A5358
Photoelectric Smoke Detector with Interconnect and Timer
Not for New Design
These parts are in production but have been determined to be NOT FOR
NEW DESIGN. This classification indicates that sale of this device is
currently restricted to existing customer applications. The device should
not be purchased for new design applications because obsolescence in
the near future is probable. Samples are no longer available.
Date of status change: October 1, 2022
Recommended Substitutions:
For existing customer transition, and for new customers or new applications, contact factory.
NOTE: For detailed information on purchasing options, contact your
local Allegro field applications engineer or sales representative.
Allegro MicroSystems reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a
product to accommodate changes in production capabilities, alternative product availabilities, or market demand. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for
its use; nor for any infringements of patents or other rights of third parties which may result from its use.
A5358
Photoelectric Smoke Detector with Interconnect and Timer
FEATURES AND BENEFITS
DESCRIPTION
▪ Low average standby current for long battery life
▪ Interconnect up to 50 detectors
▪ Piezoelectric horn driver
▪ Low battery detection (all internal)
▪ Chamber sensitivity test and alarm
▪ Power-on reset (POR)
▪ Internal timer and control for reduced sensitivity mode
▪ Built-in circuits to reduce false triggering
▪ 6 to 12 V operating range
▪ ESD protection circuitry on all pins
The A5358 is a low-current BiCMOS circuit providing all of
the required features for a photoelectric type smoke detector.
This device can be used with an infrared photoelectric chamber
to sense scattered light from smoke particles. A networking
capability allows as many as 50 units to be interconnected so
that if any unit senses smoke all units will sound an alarm.
Special features are incorporated in the design to facilitate
calibration and testing of the finished detector. The device is
designed for applications that comply with European Standard
EN 14604 and British Standard BS 5446, Part 1.
A variable-gain photoamplifier can be directly interfaced to
an infrared emitter-detector pair. The amplifier gain levels
are determined by two external capacitors and are internally
selected depending on the operating mode. Low gain is selected
during standby and timer modes. During a local alarm, this low
gain is increased (internally) by approximately 10% to reduce
false triggering. High gain is used during pushbutton test and
to periodically monitor the chamber sensitivity during standby.
PACKAGES:
16-pin DIP
(Package A)
The internal oscillator and timing circuitry keep standby power
to a minimum by sensing for smoke for only 100 µs every 10 s.
A special three-stage–speedup sensing scheme is incorporated
to minimize the time to an audible alarm and also to reduce
false triggering. Chamber sensitivity is periodically monitored,
and two consecutive cycles of degraded sensitivity are required
for a warning signal (chirp) to occur.
16-pin SOICW
(Package LW)
The A5358 is supplied in a 16-pin dual in-line plastic package
(suffix A), and for surface mount, a 16-pin SOICW (suffix LW).
The lead (Pb) free versions (suffix –T) have 100% matte-tin
leadframe plating. The devices are rated for continuous operation
over the temperature range of –25°C to 75°C.
Not to scale
Typical Application Diagram
VDD
0.047 µF
Rx1
A
8.2 kΩ
5 kΩ
Rx2
1
2
4.7 kΩ
4700 pF
560 Ω
200 kΩ
C1
C2
3
DETECT
4 STROBE
5
VDD
A5358
TEST 16
HUSH
VSS
TIMING RES
1 kΩ
6
Smoke
Chamber
100 µF
To / from
other units
26110.10-DS, Rev. 12
MCO-0000916
22 Ω
7
8
220 Ω
IRED
I/O
HORN1
OSC CAP
LED
15
14
9V
22 µF
Push-to-Test
1500 pF
13
12
Red LED
B
10 MΩ
100 kΩ
330 Ω
220 kΩ C
1000 pF
C
1.5 MΩ C
Connect to allow timer mode
("hush") operation
B Connect HUSH to VSS
to disable timer mode
C Value of component can vary,
based on the piezoelectric horn used
11
10
FEEDBACK
HORN2 9
A
Piezo Horn
October 1, 2022
A5358
Photoelectric Smoke Detector with Interconnect and Timer
SELECTION GUIDE
Part Number
Pb-free
Package
Packing
A5358CA
–
16-pin DIP through hole
25 pieces / tube
A5358CA-T
Yes
16-pin DIP through hole
25 pieces / tube
A5358CLWTR-T
Yes
16-pin SOICW surface mount
1000 pieces / reel
ABSOLUTE MAXIMUM RATINGS*
Characteristic
Symbol
Notes
Rating
Units
Supply Voltage Range
VDD
Referenced to VSS
–0.5 to 15
V
Input Voltage Range
VIN
Referenced to VSS
–0.3 to VDD+0.3
V
Input Current
IIN
10
mA
Operating Ambient Temperature Range
TA
–25 to 75
°C
TJ(max)
150
°C
Tstg
–55 to 125
°C
Maximum Junction Temperature
Storage Temperature Range
*CAUTION: BiCMOS devices have input static protection but are susceptible to damage if exposed to extremely high static electrical
charges.
