MC145010

Freescale Semiconductor Technical Data Photoelectric Smoke Detector IC with I/O The CMOS MC145010 is an advanced smoke detector component containing sophisticated very-low-power analog and digital circuitry. The IC is used with an infrared photoelectric chamber. Detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. When detection occurs, a pulsating alarm is sounded via on-chip push-pull drivers and an external piezoelectric transducer. The variable-gain photo amplifier allows direct interface to IR detectors (photodiodes). Two external capacitors, C1 and C2, C1 being the larger, determine the gain settings. Low gain is selected by the IC during most of the standby state. Medium gain is selected during a local-smoke condition. High gain is used during push button test. During standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain, also. The I/O pin, in combination with VSS, can be use...