A5338CA [ALLEGRO]
Smoke Detector with Interconnect and Timer; 烟雾探测器与互连和定时器
| 型号： | A5338CA |
| 厂家： | 
ALLEGRO MICROSYSTEMS |
| 描述： | Smoke Detector with Interconnect and Timer |
| 文件： | 总8页 (文件大小：249K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A5338
Smoke Detector
with Interconnect and Timer
Package A, 16-lead DIP
The A5338CA 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 facili-
tate 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.
Approximate Scale 1:1
Features
ꢀ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
ꢀInternal timer and control for reduced sensitivity
ꢀBuilt-in hysteresis reduces false triggering
The A5338CA 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.
Typical Application
200 kΩ
9 V
50 kΩ
200 kΩ
Push to set
Push to test
16
1
GUARD2
DETECT IN
GUARD1
Smoke
Chamber
TIMER START
200
Ω
To other units
2
3
4
15
14
13
12
11
10
9
I/O
A5338
LOW-V SET
TIMER OUT
+SUPPLY or
–SUPPLY
RLV
RS
SENSIVITIVTY SET
OSC CAP
+SUPPLY or
–SUPPLY
5
6
COSC
0.1 μF
LED
330
Ω
HORN2
+SUPPLY
TIMING RES
RT
8.2 M
Ω
7
8
HORN1
Horn
1 μF
–SUPPLY
FEEDBACK
1 MΩ
200 kΩ
0.001 μF
RST
Dwg. EC-005A
26110.1
Smoke Detector with Interconnect and Timer
A5338
Functional Block Diagram
I/O
VDD
+SUPPLY
VDD
FEEDBACK
HORN2
HORN1
–
LOW-V SET
+
LED
Logic
SENSITIVITY SET
+
Power-On
Reset
–
TIMING RES
OSC CAP
Oscillator
and Timing
+
–
TIMER OUT
–SUPPLY
VSS
GUARD1
DETECT IN
GUARD2
TIMER START
Selection Guide
Part Number
A5338CA
Package
Packing
16-pin DIP, 300 mil spacing
25 pieces per tube
Absolute Maximum Ratings1
Parameter
Supply Voltage Range2
Symbol
Conditions
Min. Typ. Max. Units
VDD
–0.5
–
–
–
15
20
V
s
Reverse Battery
–
10.5 V
VDD
+ 0.3
Logic Input Voltage Range2
VI
–0.3
V
Logic Input Current
II
–
0
–
–
–
–
10
50
mA
°C
°C
°C
Operating Temperature Range (C)
Junction Temperature
TA
TJ
TS
–
150
125
Storage Temperature Range
–55
1CMOS devices have input static protection, but are susceptible to damage when exposed to extremely high static electrical charges.
.
2Voltages are references to VSS
2
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
Smoke Detector with Interconnect and Timer
A5338
Pin-out Diagram
TIMER START
I/O
1
2
3
4
16
15
14
13
12
11
10
9
GUARD2
DETECT IN
GUARD1
LOGIC
LOW-V SET
TIMER OUT
LED
SENSITIVITY SET
OSC CAP
OSC. &
TIMING
5
6
+SUPPLY
V
HORN2
DD
HORN
DRIVER
7
8
TIMING RES
FEEDBACK
HORN1
V
–SUPPLY
SS
Dwg. PC-004
Terminal List Table
Number
Name
Function
1
TIMER START
Logic input for setting device mode.
2
3
I/O
Logic input/output, where multiple detectors can be connected.
Terminal for a resistor, RLV, to the –SUPPLY pin (VSS) or to the +SUPPLY pin (VDD),
LOW-V SET
which may be added to modify the battery Low Voltage Threshold, VDDL
Terminal for a resistor, RST, to reduce sensitivity during Timer mode.
LED output.
.
4
5
TIMER OUT
LED
6
+SUPPLY
TIMING RES
FEEDBACK
–SUPPLY
HORN1
Device supply, VDD.
7
Terminal for timing resistor.
8
Feedback from horn external circuit.
9
Device supply, VSS.
10
11
12
13
14
15
16
Horn driver output 1.
HORN2
Horn driver output 2.
OSC CAP
SENSITIVITY SET
GUARD1
Terminal for timing oscillator capacitor.
Terminal for resistor, RS, to adjust sensitvity for a particular smoke chamber.
Terminal for smoke detector guard 1.
DETECT IN
GUARD2
Terminal for smoke detector input.
Terminal for smoke detector guard 2.
