AM312 Mini PIR Motion Sensor – 2.7-12V, 3-5m Detection Range

The AM312 Mini PIR Motion Sensor is an ultra-compact passive infrared (PIR) sensor designed to detect human movement and changes in infrared radiation within its sensing area.

With its miniature size, very low power consumption, digital output, and wide 2.7–12V DC operating range, the AM312 is ideal for smart-home devices, security systems, automatic lighting, battery-powered IoT projects, robotics, and embedded motion-detection applications.

Unlike active infrared sensors, the AM312 does not transmit infrared light. It passively detects changes in infrared energy caused by people or other warm objects moving across its field of view.

Technical Specifications

• Model: AM312
• Sensor Type: Passive Infrared (PIR) Motion Sensor
• Operating Voltage: 2.7–12V DC
• Static Power Consumption: <0.1mA
• Detection Distance: Approx. 3–5m
• Detection Angle: Up to approximately 100° cone
• Trigger Mode: Repeatable
• Output Type: Digital HIGH/LOW
• Delay Time: Approx. 2s
• Blocking Time: Approx. 2s
• Operating Temperature: -20°C to +60°C
• PCB Dimensions: Approx. 10 × 8mm
• Lens Type: Mini Fresnel Lens
• Interface: 3-Pin – VCC / OUT / GND
• Sensitivity Adjustment: Fixed / Non-Adjustable
• Delay Adjustment: Fixed / Non-Adjustable

PIR Human Motion Detection

The AM312 uses pyroelectric infrared sensing technology to detect changes in infrared radiation within its field of view.

When a person moves through the detection area, the resulting change in infrared energy is processed by the sensor's internal circuitry and converted into a digital output signal.

This makes the module easy to interface with microcontrollers without requiring an external analog-to-digital converter.

Repeatable Trigger Operation

The AM312 operates in repeatable trigger mode.

When movement is detected, the output changes to its active HIGH state. If additional movement continues to be detected during the delay period, the sensor automatically extends the active period.

Once movement stops and the delay period expires, the output returns LOW.

This behavior is particularly useful for applications such as automatic lighting, where the controlled device should remain active while movement continues.

Ultra-Low Power Consumption

With static power consumption below approximately 0.1mA, the AM312 is well suited to low-power and battery-operated applications.

Its compact dimensions also make it a useful alternative to larger PIR modules when installation space is limited.

Simple 3-Pin Connection

The AM312 uses a simple three-pin interface:

VCC – 2.7-12V DC Power Input
OUT – Digital Motion Detection Output
GND – Ground

The digital output can be connected to a suitable microcontroller GPIO input for motion detection.

Always verify the pin markings on the actual module before connecting power, as orientation can vary between suppliers.

Microcontroller Compatibility

The AM312 can be integrated with common development platforms including:

Arduino
ESP32
ESP8266
Raspberry Pi Pico
STM32
Raspberry Pi GPIO

Because it provides a simple digital output, no complex communication protocol or dedicated sensor library is normally required.

The microcontroller simply monitors the output pin to determine whether movement has been detected.

Applications

Ideal for motion-activated lighting, smart-home automation, security alarms, occupancy detection, battery-powered IoT devices, automatic doors, robotics, smart appliances, ESP32 projects, Arduino projects, wireless sensor nodes, automatic switching systems, and embedded motion detectors.

Important Note

The AM312 is a motion detector, not a distance sensor. The specified 3–5m range represents the approximate area in which movement may be detected and does not provide a measurement of how far away a person is.

Detection performance can be affected by ambient temperature, direction of movement, installation height, lens orientation, nearby heat sources, airflow, and environmental conditions.

The AM312 generally provides fixed sensitivity and timing behavior, unlike larger PIR modules such as the HC-SR501 that commonly include adjustable potentiometers.

For best performance, avoid installing the sensor directly beside heaters, air-conditioning outlets, strong sunlight, or other rapidly changing heat sources.

Package Includes

1 × AM312 Mini PIR Pyroelectric Infrared Motion Sensor Module