code Implementation (Example) To communicate with the MAH25TCD-R via I2C, a basic communication structure looks like this: ```cpp #include #define SENSOR_ADDR 0xXX // Replace with actual I2C address void setup() { Wire.begin(); Serial.begin(9600); } void loop() { Wire.beginTransmission(SENSOR_ADDR); Wire.write(0x01); // Example register for temperature data Wire.endTransmission(); Wire.requestFrom(SENSOR_ADDR, 2); if (Wire.available() <= 2) { int data = Wire.read() << 8 | Wire.read(); float temp = data * 0.02 - 273.15; // Example conversion formula Serial.println(temp); } delay(500); } ```