3
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
Smoke Detector with Interconnect and Timer
A5338
ELECTRICAL CHARACTERISTICS1 at TA = 25°C, VDD = 9.0 V, VSS = 0 V, COSC = 0.1 μF, RT = 8.2 MΩ, unless otherwise noted
Characteristic
Symbol Test Pin
Test Conditions
Min. Typ. Max. Units
Supply Voltage Range
VDD
IDD
IS
6
Operating
VDD = 9.0 V, no alarm, no loads
DD = 12 V, no alarm, no loads
0 to 40% RH, VI(detect in) = 0 to 9.0 V
6.0
—
—
–1.0
–100
–100
–50
90
9.0
5.0
—
—
—
—
—
130
12
9.0
12
1.0
100
100
50
V
μA
μA
pA
mV
mV
mV
mV
Supply Current
6
V
Detector Input Current2
15
14-15 Active guard
16-15 Active guard
15-13 Smoke detect comparator
13
Input Offset Voltage
Hysteresis
VIO
VOhys
No alarm condition to alarm
170
VDD
- 0.5
VDD
- 2.0
—
—
VIC(guard)
14-15 Guard amplifier
2.0
0.5
—
—
V
V
Common Mode Range
VIC(det)
Zguard
tOSC
13-15 Smoke detect comparator
14
16
With reference to VSS
With reference to VSS
No alarm
—
—
10
500
Ω
Ω
s
ms
ms
min
V
%
V
V
V
V
ms
ms
ms
s
V
V
Active Guard Impedance
Oscillator Period
1.34 1.67 2.00
12
Alarm
32
8.0
5.0
7.2
48.5
—
40
10
6.5
—
50
0.1
—
48
12
Oscillator Pulse Width
Timer Period
Low Voltage Threshold
Sensitivity Adjust Voltage
tw(osc)
ttimer
VDD(th)
VS
4
4
After VTIMER_START transition high-to-low (smoke detected)
8.0
7.8
51.5
0.5
0.9
—
—
208
12
104
48
—
2.5
80
—
—
12
48
12
60
—
—
6
TA = 0 to 50°C
13
VSENSITIVITY_SET/VDD, SENSITIVITY SET pin open circuit
IO(horn) = 16 mA, VDD = 9.0 V
IO(horn) = 16 mA, VDD = 7.2 V
IO(horn) = –16 mA, VDD = 9.0 V
IO(horn) = –16 mA, VDD = 7.2 V
Alarm
Low battery
Alarm
Low Battery
—
HORNx Output Voltage
VO(horn)
10-11
8.5
6.3
120
8.0
60
32
4.5
—
20
500
10
8.0
32
8.0
25
8.8
—
160
10
80
40
—
—
—
—
—
10
40
10
—
—
—
HORNx Output ON Time
HORNx Output OFF Time
TIMER START Logic Levels
ton(horn)
toff(horn)
10-11
10-11
VIH(ts)
VIL(ts)
II(ts)
IO(to)
ILED
1
1
1
4
5
5
TIMER START Input Current
TIMER OUT Output Current
LED Output ON Current
LED Output ON Time
VI(ts) = 9.0 V
VO(to) = 0.5 V
VDD = 7.2 V, VLED = 1.0 V
μA
μA
mA
ms
s
ton(led)
No alarm; in Standby mode
No alarm; in Timer mode after VTIMER_START transition high-to-low
No alarm, V(IO) = VDD - 2.0 V
Alarm, V(IO) = VDD - 2.0 V
LED Output OFF Time
toff(led)
5
2
s
μA
mA
mA
s
V
s
I/O Current2
I(io)
-7.5
5.0
Charge dump, V(io) = 1.0 V
After local alarm
External alarm signal in
I/O Charge Dump Duration
I/O Alarm Voltage
I/O Delay
tf(io)
VI(io)
td(io)
2
2
2
1.33 1.66 1.99
3.0
—
—
3.0
—
—
Alarm signal out
1Alarm (smoke detected) condition is defined as VDETECT_IN < VSENSITIVITY_SET; No-Alarm (no smoke detected) condition is defined as
VDETECT_IN > VSENSITIVITY_SET
2Negative current is defined as coming out of (sourcing) the specified device pin.
.
4
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
Smoke Detector with Interconnect and Timer
A5338
Functional Description
The A5338 is a low-current CMOS circuit providing all of the
required features for an ionization-type smoke detector.
Low Battery. The low-battery threshold is set internally by a
voltage divider connected between VDD and VSS. The threshold
can be increased by connecting a resistor, RLV, between the
LOW-V SETpin and +SUPPLY. The threshold can be decreased
by connecting RLV between LOW-V SETpin and –SUPPLY. The
battery voltage level is checked every 40 s 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 Ω), such that the bat-
tery loading remains at 10 mA.
Oscillator. An internal oscillator operates with a period of 1.67 s
during no-smoke conditions. Every 1.67 s, internal power is
applied to the entire circuit and a check is made for smoke. Every
24 oscillator cycles (40 s total), the LED is pulsed and a check is
made for low battery by comparing VDD to an internal reference.
Because very low currents are used in the device, the oscillator
capacitor, COSC, at the OSC CAP pin should be a low-leakage
type (PTFE, polystyrene, or polypropylene).
