Microchip TechnologyUnited States

<p>The RE46C167 device is a low-power, CMOS photoelectric type, smoke detector IC. With minimal external components, this circuit will provide all the required features for a photoelectric type smoke detector. Each design incorporates a gain selectable photo amplifier for use with an infrared emitter/detector pair. An internal oscillator strobes power to the smoke detection circuitry for 100 µs every 10 seconds to keep standby current to a minimum. If smoke is sensed, the detection rate is increased to verify an alarm condition. A high gain mode is available for push button chamber testing. A check for a low battery condition and chamber integrity is performed every 43 seconds when in standby. The temporal horn pattern supports the NFPA 72 emergency evacuation signal. An interconnect pin allows multiple detectors to be connected so when one unit alarms, all units will sound. A charge dump feature will quickly discharge the interconnect line when exiting a local alarm. An internal 1.2 minute timer allows for single button, push-to-test to be used for a reduced sensitivity mode. An alarm memory feature allows the user to determine if the unit has previously entered a local alarm condition.</p>