RE46C145
CMOS Photoelectric Smoke Detector ASIC with Interconnect and Timer Mode
R&E International
Product Specification
PIN DESCRIPTIONS
PIN#
PIN NAME
DESCRIPTION
1
C1
The capacitor connected to this pin sets the photo amplifier gain (high) for the
push-to-test and chamber sensitivity test. The size of this capacitor will depend
on the chamber background reflections. A=1+(C1/10) where C1 is in pF. The
gain should be <10000.
2
C2
The capacitor connected to this pin sets the photo amplifier gain (normal) during
standby. The value of this capacitor will depend on the smoke sensitivity
required. A=1+(C2/10) where C2 is in pF.
3
4
DETECT
STROBE
Positive input to the photo amplifier. This input is normally connected to the
cathode of an external photo diode operated at zero bias.
Regulated output voltage of VDD-5 which is active during a test for smoke. This
output is the negative side of the photo amplifier circuitry.
5
6
VDD
Connect to the positive supply voltage
IRED
Provides a regulated pulsed output voltage pre-driver for the infrared emitter.
This output usually drives the base of an NPN transistor.
7
IO
This bidirectional pin provides the capability to interconnect many detectors in a
single system. This pin has an internal pull-down device.
8
9
HB
HS
This pin is connected to the metal electrode of a piezoelectric transducer.
HS is a complementary output to HB and connects to the ceramic electrode of
the piezoelectric transducer.
10
FEED
Usually connected to the feedback electrode through a current limiting resistor. If
not used this pin must be connected to VDD or VSS.
11
12
LED
Open drain NMOS output used to drive a visible LED.
COSC
A capacitor connected to this pin with a parallel resistor sets the internal clock
low time which is approximately the clock period.
13
ROSC
A resistor between this pin and pin 12 (COSC) sets the internal clock high time.
This also sets the IRED pulse width (100-200uS).
14
15
VSS
Connect to the negative supply voltage.
VSEN
In the timer mode this input pin can be used to set an external smoke
comparator reference.
16
TEST
This input is used to invoke two test modes and the timer mode. This input has
an internal pull-down.
Telephone 610.992.0727
Page 6 of 12
Facsimile 610.992.0734
E-mail: rande@randeint.com
DS-RE46C145-121806
This datasheet contains PROPRIETARY and CONFIDENTIAL information.
RANDE [ R & E INTERNATIONAL, INC. ]
