RE46C165 Datasheet, PDF (15/30 Pages) Microchip Technology – CMOS Photoelectric Smoke Detector ASIC with Interconnect, Timer Mode and Alarm Memory

RE46C165/6/7/8
TABLE 3-1:
Pin Name
I/O
VSEN
FEED
COSC
HORNB
LED
DIAGNOSTIC MODE PIN FUNCTION
Pin
Number
7
15
10
12
8
11
Function
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.
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.
If VSEN is low, then taking this input high will enable hysteresis, which is a nominal
10% gain increase in normal gain mode.
If desired, this pin can be driven by an external clock.
This pin becomes the smoke integrator output. A high level indicates that an alarm con-
dition has been detected.
The LED pin is used as a low battery indicator. For V_DD above the low battery thresh-
old, the open drain NMOS is off. If V_DD falls below the threshold, the NMOS turns on.
Oscillator
Internal Clock
STROBE
T_POSC
T_{ST ON}
IRED
LED
Standby, No Alarm (not to Scale)
T_IRON
T_PER0
T_IRON
T_PLED1
LED
STROBE
Horn
STROBE
Horn
Low Supply Test Failure
Low Batt eryWarning Chirp
Low Bat t ery Test
Low Batt eryTest
T_HOF3
T_HON2
T_HPER2
T_PER6
Chamber Fail Test Failure
Chamber Fail Test
T_HON2
T_HOF4
T_HOF5
T_HPER2
Chamber Test and Warning is Offset from Low Battery Test and Warning by 21.3 Seconds.
FIGURE 3-1:
RE46C165/6/7/8 Timing Diagram – Standby, Low Battery, Chamber Fail.
 2010 Microchip Technology Inc.
DS22251A-page 15