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LOGIC
OSC. &
TIMING
HORN
DRIVER
GUARD
DETECT. IN
GUARD
SENSITIVITY
SET
OSC. CAP.
HORN
HORN
SUPPLY
NO CONNECT.
I / O
LOW-V SET
NO CONNECT.
LED
+ SUPPLY
TIMING RES.
FEEDBACK
1
V
DD
Dwg PC-004-1
2
2
1
V
SS
NC
NC
SMOKE DETECTOR
WITH INTERCONNECT
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.
5354
Always order by complete part number: A5354CA .
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.
Data Sheet
26110.6
FEATURES
s
Interconnect Up to 125 Detectors
s
Piezoelectric Horn Driver
s
Guard Outputs for Detector Input
s
Pulse Testing for Low Battery
s
Power-ON Reset
s
Internal Reverse Battery Protection
s
Built-In Hysteresis Reduces False Triggering
5354
SMOKE DETECTOR
with INTERCONNECT
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
FUNCTIONAL BLOCK DIAGRAM AND TYPICAL APPLICATION
9 V
LOW-V
SET
SUPPLY
+ SUPPLY
I / O
TIMING RES.
FEEDBACK
DETECT.
IN
1
2
OSC. CAP.
NO
CONNECTION
4
POWER-ON
RESET
OSCILLATOR
& TIMING
LOGIC
SENSITIVITY
SET
+
+
+
GUARD
GUARD
HORN 1
HORN
2
LED
NO
CONNECTION
+V
+V
V
DD
1
2
3
5
8
11
10
7
12
6
13
9
14
15
16
V
DD
V
SS
Dwg. FC-001-4
+
+V
Copyright 1996, Allegro MicroSystems, Inc.
ELECTRICAL CHARACTERISTICS at T
A
= +25
C, V
DD
= 9.0 V, V
SS
= 0 V, C
12
= 0.1
F,
R
7
= 8.2 M
(unless otherwise noted).
Test
Limits
Characteristic
Pin
Test Conditions
Min.
Typ.
Max.
Units
Supply Voltage Range
6
Operating
6.0
9.0
12
V
Detector Input Current
15
0 to 40% RH, V
IN
= 0 to 9.0 V
--
--
1.0
pA
Input Offset Voltage
14-15
Active Guard
--
--
100
mV
16-15
Active Guard
--
--
100
mV
15-13
Detect Comparator
--
--
50
mV
Hysteresis
13
No Alarm to Alarm
90
130
170
mV
Common Mode Range
14-15
Guard Amplifier
2.0
--
V
DD
- 0.5
V
13-15
Smoke Comparator
0.5
--
V
DD
- 2.0
V
Active Guard Impedance
14
to V
SS
--
10
--
k
16
to V
SS
--
500
--
k
Oscillator Period
12
No Alarm
1.34
1.67
2.00
s
Alarm
32
40
48
ms
Oscillator Pulse Width
12
8.0
10
12
ms
Low Voltage Threshold
6
T
A
= 0
C to 50
C
7.2
--
7.8
V
Sensitivity Adjust Voltage
13
V
13
/V
DD
, pin 13 open circuit
48.5
50
51.5
%
Horn Output Voltage
10-11
I
OUT
= 16 mA, V
DD
= 9.0 V
--
0.1
0.5
V
I
OUT
= 16 mA, V
DD
= 7.2 V
--
--
0.9
V
I
OUT
= -16 mA, V
DD
= 9.0 V
8.5
8.8
--
V
I
OUT
= -16 mA, V
DD
= 7.2 V
6.3
--
--
V
Horn Output ON Time
10-11
Alarm
120
160
208
ms
Low Battery
8.0
10
12
ms
Horn Output OFF Time
10-11
Alarm
60
80
104
ms
Low Battery
32
40
48
s
LED Output ON Current
5
V
DD
= 7.2 V, V
OUT
= 1.0 V
10
--
--
mA
LED Output ON Time
5
8.0
10
12
ms
LED Output OFF Time
5
No Alarm, In Standby
32
40
48
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
5354
SMOKE DETECTOR
with INTERCONNECT
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
I/O Current
2
No Alarm, V
I/O
= V
DD
- 2.0 V
25
--
60
A
Alarm, V
I/O
= V
DD
- 2.0 V
-7.5
--
--
mA
I/O Alarm Voltage
2
External "Alarm" In
3.0
--
--
V
I/O Delay
2
"Alarm" Out
--
3.0
--
s
Supply Current
6
V
DD
= 9.0 V, No Alarm, No Loads
--
5.0
9.0
A
V
DD
= 12 V, No Alarm, No Loads
--
--
12
A
ELECTRICAL CHARACTERISTICS continued
Limits
Characteristic
Pin
Test Conditions
Min.
Typ.
Max.
Units
Test
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
.
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
to 1000
) such that the
battery loading remains at 10 mA.
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
TIMING DIAGRAMS IN TYPICAL APPLICATION
TYPICAL APPLICATION
NO ALARM
NO LOW BATTERY
STANDBY MODE
1.67 s
10 ms
40 ms
24 CLOCK CYCLES
V15 > V13 (NO SMOKE)
V15 < V13 (SMOKE)
V12
OSC. CAP
INTERNAL
CLOCK
LED
SMOKE
COMPARATOR
SMOKE
CHAMBER
HORN
SAMPLE
ALARM
NO LOW BATTERY
30 CLOCK CYCLES
LOW BATTERY
WARNING
HORN
ON
OFF
ALARM AND
LOW BATTERY
NO ALARM
LOW BATTERY
Dwg. WC-003
24 CLOCK CYCLES
LED OFF
LED
ON
12 CLOCK CYCLES
6 CLOCK CYCLES
6 CLOCK CYCLES
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.
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.
TO
OTHER
UNITS
NOTE
1
NOTE
2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
LOGIC
OSC. &
TIMING
HORN
DRIVER
V
DD
Dwg. EC-005-4
V
SS
9 V
PUSH
TO
TEST
200 k
200 k
200
8.2 M
1
F
0.1
F
1 M
330 k
0.001
F
330
NC
NC
5354
SMOKE DETECTOR
with INTERCONNECT
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