Timer. An internal timer is provided that can be used in various
configurations to allow for a period of reduced smoke detector
sensitivity, Hush mode. When a high-to-low transition occurs at
the TIMER START pin, the internal timer is reset, Timer mode is
enabled, and the circuit is reset to a no-alarm condition. Dur-
ing Hush mode, the LED will flash at a 10 s 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 6.5 minute
period (232 oscillator cycles). If Timer mode is not used, the
TIMER START pin should be tied low. While in Hush mode, the
battery is checked. If a low-battery condition is detected, the low-
battery warning chirp will be activated.
Detector Circuitry. When smoke is detected, the resistor
divider network that sets the sensitivity (smoke trip point) is
altered to increase the voltage on the SENSITIVITY SET pin by
130 mV typical, when there are no external connections to the
SENSITIVITY SET pin or LOW-V SET pin. This provides hys-
teresis and reduces false triggering. An active guard is provided
on both GUARDx pins, adjacent to the DETECT IN detec-
tor input pin. The voltage at the GUARDx pins will be within
100 mV of DETECT IN. 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 protec-
tion from surface leakage currents. The detector input has internal
diode protection against static damage.
I/O. The I/O pin provides a terminal 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 s delay. The LED is suppressed when an
alarm is signaled from another interconnected unit. An inter-
nal NMOS device acts as a charge dump to aid in applications
involving a large (distributed) capacitance on the I/O pin. The
charge dump is activated only on the removal of a local alarm.
Alarm Circuitry. If smoke is detected, the oscillator period
changes to 40 ms and the horn is enabled. The horn output is 160
ms ON, and 80 ms OFF, typical. During the OFF time, smoke is
again checked and the circuit will inhibit further horn output if
smoke is not sensed. During smoke conditions, the low-battery-
warning is inhibited. The LED is driven at a 1 Hz rate, and will
only turn ON while the horn outputs are in the OFF state.
Testing. On power-up, all internal counters are reset. Internal
test circuitry allows for low-battery check by holding the
FEEDBACK and OSC CAP pins low during power-up, then
reducing VDD and monitoring HORN1. All functional tests can be
accelerated by driving OSC CAP with a 2 kHz square wave. The
10 ms strobe period must be maintained for proper operation of
the comparator circuitry.
Sensitivity Adjust. The detector sensitivity to smoke is set
internally by a voltage divider connected between VDD and VSS.
The sensitivity can be externally adjusted to the individual char-
acteristics of the ionization chamber by connecting a resistor, RS,
between the SENSITIVITY SET pin and +SUPPLY, or between
SENSITIVITY SET pin and –SUPPLY.
5
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
Smoke Detector with Interconnect and Timer
A5338
Timing Requirements: Nontimer Mode
(Circuit Shown in Typical Application)
1.67 s
10 ms
40 ms
Internal
Oscillator
24 Cycles
24 Cycles
30 Cycles
LED
LED Off
LED On
12 Cycles
HORN On
6 Cycles
6 Cycles
Internal
Smoke
Comparator
Ssmple
Low Battery
Warning
HORNx
HORN Off
Smoke
Chamber
Condition
V
> V
SENSITIVITY_SET
V
< V
(smoke)
V
> V
SENSITIVITY_SET
DETECT_IN
(no smoke)
DETECT_IN
SENSITIVITY_SET
DETECT_IN
(no smoke)
Dwg. WC-003
Timing Requirements: Timer Mode
(Circuit Shown in Typical Application)
OSC CAP
1.67 s
10 ms
Internal
Oscillator
232 Cycles
TIMER START
TIMER OUT
LED
Outputs Off (High Z)
6 Cycles
Dwg. WC-005-3
LED On
6
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
Smoke Detector with Interconnect and Timer
A5338
I/O Operation: V(IO) Input
Remote Alarm Mode
1.67 s
40 ms
Internal
Oscillator
4 Cycles
2 Cycles
HORN On
HORNx
HORN Off
I/O
HORN not self-completing
when in remote-only alarm
I/O Operation: V(IO) Output
Local Alarm Mode
Internal
Oscillator
HORN On
HORNx
HORN Off
78 Cycles
I/O
Dwg. WC-004
7
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
Smoke Detector with Interconnect and Timer
A5338
Package A, 16-pin DIP
.775 19.69
.735 18.67
A
.014 0.36
.008 0.20
B
16
.430 10.92
MAX
.280 7.11
.240 6.10
.300 .7.62
A
1
2
.195 4.95
.115 2.92
C
SEATING
PLANE
.015 2.92
MIN
Preliminary dimensions, for reference only
Dimensions in inches
.005 0.13
MIN
.100 .2.54
.150 3.81
.115 2.92
Metric dimensions (mm) in brackets, for reference only
(reference JEDEC MS-001 BB)
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
.070 1.78
.045 1.14
.022 .056
16X
.014 .036
A
Terminal #1 mark area
.010 [0.25] M
C
The products described here are manufactured under one or more U.S. patents or U.S. patents pending.
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit
improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the
information being relied upon is current.
Allegro products are not authorized for use as critical components in life-support devices or systems without express written approval.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use;
nor for any infringement of patents or other rights of third parties which may result from its use.
Copyright©2005 AllegroMicrosystems, Inc.
8
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
26110.1
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