THERMAL CHARACTERISTICS
Characteristic
Package Thermal Resistance
Symbol
RθJA
Value
Units
Package A, on 4-layer PCB based on JEDEC standard
Test Conditions*
38
°C/W
Package LW, on 4-layer PCB based on JEDEC standard
48
°C/W
*Additional thermal information available on Allegro website.
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
2
A5358
Photoelectric Smoke Detector with Interconnect and Timer
PINOUT DIAGRAM AND TERMINAL LIST
Terminal List Table
Pinout Diagrams
Package A
C1 1
16 TEST
C2 2
15 HUSH
DETECT 3
14 VSS
STROBE 4
13 TIMING RES
Number
Name
Function
1
C1
Sets photoamplifier gain in supervisory mode
2
C2
Sets photoamplifier gain in standby mode
3
DETECT
Photoamplifier input
4
STROBE
Strobed supply (VDD – 5 V) for photoamplifier low-side
reference
VDD 5
12 OSC CAP
5
VDD
Positive supply voltage
IRED 6
11 LED
6
IRED
Output to smoke chamber IR LED driver
7
I/O
Input-output to interconnected detectors
8
HORN1
Output for driving piezoelectric horn
Complementary output for driving piezoelectric horn
10 FEEDBACK
I/O 7
9 HORN2
HORN1 8
Package LW
C1 1
16 TEST
C2 2
9
HORN2
10
FEEDBACK
11
LED
Input for driving piezoelectric horn
Output to drive visible LED
15 HUSH
12
OSC CAP
DETECT 3
14 VSS
STROBE 4
13 TIMING RES
13
TIMING RES
14
VSS
15
HUSH
Input for photoamplifier timer mode reference; can also
disable timer mode
16
TEST
Enables push-to-test mode and diagnostic test/calibration
mode; starts timer mode, if enabled
VDD 5
12 OSC CAP
IRED 6
11 LED
I/O 7
HORN1 8
10 FEEDBACK
9 HORN2
Connection for capacitor to set clock frequency
Connection for resistor to set clock frequency
Negative supply voltage
Allegro MicroSystems
955 Perimeter Road
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3
A5358
Photoelectric Smoke Detector with Interconnect and Timer
FUNCTIONAL BLOCK DIAGRAM
I/O
+Supply
VDD
9V
FEEDBACK
VDD
Band-gap
Reference
HORN2
+
_
HORN1
Low Battery
LED
Logic
VDD
Photoamp
+
_
DETECT
C1
Power-On
Reset
TIMING RES
C2
Oscillator
and Timing
STROBE
VDD
VDD
OSC CAP
VSS
IRED
–Supply
HUSH
TEST
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
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4
A5358
Photoelectric Smoke Detector with Interconnect and Timer
DC ELECTRICAL CHARACTERISTICS: Valid at TA = –25°Cto 75°C [1]. VSS = 0 V, in typical application (unless otherwise noted)
Characteristic
Supply Voltage Range
Operating Supply Current
Low-Level Input Voltage
High-Level Input Voltage
Symbol
Test Conditions
VDD
IDD
Input Leakage Low
IIL
Low-Level Output Voltage
High-Level Output Voltage
Strobe Output Voltage
Line Regulation
VOL
VOH
VST
ΔVST(ΔVDD)
Strobe Temperature
Coefficient
αST
IRED Output Voltage
VIRED
Max.
