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Effective, photoelectric smoke detection

Although studies by Texas A&M and the National Fire Protection Agency (NFPA) claim that photoelectric alarms react slower to rapidly growing fires than ionization alarms, laboratory and field tests have shown that photoelectric smoke alarms provide adequate warning for all types of fires, and are far less likely to be deactivated by occupants.

The functional principle of this smoke detector is having an IR photo diode and photo transistor arranged inside a chamber, where air, which may contain smoke from a nearby fire, flows. The light is not directed at the sensor because both the transmitter and receiver are positioned at an angle. If the air in the chamber contains particles (smoke or dust), the light is scattered, and some of it reaches the sensor, triggering the alarm.

System Benefits:

  • Utilizes the new family of RA Arm®-based microcontrollers
  • Microcontroller contains the required amplifiers needed to level the input signals
  • Very few external components needed
Smoke detector mounted on ceiling surrounded by smoke

Recommended products

Products Description Documents
Microcontroller    
RA2A1 48MHz Arm® Cortex®-M23 core with integration of a 24-bit sigma-delta ADC Datasheet
LDO    
ISL9001A LDO with low ISUPPLY, high PSSR Datasheet

 

System block diagram

block diagram
 

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