Document Number: MC146012
Rev 0, 09/2005
Low Power CMOS Photoelectric
Smoke Detector IC
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
detection 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.
LOW POWER CMOS
• Integrated Mute Function (IMF) to Temporarily Disable Horn
• Alarm Memory to Help Identify Alarming Unit
www.DataSheet4U.com• Speed-Up Sampling Rate After First Detection of Smoke
• Double Sample for Degraded Chamber Sensitivity Monitor
• Digital Noise Filter on the I/O Pin
• Power-Up and Power-Down RESET
• Low-Battery Trip Point Set Externally
• Temporal Horn Pattern
• Operating Temperature: -10 to 75°C
• Operating Voltage Range: 6.0 to 12 V
• Average Supply Current: 6.5 µA
-10 to 75°C
-10 to 75°C
© Freescale Semiconductor, Inc., 2005. All rights reserved.