Units
6.0
–
12
V
5
12
–
–
9
μA
During STROBE on, IRED off, configured per
typical application
5
12
–
–
2.0
mA
During STROBE on, IRED on, configured per
typical application
5
12
–
–
3.0
mA
VIN = VDD, STROBE active, OSC CAP = VDD
VIN = VDD
VIN = VSS
VIN = VDD
IIN
Typ. [2]
–
VIN = VST, STROBE active, OSC CAP = VDD
Input Pull-Down Current
Min.
5
VIH
IIH
VDD
Average in standby mode, configured per
typical application
VIL
Input Leakage High
Test Pin
No local smoke, VIN = VDD
7
9
–
–
1.5
V
10
9
–
–
2.7
V
16
9
–
–
7.0
V
15
9
–
–
0.5
V
7
9
3.2
–
–
V
10
9
6.3
–
–
V
16
9
8.5
–
–
V
15
9
1.6
–
–
V
1, 2
12
–
–
100
nA
3, 10,
12
12
–
–
100
nA
1, 2, 3
12
–
–
–100
nA
10, 12
12
–
–
–100
nA
15, 16
12
–
–
–1.0
μA
16, 15
9
0.25
–
10
μA
7
9
20
–
80
μA
No local smoke, VIN = 17 V
7
12
–
–
140
μA
IO = 10 mA
11
6.5
–
–
0.6
V
IO = 16 mA
8, 9
6.5
–
–
1.0
V
IO = 5 mA
13
6.5
–
0.5
–
V
IO = –16 mA
8, 9
6.5
5.5
–
–
V
–
–
V
Inactive, IO = –1 μA
4
12
VDD –
0.1
Active, IO = 100 to 500 μA
4
9
VDD –
5.25
–
VDD –
4.75
V
Active, VDD = 6 to 12 V
4
–
–
–60
–
dB
VDD = 6 to 12 V
4
–
–
0.01
–
%/°C
Inactive, IO = 1 μA, TA = 25°C
6
12
–
–
0.1
V
Active, IO = –6 mA, TA = 25°C
6
9
2.85
3.1
3.35
V
Continued on the next page…
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5
A5358
Photoelectric Smoke Detector with Interconnect and Timer
DC ELECTRICAL CHARACTERISTICS (continued): Valid at TA = –25°Cto 75°C [1]. VSS = 0 V, in typical application (unless otherwise noted)
Characteristic
Line Regulation
IRED Temperature Coefficient
Symbol
ΔVIRED(ΔVDD)
αIRED
Test Conditions
Test Pin
Active, VDD = 6 to 12 V
6
VDD = 6 to 12 V
6
VDD
Min.
Typ. [2]
Max.
Units
–
–35
–
dB
–
–
0.40
–
%/°C
High-Level Output Current
IOH
VDD = Alarm, I/O active,VO = VDD – 2 V
7
9
–4.0
–
–
mA
OFF Leakage Current High
IOZ
VO = VDD
11, 13
12
–
–
1.0
μA
IOZ
VO = VSS
11, 13
12
–
–
–1.0
μA
5
–
6.9
7.2
7.5
V
OFF Leakage Current Low
Low-Battery Alarm Threshold
Common Mode Voltage
Smoke Comparator
Reference Voltage
[1] Limits
VDD(th)
VIC
Any alarm condition
1, 2, 3
–
VDD – 4
–
VDD – 2
V
VREF
Any alarm condition
Internal
–
VDD –
3.7
–
VDD –
3.3
V
over the operating temperature range are based on characterization data. Characteristics are production tested at 25°C only.
values are at 25°C and are given for circuit design information only.
[2] Typical
AC ELECTRICAL CHARACTERISTICS: Valid at TA = –25°Cto 75°C [1]. VSS = 0 V, in typical application (unless otherwise noted)
Characteristic
Oscillator Period
LED Pulse Period
LED Pulse Width
STROBE Pulse Period
STROBE Pulse Width
Symbol
Test Conditions
tosc
Test Pin
VDD
Min.
Typ. [2]
Max.
