5358
PHOTOELECTRIC SMOKE DETECTOR
WITH INTERCONNECT AND TIMER
The A5358CA is a low-current BiCMOS circuit providing all of the
required features for a photoelectric type smoke detector. This device
can be used in conjunction with an infrared photoelectric chamber to
sense scattered light from smoke particles. Special features are
incorporated in the design to facilitate calibration and testing of the
finished detector. The device is designed to comply with Underwriters
Laboratories Specification UL217 and British Standard BS 5446,
Part 1.
A variable-gain photo amplifier can be directly interfaced to an
infrared emitter/detector pair. The amplifier gain levels are determined
by two external capacitors that are then internally selected depending
on the operating mode. Low gain is selected during standby and timer
modes. During a local alarm this low gain is increased (internally) by
~10% to reduce false triggering. High gain is used during the push-
button test and during standby to periodically monitor the chamber
sensitivity.
The internal oscillator and timing circuitry keeps standby power to
a minimum by sensing for smoke every 10 seconds in a 10
µs
window.
A special three-stage speedup sensing scheme is incorporated to
minimize the time to an audible alarm and also to reduce false trigger-
ing. Also, two consecutive cycles of degraded chamber sensitivity are
required for a warning signal to occur.
The A5358CA is supplied in a low-cost 16-pin dual in-line plastic
package. It is rated for continuous operation over the temperature
range of -25°C to +75°C.
Data Sheet
26110.10A
C1
C2
DETECT
STROBE
+ SUPPLY
IRED
I/O
HORN 1
1
2
3
4
5
6
7
8
HORN
DRIVER
V
DD
LOGIC
OSC. &
TIMING
V
SS
16
15
14
13
12
11
10
9
TEST
HUSH
– SUPPLY
TIMING RES.
OSC. CAP.
LED
FEEDBACK
HORN 2
Dwg. PC-007
ABSOLUTE MAXIMUM RATINGS
(Voltages are referenced to V
SS
)
Supply Voltage Range,
V
DD
....................................
-0.5 V to +15 V
Input Voltage Range,
V
IN
............................
-0.3 V to V
DD
+ 0.3 V
Input Current, I
IN
...................................
10 mA
Operating Temperature Range,
T
A
.....................................
-25
°
C to +75
°
C
Storage Temperature Range,
T
S
...................................
-55
°
C to +125
°
C
CAUTION: CMOS devices have input static
protection but are susceptible to damage if exposed
to extremely high static electrical charges.
FEATURES
s
s
s
s
s
s
s
s
Interconnect Up to 50 Detectors
Piezoelectric Horn Driver
All Internal Low-Battery Detection
Power-ON Reset
Internal Timer & Control for Reduced Sensitivity
Built-In Circuits to Reduce False Triggering
6 V to 12 V Operating Voltage Range
ESD-Protection Circuitry on All Pins
Always order by complete part number:
A5358CA
.
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
