A5348 Datasheet, PDF (1/9 Pages) Allegro MicroSystems – The A5348 is a low-current, BiCMOS circuit providing all of the required features for an ionization-type smoke detector.

A5348
Ionization Smoke Detector
with Interconnect and Timer
Features and Benefits
▪ Low average standby current for long battery life
▪ Interconnect up to 125 detectors
▪ Piezoelectric horn driver
▪ Guard outputs for detector input
▪ Pulse testing for low battery
▪ Power-on reset (POR)
▪ Internal reverse battery protection
▪ Timer (Hush) mode for enabling reduced sensitivity period
▪ Built-in hysteresis reduces false triggering
Package: 16-pin DIP (suffix A):
Description
The A5348 is a low-current, BiCMOS circuit providing
all of the required features for an ionization-type smoke
detector. A networking capability allows as many as 125
units to be interconnected so that if any unit senses smoke all
units will sound their alarm. In addition, special features are
incorporated to facilitate alignment and test of the finished
smoke detector.
The internal oscillator and timing circuitry keep standby power
to a minimum by powering down the device for 1.66 seconds
and sensing for smoke for only 10 ms. Every 24 on-off cycles,
a check is made for a low battery condition. By substituting
other types of sensors or a switch for the ionization detector,
this very-low–power device can be used in numerous other
battery-operated safety/security applications.
The A5348 is supplied in a low-cost 16-pin dual in-line plastic
package (DIP). It is rated for continuous operation over the
temperature range of –10°C to 60°C. The Pb (lead) free version
(suffix –T) has 100% matte tin leadframe plating.
Not to scale
Typical Application
50 kΩ
To / from
other units
9V
Timer
Mode
200 kΩ
1
TIMER START
16
GUARD2
200 Ω ₂
I/O
15
DETECT IN
A5348
C
3
LOW-V SET
14
GUARD1
4
TIMER OUT
13
SENSITIVITY SET
330 Ω ₅
12
LED
OSC CAP
8.2 MΩ
6
VDD
7 _{TIMING RES}
11
HORN2
10
HORN1
1 μF
8
FEEDBACK
9
VSS
B
200 k Ω
Push
to Test
A
0.1 μF
A Use an external resistor to adjust
sensitivity for a particular smoke chamber.
B Select resistor to reduce sensitivity
during Timer mode.
C A resistor to VSS or VDD may
be added to this pin to modify
low battery voltage threshold.
D Value of component will vary, based on
the piezoelectric horn used.
1.5 MΩ
D
220 kΩ
D
0.001 μF
D
26110.3 Rev. 4