Units
12
9
9.4
10.5
11.5
ms
tled1
No local or remote smoke
11
9
39
–
48
s
tled3
Local smoke
11
9
0.60
0.67
0.74
s
–
s
s
tled4
Remote smoke only
11
9
–
No
LED
Pulses
tled6
Pushbutton test, induced alarm
11
9
0.60
0.67
0.74
tled7
Timer mode, no alarm
11
9
9.67
10.8
11.8
s
11
9
9.5
–
11.5
ms
tw(led)
tst1
No local or remote smoke
4
9
9.6
–
11.9
s
tst2
After 1 of 3 valid samples
4
9
2.42
2.70
2.96
s
tst3
After 2 of 3 valid samples and during local
alarm
4
9
1.21
1.34
1.47
s
tst4
Remote smoke only
4
9
9.67
10.8
11.8
s
tst5
Chamber test or low battery test, no local
alarm
4
9
38.9
–
47.1
s
tst6
Pushbutton test, induced alarm
4
9
300
336
370
ms
4
9
9.5
–
11.5
ms
tw(st)
Continued on the next page…
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
6
A5358
Photoelectric Smoke Detector with Interconnect and Timer
AC ELECTRICAL CHARACTERISTICS (continued): Valid at TA = –25°Cto 75°C [1]. VSS = 0 V, in typical application (unless otherwise noted)
Characteristic
IRED Pulse Period
Symbol
Test Conditions
Test Pin
VDD
Min.
Typ. [2]
Max.
Units
tired1
No local or remote smoke
6
9
9.6
–
11.9
s
tired2
After 1 of 3 valid samples
6
9
2.42
2.70
2.96
s
tired3
After 2 of 3 valid samples and during local
alarm
6
9
1.21
1.34
1.47
s
tired4
Remote smoke only
6
9
9.67
10.8
11.8
s
tired5
Chamber test, no local alarm
6
9
38.9
–
47.1
s
tired6
Pushbutton test, induced alarm
6
9
300
336
370
ms
6
9
94
–
116
μs
IRED Pulse Width
tw(ired)
IRED Rise Time
tr(ired)
10% to 90%
6
–
–
30
μs
IRED Fall Time
tf(ired)
90% to 10%
6
–
–
200
μs
I/O to Active Delay
td(io)
Local alarm
7
9
–
0
–
s
Rising Edge on I/O to Alarm
tr(io)
No local alarm
7
9
–
–
13 ×
tOSC
s
Horn Warning Pulse Period
thorn
Low battery or degraded chamber sensitivity
8, 9
9
38.9
–
47.1
s
Horn Warning Pulse Width
tw(horn)
Low battery or degraded chamber sensitivity
8, 9
9
9.5
–
11.5
ms
Horn On-Time
ton(horn)
Local or remote alarm
8, 9
9
–
252
–
ms
Horn Off-Time
toff(horn)
Local or remote alarm
8, 9
9
–
84
–
ms
[1] Limits
over the operating temperature range are based on characterization data. Characteristics are production tested at 25°C only.
values are at 25°C and are given for circuit design information only.
[2] Typical
Allegro MicroSystems
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A5358
Photoelectric Smoke Detector with Interconnect and Timer
Pin and Circuit Description
(In Typical Application)
C1 Pin
A capacitor connected to this pin determines the gain, Ae, of
the photoamplifier during the push-to-test mode and during the
chamber monitor test. A typical capacitor value for this high-gain
(supervisory) mode is 0.047 μF, but it should be selected based
on the photochamber background reflections reaching the detector and the desired level of sensitivity. Ae = 1 + (C1 / 10), where
C1 is in pF. Ae should not exceed 10,000 and thus C1 should
not exceed 0.1 μF. Coupling of other signals to the C1, C2, and
DETECT inputs must be minimized.
C2 Pin
A capacitor connected to this pin determines the gain, Ae, of the
photoamplifier during standby. A typical capacitor value for this
low-gain mode is 4700 pF, but it should be selected based on
a specific photochamber and the desired level of sensitivity to
smoke. Ae = 1 + (C2 / 10), where C2 is in pF. Ae should not exceed
10,000 and thus C2 should not exceed 0.1 μF. This gain increases
by a nominal 10% after a local alarm is detected (three consecutive detections). A resistor must be installed in series with the C2
capacitor.
DETECT Pin
This is the input to the photoamplifier and is connected to the
cathode of the photodiode. The photodiode is operated at zero bias
and should have low dark leakage current and low capacitance. A
shunt resistor must be installed in parallel with the photodiode.
STROBE Pin
This output provides a strobed, regulated voltage of VDD – 5 V.
The minus side of all internal and external photoamplifier circuitry is referenced to this pin.
VDD Pin
This pin is connected to the positive supply potential and can
range from 6 to 12 V with respect to VSS.
