SmartElex BX404 Digital PIR Motion Sensor

Overview

The SmartElex BX404 Digital PIR Motion Sensor is a low-power intelligent passive infrared (PIR) sensor designed for accurate human motion detection.

• Integrates pyroelectric sensing + digital processing

• Provides direct digital output

• Designed for energy-efficient embedded systems

Unlike basic PIR elements, the BX404 includes on-chip signal processing, making it a complete motion detection solution.

Working Principle

• Detects infrared radiation changes from moving human bodies

• Uses a pyroelectric sensing element

• Internal circuit:

  • Amplifies signal

  • Filters noise

  • Converts analog digital output

   

Motion detected output triggered (REecture

• Pyroelectric IR sensing element

• High-impedance differential input stage

• Digital signal processing (DSP) circuit

• Built-in filtering (band-pass filter)

• Threshold detection logic

Fully digital processing improves stability and reduces drift

Electrical Characteristics

• Operating Voltage: 2.2V 3.7V

• Static Current Consumption: < 11 A

• Ultra-low power ideal for battery-powered devices

Detection Characteristics

• Detection Range: up to 12 meters

• Detection Angle: ~120 (horizontal)

• Sensing Window: ~4 4 mm

Range depends on lens (e.g., Fresnel lens)

Output Characteristics

• Output Type: Digital (HIGH / LOW)

• HIGH Motion detected

• LOW No motion

Directly usable with microcontrollers

Functional Features

• Supports connection to external PIR elements (up to 2 sensors)

• Adjustable timing via external DC voltage inputs

• Built-in:

  • Noise filtering

  • Interference suppression

  • Stable threshold detection

   

Performance Characteristics

• No drift or aging effects (digital processing)

• High noise immunity (RF interference resistant)

• Stable operation even in noisy environments

Functional Behavior

• Detects dynamic IR changes (motion only)

• Best sensitivity when motion is:

  • Across the sensor field

   

• Provides:

  • Clean digital pulse output

   

Key Technical Features

• Ultra-low power (<11 A)

• Wide detection angle (120)

• Long detection range (~12 m)

• Integrated digital processing

• Adjustable timing parameters

• High noise immunity

• Direct digital interface

Advantages

• No external signal conditioning required

• Very low power consumption

• Stable and reliable detection

• Compact and lightweight design

• Suitable for embedded and IoT systems

Limitations

• Cannot detect stationary objects

• Requires:

  • Proper lens for full range

   

• Sensitive to:

  • Temperature variations

  • External heat sources

   

• Requires correct placement for optimal detection

Technical Summary

The BX404 is an advanced digital PIR sensor IC/moduleensing + signal processing

Outputs direct digital motion detection Provides high stability with ultra-low power consumption

Compared to simpler PIR sensors:

• More stable (less noise & drift)

• Better interference rejection

• Flexible timing control</