5354
SMOKE DETECTOR
WITH INTERCONNECT
NO CONNECT.
I/O
LOW-V SET
NO CONNECT.
LED
+ SUPPLY
TIMING RES.
FEEDBACK
1
2
3
4
5
6
7
8
V
SS
V
DD
NC
NC
LOGIC
16
15
14
13
12
11
10
9
GUARD 2
DETECT. IN
GUARD 1
SENSITIVITY
SET
OSC. CAP.
HORN 2
HORN 1
– SUPPLY
Data Sheet
26110.6
The A5354CA is a low-current, CMOS 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 an alarm. In addition,
special features are incorporated to facilitate alignment and test of the
finished smoke detector. This device is designed to comply with
Underwriters Laboratories Specification UL217.
The internal oscillator and timing circuitry keeps standby power to
a minimum by powering down the device for 1.66 seconds and sensing
smoke for only 10 ms. Every 24 on/off cycles, a check is made for 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 A5354CA is supplied in a low-cost, 16-pin dual in-line plastic
package. It is rated for continuous operation over the temperature
range of 0°C to +50°C. Similar devices, with an internal timer to allow
for a period of reduced sensitivity (“hush”), are available as the
A5348CA.
OSC. &
TIMING
HORN
DRIVER
Dwg PC-004-1
FEATURES
ABSOLUTE MAXIMUM RATINGS
(Voltages are referenced to V
SS
)
Supply Voltage Range,
V
DD
................................
-0.5 V to +15 V
Reverse Battery (10.5 V) .......................
20 s
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
.....................................
0
°
C to +50
°
C
Storage Temperature Range,
T
S
...............................
-55
°
C to +125
°
C
CAUTION: CMOS devices have input static
protection but are susceptible to damage when
exposed to extremely high static electrical
charges.
s
s
s
s
s
s
s
Interconnect Up to 125 Detectors
Piezoelectric Horn Driver
Guard Outputs for Detector Input
Pulse Testing for Low Battery
Power-ON Reset
Internal Reverse Battery Protection
Built-In Hysteresis Reduces False Triggering
Always order by complete part number:
A5354CA
.
5354
SMOKE DETECTOR
with INTERCONNECT
FUNCTIONAL BLOCK DIAGRAM AND TYPICAL APPLICATION
+ SUPPLY V
DD
6
9V
I/O
2
V
DD
FEEDBACK
8
11
HORN
2
+
3
LOW-V
SET
–
+
LOGIC
10
HORN 1
5
LED
+V
SENSITIVITY
SET
– SUPPLY
9
V SS
14
GUARD 1
+V
DETECT. 15
IN
16
GUARD 2
1
NO
CONNECTION
4
NO
CONNECTION
–
+
–
+
13
POWER-ON
RESET
TIMING RES.
7
OSCILLATOR
& TIMING
OSC. CAP.
12
+V
Dwg. FC-001-4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1996, Allegro MicroSystems, Inc.
5354
SMOKE DETECTOR
with INTERCONNECT
ELECTRICAL CHARACTERISTICS at T
A
= +25
°
C, V
DD
= 9.0 V, V
SS
= 0 V, C
12
= 0.1
µ
F,
R
7
= 8.2 M
Ω
(unless otherwise noted).
Characteristic
Supply Voltage Range
Detector Input Current
Input Offset Voltage
Test
Pin
6
15
14-15
16-15
15-13
Hysteresis
Common Mode Range
13
14-15
13-15
Active Guard Impedance
14
16
Oscillator Period
12
Limits
Test Conditions
Operating
0 to 40% RH, V
IN
= 0 to 9.0 V
Active Guard
Active Guard
Detect Comparator
No Alarm to Alarm
Guard Amplifier
Smoke Comparator
to V
SS
to V
SS
No Alarm
Alarm
Oscillator Pulse Width
Low Voltage Threshold
Sensitivity Adjust Voltage
Horn Output Voltage
12
6
13
10-11
T
A
= 0°C to 50°C
V
13
/V
DD
, pin 13 open circuit
I
OUT
= 16 mA, V
DD
= 9.0 V
I
OUT
= 16 mA, V
DD
= 7.2 V
I
OUT
= -16 mA, V
DD
= 9.0 V
I
OUT
= -16 mA, V
DD
= 7.2 V
Horn Output ON Time
10-11
Alarm
Low Battery
Horn Output OFF Time
10-11
Alarm
Low Battery
LED Output ON Current
LED Output ON Time
LED Output OFF Time
5
5
5
No Alarm, In Standby
V
DD
= 7.2 V, V
OUT
= 1.0 V
Min.
6.0
—
—
—
—
90
2.0
0.5
—
—
1.34
32
8.0
7.2
48.5
—
—
8.5
6.3
120
8.0
60
32
10
8.0
32
Typ.
9.0
—
—
—
—
130
—
—
10
500
1.67
40
10
—
50
0.1
—
8.8
—
160
10
80
40
—
10
40
Max.
12
±1.0
±100
±100
±50
170
V
DD
- 0.5
V
DD
- 2.0
—
—
2.00
48
12
7.8
51.5
0.5
0.9
—
—
208
12
104
48
—
12
48
Units
V
pA
mV
mV
mV
mV
V
V
kΩ
kΩ
s
ms
ms
V
%
V
V
V
V
ms
ms
ms
s
mA
ms
s
Continued next page . . .
