RE46C122

CMOS Ionization Smoke Detector ASIC with

R&E International

Interconnect and Timer Mode

A Subsidiary of Microchip Technology Inc.

Product Specification

© 2009 Microchip Technology Inc.

DS22173A-page 7

Typical Single Button Application

Figure 3

Notes:

Select R5 and R6 for the correct level to test the ion chamber. The voltage level on pin 1 (TSTART) must be

greater than the VIH level to initiate the timer. Pin 1 has an internal 180K nominal pull down which must be

considered.

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.