The **MH18FAG-R** is a specific electronic component, typically categorized as a **Unipolar Hall Effect Sensor IC**. It is widely used in automotive, industrial, and consumer electronics for non-contact switching and position sensing. --- ## 1. Technical Specifications The following table summarizes the key electrical and physical characteristics of the MH18FAG-R: | Parameter | Specification | | :--- | :--- | | **Technology** | Hall Effect (Magnetic Field Sensing) | | **Magnetic Type** | Unipolar (Responds to a single magnetic pole, usually South) | | **Operating Voltage (Vcc)** | 3.0V to 24V DC | | **Output Type** | Open-Drain / Open-Collector | | **Supply Current** | ~5mA (Max) | | **Operating Temperature** | -40°C to +125°C | | **Package Type** | SOT-23 (Surface Mount) or TO-92S | --- ## 2. Pinout Configuration The device usually features three pins, which are essential for its operation in a circuit: 1. **VDD (Supply):** Power input (3V - 24V). 2. **GND (Ground):** Common ground reference. 3. **OUT (Output):** Signal output. This pin pulls LOW when a magnetic field of sufficient strength is detected. --- ## 3. Working Principle The MH18FAG-R operates based on the Hall Effect. When a magnetic field (specifically the South pole) approaches the sensor and exceeds the **Operating Point (Bop)**, the internal transistor turns on, pulling the Output pin to Ground. ### Logic States: * **Magnetic Field Present:** Output is **LOW** (0V). * **Magnetic Field Absent:** Output is **HIGH** (Requires an external pull-up resistor). --- ## 4. Typical Application Circuit Because the output is Open-Drain, a pull-up resistor is required to interface with microcontrollers like Arduino or ESP32. ```cpp // Simple Arduino Logic for MH18FAG-R const int sensorPin = 2; // Connected to 'OUT' pin void setup() { pinMode(sensorPin, INPUT_PULLUP); // Internal pull-up if external is missing Serial.begin(9600); } void loop() { int state = digitalRead(sensorPin); if (state == LOW) { Serial.println("Magnet Detected!"); } } ``` --- ## 5. Key Features and Uses * **Protection:** Often includes reverse voltage protection and temperature compensation. * **Common Uses:** * Speedometers (counting wheel rotations). * Proximity switches (door/window sensors). * BLDC motor commutation. * Liquid level sensing (via a floating magnet).