IRED Pin
This output provides a pulsed base current for the external NPN
transistor, which drives the IR emitter. Its beta should be greater
than 100. To minimize noise impact, the IRED output is not
active when the horn and visible LED outputs are active.
I/O Pin
A connection at this pin allows multiple smoke detectors to be
interconnected. If any single unit detects smoke, its I/O pin is
driven high, and all connected units will sound their associated
horns.
As an input, the I/O is sampled every fourth clock cycle (nominally 42 ms). When the I/O pin is driven high by another device,
three consecutive samples with I/O high plus one additional
cycle (nominally 10.5 ms) are required to cause an alarm. If the
I/O falls below its threshold at any time during those (nominally)
95 ms, an internal latch is reset and there will not be an alarm.
Thus, depending on when during the (nominally) 42 ms sample
cycle I/O is initially forced high, the I/O must remain high for a
minimum of (nominally) 95 to 137 ms to cause an alarm. This
filtering provides significant immunity to I/O noise.
The LED is suppressed when an alarm is signaled from an interconnected unit, and any local alarm condition causes this pin to
be ignored as an input. This pin has an on-chip pull-down device
and must be left unconnected if not used. In the application,
there should be a series current-limiting resistor to other smoke
alarms.
HORN1, HORN2, and FEEDBACK Pins
These three pins are used with a self-resonating piezoelectric
transducer and horn-starting external passive components. The
output HORN1 is connected to the piezo metal support electrode. The complementary output, HORN2, is connected to the
ceramic electrode. The FEEDBACK input is connected to the
feedback electrode. If the FEEDBACK pin is not used, it must
be connected to VSS.
LED Pin
This open-drain NMOS output is used to directly drive a visible
LED. The load for the low-battery test is applied to this output.
If an LED is not used, it should be replaced with an equivalent
resistor (typically 500 to 1000 Ω) such that the battery loading remains about 10 mA. The low-battery test does not occur
coincident with any other test or alarm signal. The LED also
indicates detector status as follows (with component values as in
the typical application, all times nominal):
Condition
Pulse Occurrence
Standby
Every 43 seconds
Local Smoke
Every 0.67 seconds
Remote Alarm
No pulses
Test Mode
Every 0.67 seconds
Timer Mode
Every 10 seconds
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8
A5358
Photoelectric Smoke Detector with Interconnect and Timer
OSC CAP (Oscillator Capacitor) Pin
A capacitor between this pin and VDD, along with a parallel
resistor, forms part of a two-terminal oscillator and sets the internal clock low time. With component values shown, this nominal
time is 10.4 ms and essentially the oscillator period. The internal
clock low time can be calculated by:
Tlow = 0.693 × ROSCCAP × COSCCAP .
TIMING RES (Timing Resistor) Pin
A resistor between this pin and OSC CAP is part of the twoterminal oscillator and sets the internal clock high time, which is
also the IRED pulse width. With component values shown, this
time is nominally 105 μs. The internal clock high time can be
calculated by:
Thigh = 0.693 × RTIMINGRES × COSCCAP .
VSS Pin
This pin is connected to the negative supply potential (usually
ground).
HUSH Pin
This input pin has an internal pull-down device and serves two
purposes in standby mode. It serves to enable/disable entering
the internal 10-minute (nominal) “hush” timer mode, and also
as the reference for the smoke comparator during timer mode.
When the voltage on this pin is greater than 1.5 V, entering timer
mode is enabled, and a high-to-low transition on TEST resets
and starts timer mode. If use of timer mode is not desired, this
pin can be connected to VSS or left open, and a voltage of less
than 0.5 V on the pin will disable timer mode. During timer
mode, the smoke comparator reference is established by a resistive divider (Rx1 and Rx2) between the VDD and STROBE
pins and allows the detector to operate with reduced sensitivity
during timer mode. This allows the user to hush alarms caused
by nuisance smoke or steam (such as from cooking). When not
in timer mode, the smoke comparator reference is set internally
to approximately VDD – 3.5 V.
TEST Pin
This pin has an internal pull-down device and is used to manually invoke two test modes and timer mode.
