The RE46C166 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. A continuous tone horn pattern is used for the alarm condition. 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 9 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.