NOTE 1: Negative current is defined as coming out of (sourcing) the specified device pin.
NOTE 2: Alarm (Smoke) Condition is defined as V
15
< V
13
; No Alarm (No Smoke) Condition as V
15
> V
13
.
5354
SMOKE DETECTOR
with INTERCONNECT
ELECTRICAL CHARACTERISTICS continued
Test
Pin
2
Limits
Test Conditions
No Alarm, V
I/O
= V
DD
- 2.0 V
Alarm, V
I/O
= V
DD
- 2.0 V
I/O Alarm Voltage
I/O Delay
Supply Current
2
2
6
External “Alarm” In
“Alarm” Out
V
DD
= 9.0 V, No Alarm, No Loads
V
DD
= 12 V, No Alarm, No Loads
NOTE 1: Negative current is defined as coming out of (sourcing) the specified device pin.
NOTE 2: Alarm (Smoke) Condition is defined as V
15
< V
13
; No Alarm (No Smoke) Condition as V
15
> V
13
.
Characteristic
I/O Current
Min.
25
-7.5
3.0
—
—
—
Typ.
—
—
—
3.0
5.0
—
Max.
60
—
—
—
9.0
12
Units
µA
mA
V
s
µA
µA
CIRCUIT DESCRIPTION
The A5354CA is a low-current CMOS circuit
providing all of the required features for an
ionization-type smoke detector.
Oscillator.
An internal oscillator operates
with a period of 1.67 seconds during no-
smoke conditions. Every 1.67 seconds,
internal power is applied to the entire circuit
and a check is made for smoke. Every 24
clock cycles (40 seconds), the LED is pulsed
and a check is made for low battery by
comparing V
DD
to an internal reference.
Because very-low currents are used in the
device, the oscillator capacitor at pin 12
should be a low-leakage type (PTFE, polysty-
rene, or polypropylene).
Detector Circuitry.
When smoke is de-
tected, the resistor divider network that sets
the sensitivity (smoke trip point) is altered to
increase the sensitivity set voltage (pin 13)
by typically 130 mV with no external connec-
tions to pins 3 or 13. This provides hyster-
esis and reduces false triggering. An active
guard is provided on both pins adjacent to
the detector input (pin 15). The voltage at
pins 14 and 16 will be within 100 mV of the
input. This will keep surface leakage currents to a minimum and
provide a method of measuring the input voltage without loading the
ionization chamber. The active guard amplifier is not power strobed
and thus provides constant protection from surface leakage currents.
The detector input has internal diode protection against static damage.
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
DD
and V
SS
. The sensitivity
can be externally adjusted to the individual characteristics of the
ionization chamber by connecting a resistor between pin 13 and V
DD
, or
between pin 13 and V
SS
.
Low Battery.
The low battery threshold is set internally by a voltage
divider connected between V
DD
and V
SS
. The threshold can be in-
creased by connecting a resistor between pin 3 and V
DD
. The thresh-
old can be decreased by connecting a resistor between pin 3 and V
SS
.
The battery voltage level is 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
Ω
to 1000
Ω)
such that the
battery loading remains at 10 mA.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
5354
SMOKE DETECTOR
with INTERCONNECT
TYPICAL APPLICATION
I/O.
A connection is provided at pin 2 to
allow multiple smoke detectors 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 intercon-
nected 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
DD
and
monitoring HORN
1
(pin 10). 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 opera-
tion of the comparator circuitry.
9V
200 kΩ
200 kΩ
1
200
Ω
2
TO
OTHER
UNITS
NOTE
2
330
Ω
5
6
8.2 MΩ
7
1
µF
8
3
4
NC
LOGIC
16
15
14
PUSH
TO
TEST
NC
OSC. &
TIMING
13
12
0.1
µF
NOTE
1
V
DD
HORN
DRIVER
11
10
V
SS
9
1 MΩ
330 kΩ
0.001
µF
Dwg. EC-005-4
NOTE 1: An external resistor divider is used to adjust sensitivity for the
particular smoke chamber.
NOTE 2: A resistor to ground or V
DD
may be added to this pin to modify
low battery voltage threshold.
TIMING DIAGRAMS IN TYPICAL APPLICATION
NO ALARM
NO LOW BATTERY
STANDBY MODE
ALARM
NO LOW BATTERY
ALARM AND
LOW BATTERY
NO ALARM
LOW BATTERY
V12
OSC. CAP
1.67 s
10 ms
40 ms
INTERNAL
CLOCK
24 CLOCK CYCLES
24 CLOCK CYCLES
30 CLOCK CYCLES
LED
LED OFF
LED
ON
12 CLOCK CYCLES
6 CLOCK CYCLES
6 CLOCK CYCLES
SMOKE
COMPARATOR
SAMPLE
LOW BATTERY
WARNING
HORN
ON
OFF
HORN
SMOKE
CHAMBER
V15 < V13 (SMOKE)
V15 > V13 (NO SMOKE)
Dwg. WC-003
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