Push-to-Test mode is initiated by a voltage greater than approximately VDD – 0.5 V on this pin (usually the depression of a
normally-open pushbutton switch to VDD). After one oscillator cycle, the amplifier gain is increased by internal selection
of C1 so that background reflections in the smoke chamber can
be used to simulate a smoke condition, and IRED pulses every
336 ms (nominal). After the third IRED pulse (three consecu-
tive simulated smoke conditions), the successful test activates
the horn drivers and the I/O pin, and the LED blinks once every
0.67 s. If the test fails, the LED will not blink, the horn will not
sound, and the I/O pin will remain low. When the pushbutton is
released, the input returns to VSS due to the internal pull down.
After one oscillator cycle, the amplifier gain returns to normal,
and after three additional IRED pulses (less than one second), the
device exits this mode and returns to standby. This high-to-low
transition on TEST also resets and starts the 10-minute (nominal)
“hush” timer mode, if the mode is enabled via the HUSH pin.
Diagnostic Test/Calibration Mode is available to facilitate
calibration and test of the IC and the assembled detector. It is
initiated by pulling TEST below VSS by continuously drawing
400 μA from the pin for at least one clock cycle on OSC CAP.
The current should not exceed 800 μA and under these conditions, TEST pin voltage will clamp at approximately 250 mV
below VSS. One option is to connect TEST to a –5 V supply
through a 12 kΩ resistor. In this mode, certain device pins are
Table 1. Alternate Pin Configuration During Diagnostic Test/
Calibration Mode
Pin Name
Alternate Configuration
I/O
Disabled as an output. A logic high on this pin places the
photoamplifier output on pin C1 or C2 as determined by
the HUSH pin. The amplifier output appears as pulses.
HUSH
If the I/O pin is high, this pin controls the amplifier gain
capacitor. If this pin is low, normal gain is selected,
and the amplifier output is on pin 1. If this pin is high,
supervisory gain is selected and the amplifier output is
on pin C2.
NOTE: If I/O is low, four rising edges on this pin will
cause the device to exit diagnostic/calibration mode and
enter an Allegro-defined test mode.
FEEDBACK
If the I/O pin is high and the HUSH pin is low (normal
gain), taking this pin to a high logic level increases the
amplifier gain by ≈10% (hysteresis).
OSC CAP
This pin may be driven by an external clock source.
Driving this pin low and high drives the internal clock low
and high. The external RC network may remain intact.
HORN1
This pin is reconfigured as the smoke integrator output.
Three consecutive smoke detections will cause this pin
to go high and three consecutive no-smoke detections
cause this pin to go low.
LED
This pin becomes a low-battery indicator. The open-drain
NMOS output is normally off. If VDD falls below the lowbattery threshold, the output turns on.
Allegro MicroSystems
955 Perimeter Road
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9
A5358
Photoelectric Smoke Detector with Interconnect and Timer
reconfigured as described in table 1. The IRED pulse rate is
increased to one pulse every OSC CAP cycle and the STROBE
pin is always active. To exit this mode, the TEST pin should be
floated, or returned to VSS, for at least one OSC CAP cycle.
Alarm Indications
Alarm conditions include: local smoke detection, a remote
alarm, low battery, or degraded chamber sensitivity. These are
indicated by a combination of horn and LED signals, which continue until the alarm condition is resolved. A local alarm always
overrides a remote alarm, and a local or remote alarm will inhibit
warning signals for low battery or degraded chamber.
During a local or a remote alarm condition, the horn output is a
continuous modulated tone, nominally: 252 ms on, 84 ms off.
The visible LED distinguishes a local alarm from a remote alarm.
During a local alarm, the LED blinks every 0.67 seconds (nominally), but during a remote alarm, the LED is disabled and does
not blink.
The degraded-chamber test occurs periodically (nominally
every 43 seconds). During this test, the gain of the photoamplifier is switched to the high (supervisory) level, set by C1. The
device expects that the photodiode will receive enough reflected
background light in the chamber to cause an alarm condition.
If a faulty, dirty, or obstructed chamber prevents this for two
consecutive tests, the device signals degraded chamber with one
short (nominally 10 ms) horn chirp every 43 seconds, essentially
halfway between LED flashes. The condition is resolved when
the chamber is either cleared or cleaned.
The low-battery test also occurs periodically (also nominally
every 43 seconds, but offset from the degraded-chamber test).
During this test, the load of the LED is applied to the battery, and a resistive divider off VDD is compared to an internal
band-gap reference. If VDD is below the threshold, the device
signals low battery with one short (nominally 10 ms) horn chirp
every 43 seconds, occurring almost simultaneously with the
visible LED flash. The condition is resolved when the battery is
replaced.
