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5368
SMOKE DETECTOR WITH INTERCONNECT AND TIMER
The A5368CA 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 A5368CA is supplied in a low-cost, 16-pin dual in-line plastic package. It is rated for continuous operation over the temperature range of 0C to +50C.
TIMER START I/O LOW-V SET TIMER OUT LED + SUPPLY TIMING RES. FEEDBACK 1 2 3 4 5 6 7 8 V SS V DD 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 26110.8*
OSC. & TIMING
HORN DRIVER
Dwg. PC-004
FEATURES
s s s s s s s s s
ABSOLUTE MAXIMUM RATINGS
(Voltages are referenced to VSS )
Supply Voltage Range, VDD ................................ -0.5 V to +15 V Reverse Battery (10.5 V) ....................... 20 s Input Voltage Range, VIN ........................ -0.3 V to VDD + 0.3 V Input Current, IIN ............................... 10 mA Operating Temperature Range, TA ..................................... 0C to +50C Storage Temperature Range, TS ............................... -55C to +125C
CAUTION: CMOS devices have input static protection but are susceptible to damage when exposed to extremely high static electrical charges.
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 & Control for Reduced Sensitivity Built-In Hysteresis Reduces False Triggering Temporal Horn Pattern
Always order by complete part number: A5368CA .
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
FUNCTIONAL BLOCK DIAGRAM AND TYPICAL APPLICATION
+ SUPPLY V 6 9V
DD
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 TIMER START
- +
- +
13
POWER-ON RESET
TIMING RES. 7 OSCILLATOR & TIMING OSC. CAP. 12 4 TIMER OUT +V
Dwg. FC-001B
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright (c) 1998, Allegro MicroSystems, Inc.
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
ELECTRICAL CHARACTERISTICS at TA = +25C, VDD = 9.0 V, VSS = 0 V, C12 = 0.1 F, R7 = 8.2 M (unless otherwise noted).
Test Characteristic Supply Voltage Range Detector Input Current Input Offset Voltage 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 Test Conditions Operating 0 to 40% RH, VIN = 0 to 9.0 V Active Guard Active Guard Detect Comparator No Alarm to Alarm Guard Amplifier Smoke Comparator to VSS to VSS No Alarm Alarm Oscillator Pulse Width Timer Period Low Voltage Threshold Sensitivity Adj. Voltage Horn Output Voltage 4 4 6 13 10-11 After Pin 1 High-to-Low, No Smoke TA = 0 to 50C V13/V DD, pin 13 open circuit IOUT = 16 mA, VDD = 9.0 V IOUT = 16 mA, VDD = 7.2 V IOUT = -16 mA, V DD = 9.0 V IOUT = -16 mA, V DD = 7.2 V Horn Output ON Time 10-11 Alarm (see figure, time "A") Low Battery Horn Output OFF Time 10-11 Alarm (see figure, time "B") Alarm (see figure, time "C") Low Battery Timer Start Logic Levels 1 VIH VIL Min. 6.0 -- -- -- -- 90 2.0 0.5 -- -- 1.34 32 8.0 8.0 7.2 48.5 -- -- 8.5 6.3 450 8.0 450 1350 32 4.5 -- Limits Typ. 9.0 -- -- -- -- 130 -- -- 10 500 1.67 40 10 10 -- 50 0.1 -- 8.8 -- 500 10 500 1500 40 -- -- Max. 12 1.0 100 100 50 170 VDD - 0.5 VDD - 2.0 -- -- 2.00 48 12 12 7.8 51.5 0.5 0.9 -- -- 550 12 550 1650 48 -- 2.5 Units V pA mV mV mV mV V V k k s ms ms min V % V V V V ms ms ms ms s V V
NOTE 1: NOTE 2:
Continued next page . . . Negative current is defined as coming out of (sourcing) the specified device pin. Alarm (Smoke) Condition is defined as V15 < V13; No Alarm (No Smoke) Condition as V15 > V13.
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
ELECTRICAL CHARACTERISTICS continued
Test Characteristic Timer Start Input Current Timer Out Output Current LED Output ON Current LED Output ON Time LED Output OFF Time Pin 1 4 5 5 5 Test Conditions VIN = 9.0 V VOUT = 0.5 V VDD = 7.2 V, VOUT = 1.0 V No Local Alarm; Not Latched No Alarm, In Standby No Alarm, Timer Mode I/O Current 2 No Alarm, VI/O = VDD - 2.0 V Alarm, VI/O = V DD - 2.0 V Charge Dump, VI/O = 1.0 V I/O Charge Dump Duration I/O Alarm Voltage I/O Delay Supply Current 2 2 2 6 After Local Alarm or Test External "Alarm" In "Alarm" Out VDD = 9.0 V, No Alarm, No Loads VDD = 12 V, No Alarm, No Loads Min. 20 500 10 8.0 32 8.0 25 -7.5 5.0 1.33 3.0 -- -- -- -- -- -- 10 40 10 -- -- -- 1.66 -- 3.0 5.0 -- Limits Typ. Max. 80 -- -- 12 48 12 60 -- -- 1.99 -- -- 9.0 12 Units A A mA ms s s A mA mA s V s A A
NOTE 1: NOTE 2:
Negative current is defined as coming out of (sourcing) the specified device pin. Alarm (Smoke) Condition is defined as V15 < V13; No Alarm (No Smoke) Condition as V15 > V13.
