RE46C120

CMOS Ionization Smoke Detector ASIC

R&E International

Product Specification

A Subsidiary of Microchip Technology Inc.

© 2009 Microchip Technology Inc.

DS22157A-page 6

Timing Diagram

StandbyMode; NoLowBattery; NoAlarm

Alarm; NoLowBattery

Alarm; LowBattery

Oscillator

1.67S

10mS

Internal Clock

24ClockCycles(40S)

LED

DETCOMP (pin1)

Sample(2/3Duty)

Sample(NFPA72)

LowBatteryWarningChirp

Horn(2/3DutyCycle, TONE=VSS)

LowBatteryWarningChirp

Horn(NFPA72, TONE=Open)

SeeFigureBelowfor CompleteTemporal HornCycle

Notes:

1. Smokeis not sampledwhenthehornis activesothehorncycleisself completing

2. Lowbatterywarningchirpis suppressedinalarm

CompleteTemporal HornPattern

Pin15>Pin13

Pin13>Pin15; 130mVLevel Shift onPin13

NoAlarm; LowBattery

24ClockCycles(1S)

Pin15>Pin13