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
10
A5358
Photoelectric Smoke Detector with Interconnect and Timer
Timing Diagrams
(Not to Scale)
Standby Mode
Internal Clock
Photo Sample
tr(ired)
Test event
OSC CAP Pin
90%
50%
10%
tf(ired)
tw(ired)
tosc
tst1, tired1
tled1, tst5
Low-Battery Test
tst5, tired5
Chamber Test
tw(st)
STROBE Pin
IRED Pin
LED Pin
LED off (High-Z)
LED on
tw(led)
Low Battery Condition
(Low battery)
VDD Pin
Low-Battery Test
Horn Enable
Failed “test period”
thorn
tw(horn)
LED Pin
LED on
LED off
(High-Z)
Chirps occur at the end of a failed “test period,” and are nearly coincident with LED flashes
Degraded Chamber Condition
Chamber
Sensitivity
(Degraded chamber)
Chamber Test
thorn
Horn Enable
tw(horn)
LED Pin
LED on
LED off
(High-Z)
Chirps occur after 2 consecutive failed tests, and are offset from LED flashes and from chirps that indicate failure of low-battery tests
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
11
A5358
Photoelectric Smoke Detector with Interconnect and Timer
Local Smoke Detection Alarm Condition
1st strobe with smoke
3rd strobe with smoke
3rd strobe without smoke
IRED Pin
tst2,ired2
tw(st)
tst3,ired3
STROBE Pin
tw(led)
tled3
tst 3,ired3
LED Pin
ton(horn)
toff(horn)
Horn Enable
(Output)
I/O Pin
Remote Alarm Condition
tw(st)
tst4,ired4
STROBE Pin
LED Pin
ton(horn)
toff(horn)
Horn Enable
tr(io)
I/O Pin
(Input)
Test Alarm Mode
STROBE Pin
tw(st)
tst 6,ired6
LED Pin
tw(led)
tled6
TEST Pin
ton(horn)
toff(horn)
Horn Enable
I/O Pin
(Output)
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
12
A5358
Photoelectric Smoke Detector with Interconnect and Timer
Package A, 16-Pin DIP
19.05 ±0.25
0.25
16
6.35
A
1
+0.10
–0.05
+0.76
–0.25
7.62 BSC
10.92 MAX
2
A
Terminal #1 mark area
Branded Face
3.30
+1.65
–0.38
0.38 MIN
2.54 BSC
0.13 MIN
16 × 0.46±0.10
0.25 M C
SEATING
PLANE
C
5.33 MAX
3.30
+0.51
–0.38
For Reference Only; not for tooling use
(reference Allegro DWG-0000370 or JEDEC MS-001BB)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
+0.25
1.52
–0.38
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
13
A5358
Photoelectric Smoke Detector with Interconnect and Timer
Package LW, 16-Pin SOICW
For Reference Only – Not for Tooling Use
(Reference Allegro DWG-0000388, Rev. 1 and JEDEC MS-013AA)
NOT TO SCALE
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
8°
0°
10.21 ±0.10
16
9° ±2°
R0.76 ±0.13
7.50 ±0.10
0.32
0.23
10.31 ±0.20
A
0.76 ±0.25
1.40 REF
1
2
Branded Face
0.25 BSC
SEATING PLANE
16×
C
2.54 ±0.10
0.10
C
GAUGE PLANE
SEATING
PLANE
0.30
0.10
1.27 BSC
0.41 ±0.05
0.65
1.27
16
2.25
9.50
1
B
2
PCB Layout Reference View
A
Terminal #1 mark area
B
Reference land pattern layout (reference IPC7351 SOIC127P600X175-8M);
all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
14
A5358
Photoelectric Smoke Detector with Interconnect and Timer
Revision History
Number
Date
10
July 10, 2020
Minor editorial updates
Description
11
July 7, 2022
Updated package drawings (pages 12-13) and minor editorial updates
12
October 1, 2022
Changed product status: Not for new design
The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889;
5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending.
Copyright 2022, Allegro MicroSystems.
Allegro MicroSystems 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’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for its use; nor
for any infringement of patents or other rights of third parties which may result from its use.
Copies of this document are considered uncontrolled documents.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
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