SmartElex LHI778 PIR Motion Sensor Module

Overview

The SmartElex LHI778 PIR Motion Sensor Module is a compact passive infrared (PIR) motion detection module designed for detecting human movement based on infrared radiation changes.

• Uses LHI778 pyroelectric sensor element

• Provides digital output (HIGH/LOW)

• Designed for low-power motion detection systems

Commonly used as a core PIR sensing module in automation and security systems

Working Principle

• Detects infrared radiation (714 m wavelength) emitted by human bodies

• Internal process:

  • IR change pyroelectric signal

  • Amplification + filtering

  • Threshold detection digital output

   

Motion causes change in IR output goes HIGH

lg>Detection Range: 0.1 m to 6 m (typical ~3 m)

Detection Angle: ~120 field of view Infrared Band: 7 14 m

Performance depends on:

• Fresnel lens

• Ambient temperature

• Motion direction

Electrical Characteristics

• Operating Voltage: 3V 5V

• Current Consumption: ~100 150 A

Low power suitable for battery-powered systems

Output Characteristics

• Type: Digital output

• Logic:

  • HIGH Motion detected

  • LOW No motion

   

Direct interface with microcontrollers

Timing Characteristics

• Delay Time: 0.3 seconds to 25 seconds (adjustable)

lroelectric sensor (LHI778 element)

Signal amplifier Band-pass filter Comparator / threshold detector Control circuit

Fully integrated motion detection system

Functional Features

• Adjustable:

  • Detection range

  • Output delay

   

• High sensitivity to human motion

• Built-in noise filtering

• Stable digital output

Performance Characteristics

• High sensitivity and reliability

• Low power consumption

• Good noise immunity

• Fast response to motion

Functional Behavior

• Detects dynamic IR changes only

• Best sensitivity when motion is:

  • Across the sensor field

   

• Output:

  • HIGH during detection + delay period

  • Returns LOW after timeout

   

Key Teotion detection

Wide detection angle (120) Adjustable delay (0.325 s) Low power consumption (A range) Digital output Compact design Works on 3V5V

Advantages

• Simple and easy to use

• Low power consumption

• Adjustable parameters

• Reliable motion detection

• Compatible with most microcontrollers

Limitations

• Cannot detect stationary objects

• Sensitive to:

  • Temperature variations

  • Heat sources

   

• Requires proper lens alignment

• Limited range compared to advanced PIR modules

Technical Summary

The LHI778 PIR module is a basic yet reliable motion detection solution that:

• Uses pyroelectric IR sensing

• Provides digital motion output

• Offers adjustable dis best suited for:

  • Simple motion detection systems

  • Low-power embedded and IoT applications