CIRCUIT DESCRIPTION
The A5368CA 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 nosmoke 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 VDD to an internal reference. Since very-low currents are used in the device, the oscillator capacitor at pin 12 should be a low-leakage type (PTFE, polystyrene, or polypropylene).
Detector Circuitry. When smoke is detected, 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 connections to pins 3 or 13. This provides hysteresis 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 0.5 s ON, 0.5 s OFF, 0.5 s ON, 0.5 s OFF, 0.5 s ON, 1.5 s OFF (temporal horn pattern). During the OFF time, smoke is 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.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
Sensitivity Adjust. The detector sensitivity to smoke is set internally by a voltage divider connected between VDD 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 VDD, or between pin 13 and VSS. 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 between pin 3 and VDD. The threshold can be decreased by connecting a resistor between pin 3 and VSS. 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. Timer. An internal timer is provided that can be used in various configurations to allow for a period of reduced smoke detector sensitivity ("hush"). When a high-to-low transition occurs at pin 1, the internal timer is reset, the timer mode enabled, and the circuit reset to a no alarm condition. The LED will flash at a 10 second 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 10-1/4 minute period (368 clock cycles). If the timer mode is not used, pin 1 should be tied low. 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 interconnected
TYPICAL APPLICATION
50 k
9V TIMER MODE
200 k
200 k
TO OTHER UNITS
1 200 2 NOTE 3 330 5 6 8.2 M 7 1 F 8 V SS V DD 3 4 LOGIC
16 15 14 OSC. & TIMING 13 12 11 10 9 0.1 F
PUSH TO TEST
NOTE 1
HORN DRIVER
1 M
200 k
0.001 F
NOTE 2
Dwg. EC-005A
NOTE 1: Use an external resistor to adjust sensitivity for a particular smoke chamber. NOTE 2: Select resistor to reduce sensitivity during timer mode. NOTE 3: A resistor to ground or VDD may be added to this pin to modify low battery voltage threshold.
unit. An internal NMOS device acts as a charge dump to aid in applications involving a large (distributed) capacitance on pin 2. The charge dump is activated only on the removal of a local alarm. 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 VDD and monitoring HORN1 (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 operation of the comparator circuitry.
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
TIMING DIAGRAMS IN TYPICAL APPLICATION
NON-TIMER MODE
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
24 CLOCK CYCLES
INTERNAL CLOCK
24 CLOCK CYCLES
19 CLOCK CYCLES
30 CLOCK CYCLES
LED
LED OFF
24 CLOCK CYCLES
LED ON
13 CLOCK CYCLES
SMOKE COMPARATOR
SAMPLE
12 CLOCK CYCLES
12 CLOCK CYCLES
36 CLOCK CYCLES
LOW BATTERY WARNING
HORN
HORN ON TIME "A"
HORN OFF TIME "B"
HORN OFF TIME "C"
SMOKE CHAMBER
V15 < V13 (SMOKE) V15 > V13 (NO SMOKE)
SHADED AND UNSHADED AREAS ARE DIFFERENT TIME SCALES
I/O CHARGE DUMP
I/O
73 CLOCK CYCLES
Dwg. WC-003-2
TIMER MODE
V12 OSC. CAP
1.67 s
10 ms
INTERNAL CLOCK
368 CLOCK CYCLES
TIMER START
TIMER OUT
6 CLOCK CYCLES
OUTPUTS OFF (HIGH Z)
LED
LED ON
END OF TIMER NOTIFICATION
HORN
I/O CHARGE DUMP
I/O
Dwg. WC-005-1
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
I/O OPERATION
REMOTE ALARM MODE NO LOW BATTERY 40 ms 1.67 s
INTERNAL CLOCK
12 CLOCK CYCLES
HORN
NO I/O CHARGE DUMP
V2 IN I/O
SHADED AND UNSHADED AREAS ARE DIFFERENT TIME SCALES
HORN CYCLE NOT SELF COMPLETING AFTER REMOTE OR LOCAL ALARM CONDITION IS REMOVED SINGLE HORN PULSE IN PROGRESS IS SELF COMPLETING AFTER LOCAL ALARM CONDITION IS REMOVED
LOCAL ALARM MODE NO LOW BATTERY
INTERNAL CLOCK
12 CLOCK CYCLES
HORN
72 CLOCK CYCLES
I/O CHARGE DUMP
V2 OUT I/O
Dwg. WC-004-1
5368 SMOKE DETECTOR WITH INTERCONNECT AND TIMER
Dimensions in Inches
(controlling dimensions)
9 0.014 0.008
16
0.430 0.280 0.240
MAX
0.300
BSC
1 0.070 0.045
0.100 0.775 0.735
BSC
8 0.005
MIN
0.210
MAX
0.015
MIN
0.150 0.115 0.022 0.014
Dwg. MA-001-16A in
Dimensions in Millimeters
(for reference only)
16 9 0.355 0.204
10.92 7.11 6.10
MAX
7.62
BSC
1 1.77 1.15
2.54 19.68 18.67
BSC
8 0.13
MIN
5.33
MAX
0.39
MIN
3.81 2.93 0.558 0.356
Dwg. MA-001-16A mm
NOTES: 1. Lead thickness is measured at seating plane or below. 2. Lead spacing tolerance is non-cumulative. 3. Exact body and lead configuration at vendor's option within limits shown.
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 design of its products. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000

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