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.

Features

Circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 Specifications

Operating Voltage Range: 6 to 12 V

Operating Temperature Range: - 10 to 60°C

Average Supply Current: 12 µA

Power-On Reset Places IC in Standby Mode (Non-Alarm State)

Electrostatic Discharge (ESD) and Latch Up Protection Circuitry on All Pins

Chip Complexity: 2000 FETs, 12 NPNs, 16 Resistors, and 10 Capacitors

Ideal for battery powered applications.