A5347CA Allegro Microsystems Inc, A5347CA Datasheet - Page 5

• Manufacturer Part Number: A5347CA
• Manufacturer: Allegro Microsystems Inc

Specifications of A5347CA

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 50C
• Package Type: PDIP
• Rad Hardened: No
• Lead Free Status / Rohs Status: Not Compliant

Alarm Circuitry. If smoke is detected, the
oscillator period changes to 40 ms and the
horn is enabled. The horn output is typically
160 ms ON, 80 ms OFF. During the OFF
time, smoke is again checked and will inhibit
further alarm output if smoke is not sensed.
During smoke conditions the low battery
alarm is inhibited and the LED is driven at a
1 Hz rate.
Sensitivity Adjust. The detector sensitivity
to smoke is set internally by a voltage divider
connected between V
sensitivity can be externally adjusted to the
individual characteristics of the ionization
chamber by connecting a resistor between
pin 13 and V
Low Battery. The low battery threshold is
set internally by a voltage divider connected
between V
increased by connecting a resistor between
pin 3 and V
creased by connecting a resistor between
pin 3 and V
checked every 40 seconds during the 10 mA,
10 ms LED pulse. If an LED is not used, it
should be replaced with an equivalent
resistor (typically 500
the battery loading remains at 10 mA.
Timer. An internal timer is provided that can
be used in various configurations to allow for
a period of reduced smoke detector sensitiv-
ity (“hush”). When a high-to-low transition
occurs at pin 1, the internal timer is reset,
the timer mode enabled, and the circuit reset
to a no alarm condition. The LED will flash
at a 10 second rate. If the level of smoke is
increased such that the reduced sensitivity
level is reached, the device will go into the
alarm condition. The timer, however, will
continue to completion of the nominal 10-1/4
minute period (368 clock cycles). If the timer
mode is not used, pin 1 should be tied low.
5347
SMOKE DETECTOR
with INTERCONNECT
and TIMER
DD
DD
SS
DD
and V
. The battery voltage level is
. The threshold can be de-
, or between pin 13 and V
SS
. The threshold can be
DD
to 1000
and V
SS
. The
) such that
SS
.
I/O. A connection is provided at pin 2 to allow multiple smoke detec-
tors to be commoned. If any single unit detects smoke (I/O is driven
high), all connected units will sound their associated horns after a
nominal 3 second delay. The LED is suppressed when an alarm is
signaled from an interconnected unit.
Testing. On power up, all internal counters are reset. Internal test
circuitry allows for low battery check by holding pins 8 and 12 low
during power up, then reducing V
All functional tests can be accelerated by driving pin 12 with a 2 kHz
square wave. The 10 ms strobe period must be maintained for proper
operation of the comparator circuitry.
NOTE 1: Use an external resistor to adjust sensitivity for a particular smoke
NOTE 2: Select resistor to reduce sensitivity during timer mode.
NOTE 3: A resistor to ground or V
NOTE 4: Reverse battery protection must be supplied externally.
NOTE 4
OTHER
UNITS
TO
9 V
chamber.
voltage threshold.
NOTE
TIMER
MODE
1 F
200
3
8.2 M
330
TYPICAL APPLICATION
1
2
3
4
5
6
7
8
V
DD
NOTE 2
DD
DRIVER
LOGIC
OSC. &
TIMING
HORN
may be added to this pin to modify low battery
DD
200 k
and monitoring HORN
V
SS
16
15
14
13
12
11
10
9
0.1 F
1
(pin 10).
NOTE
Dwg. EC-005-2
PUSH
TEST
TO
1
0.001 F