 2010 Microchip Technology Inc.

DS22251A-page 15

RE46C165/6/7/8

FIGURE 3-1:

RE46C165/6/7/8 Timing Diagram – Standby, Low Battery, Chamber Fail.

TABLE 3-1:

DIAGNOSTIC MODE PIN FUNCTION

Pin Name

Pin

Number

Function

I/O

7

Disabled as an output. A high on this pin directs the photo amplifier output to pin C1 or

C2, determined by the level on VSEN. Amplification occurs during the IRED active time.

VSEN

15

If I/O is high, then this pin controls the gain capacitor that is used. If VSEN is low, the

normal gain is selected and the photo amplifier output appears on C1. If VSEN is high,

high gain is selected, and the photo amplifier output is on C2.

FEED

10

If VSEN is low, then taking this input high will enable hysteresis, which is a nominal

10% gain increase in normal gain mode.

COSC

12

If desired, this pin can be driven by an external clock.

HORNB

8

This pin becomes the smoke integrator output. A high level indicates that an alarm con-

dition has been detected.

LED

11

Standby, No Alarm (not to Scale)

Oscillator

T

POSC

T

IRON

Internal Clock

T

STON

T

PER0

STROBE

T

IRON

IRED

T

PLED1

LED

Low Supply Test Failure

LED

STROBE

Low Battery Test

Low BatteryTest

T

HON2

Low BatteryWarning Chirp

T

HOF3

Horn

T

HPER2

T

PER6

Chamber Fail Test Failure

STROBE

Chamber Fail Test

T

HON2

T

HOF4

T

HOF5

Horn

T

HPER2

Chamber Test and Warning is Offset from Low Battery Test and Warning by 21.3 Seconds.