Sensors

6

Freescale Semiconductor

MC14467-1

Figure 7. Timing Diagram

Smoke/no Low Battery

Smoke/Low Battery

No Smoke/low Battery

10 m s

40 m s

1.67 s

Oscillator

(Pin 12)

Detect Out

(Pin 1)

Low Battery Out

(Pin 4)

Hysteresis (Internal)

(Pins 13 & 14)

Sample (Internal)

Smoke

(Pins 10 & 11)

Horn

(Note 1)

LED

(Pin 5)

(Note 3)

Battery Test

(Note 3)

Suppressed Chirp

24 Clock Cycles

(40 s)

24 Clock Cycles (0.96 s)

24 Clock Cycles

6 Clock

Cycles (10.0 s)

Notes:

1. Horn modulation is self-completing. When going from smoke to no smoke, the alarm condition will terminate only when horn is off.

2. Comparators are strobed on once per clock cycle (1.67 s for no smoke, 40 ms for smoke).

3. Low battery comparator information is latched only during LED pulse.

4. ~ 100 mVp–p swing.

Standby

No Smoke/

No Low Battery