MC146012

The MC146012 is an advanced smoke detector component containing sophisticated very-low power analog and digital circuitry. The IC, when used with an infrared photoelectric chamber and a small number of external components, will detect smoke by sensing scattered light from smoke particles. When etection occurs, a pulsating alarm is sounded via on-chip push-pull drivers and an external piezoelectric transducer.

The MC146012 provides both audible and visual alarms. Upon sensing a normal smoke level, both alarms will be activated. It is possible to mute the audible alarm for approximately eight minutes through the Integrated Mute Function (IMF), although the LED will continue to flash at a high rate. This feature is resetable through a pushbutton test. The IMF feature will be overridden by remote smoke, high smoke level, timeout or reset.

The Alarm memory feature will allow for identification of an alarming detector. Through a pushbutton test, the LED will flash rapidly if there was a previous
alarm condition detected at the unit.

The variable-gain photo amplifier allows direct interface to IR detector (photodiode). The gain settings are determined by external capacitors and compensation resistors. A two stage speed-up is incorporated into the smoke monitor to minimize time and help reduce false triggering. Further reduction of
false triggering is also addressed with the double sample chamber sensitivity and double I/O sample.