CMOS Ionization Smoke Detector ASIC with Interconnect,
Timer Mode and Tone Select
A Subsidiary of Microchip Technology Inc.
Typical Application – 2 Button Operation – 2/3 Duty Cycle Continuous Tone Horn Pattern
Notes for Application Drawing Figure 4:
Select R5 and R6 values for the correct level to test the ion chamber. The voltage level at the TSTART input (pin 1) must be
greater than the minimum VIH level to initiate the timer mode. Pin 1 has an internal 180K nominal pull down which must be
Select R9 to reduce sensitivity during the timer mode.
R3, R4 and C1 are typical values and may be adjusted to maximize sound pressure.
C2 should be located as close as possible to the device power pins.
Route the pin 8 PC board trace away from pin 7 to avoid coupling.
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