5349 ALLEGRO
Document overview
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Technical content
Always order by complete part number:A5349CA . AC SMOKE DETECTOR WITH INTERCONNECT AND TIMER The A5349CA 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 safety or security applications. The A5349CA 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.
FEATURES
n Interconnect Up to 125 Detectors n Piezoelectric Horn Driver n Guard Outputs for Detector Input n Low Supply Detection n Power-ON Reset n Internal Timer & Control for Reduced Sensitivity n Built-In Hysteresis Reduces False Triggering ABSOLUTE MAXIMUM RATINGS (Voltages are referenced to VSS) Supply Voltage Range, Input Voltage Range, Operating Temperature Range, Storage Temperature Range, CAUTION: CMOS devices have input static protection but are susceptible to damage when exposed to extremely high static electrical charges. LOGIC OSC. & TIMING HORN DRIVER GUARD DETECT. IN GUARD SENSITIVITY SET OSC. CAP. HORN HORN – SUPPLY TIMER START I / O LOW-V SET TIMER OUT LED + SUPPLY TIMING RES. FEEDBACK V DD Dwg. PC-004 V SS Data Sheet 26110.4 5349
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000 5349 AC SMOKE DETECTOR with INTERCONNECT and TIMER LOW-V SET – SUPPLY + SUPPLY I / O TIMING RES. FEEDBACK DETECT. IN OSC. CAP. POWER-ON RESET OSCILLATOR & TIMING LOGIC SENSITIVITY SET GUARD GUARD HORN 1 HORN 2 LED TIMER OUT TIMER START V DD 14 15 16 V DD VSS Dwg. FC-005A FUNCTIONAL BLOCK DIAGRAM AND TYPICAL APPLICATION Copyright © 1995, Allegro MicroSystems, Inc.
ELECTRICAL CHARACTERISTICS at TA = +25°C, VDD = 9.0 V, VSS = 0 V, C12 = 0.1 µF, R7 = 8.2 MΩ (unless otherwise noted). 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 —1 0— k Ω 16 to V SS — 500 — k Ω Oscillator Period 12 No Alarm 1.34 1.67 2.00 s Alarm 32 40 48 ms Oscillator Pulse Width 4 8.0 10 12 ms Timer Period 4 After Pin 1 High-to-Low, No Smoke 8.0 10 12 min Low Voltage Threshold 6 T A = 0 to 50°C 7.2 — 7.8 V Sensitivity Adj. Voltage 13 V 13 / VDD , pin 13 open circuit 48.5 50 51.5 % Horn Output Voltage 10-11 I OUT = 16 mA, VDD = 9.0 V — 0.1 0.5 V IOUT = 16 mA, VDD = 7.2 V — — 0.9 V IOUT = -16 mA, VDD = 9.0 V 8.5 8.8 — V IOUT = -16 mA, VDD = 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 Timer Start Logic Levels 1 V IH 3.5 — — V VIL — — 1.5 V Timer Start Input Current 1 V IN = 9.0 V 20 — 80 µA Timer Out Output Current 4 V OUT = 0.5 V 500 — — µA Test NOTE 1: Negative current is defined as coming out of (sourcing) the specified device pin. NOTE 2: Alarm (Smoke) Condition is defined as V15 < V13; No Alarm (No Smoke) Condition as V15 > V13. Continued next page . . . 5349 AC SMOKE DETECTOR with INTERCONNECT and TIMER
Worcester, Massachusetts 01615-0036 (508) 853-5000 5349 AC SMOKE DETECTOR with INTERCONNECT and TIMER LED Output ON Current 5 V DD = 7.2 V, VOUT = 1.0 V 10 — — mA LED Output ON Time 5 Local Alarm constant OFF — Timer Mode, No Alarm — 8.35 — s LED Output OFF Time 5 No Alarm, In Standby constant ON — No Alarm, Timer Mode After Pin 1 High-to-Low — 1.67 — s I/O Current 2 No Alarm, V I/O = VDD – 2.0 V 25 — 60 µA Alarm, VI/O = VDD – 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 µA VDD = 12 V, No Alarm, No Loads — — 12 µA Limits Characteristic Pin Test Conditions Min. Typ. Max. Units Test ELECTRICAL CHARACTERISTICS continued NOTE 1: Negative current is defined as coming out of (sourcing) the specified device pin. NOTE 2: Alarm (Smoke) Condition is defined as V15 < V13; No Alarm (No Smoke) Condition as V15 > V13. CIRCUIT DESCRIPTION The A5349CA 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), a check is made for low supply by comparing V DD 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 in- crease 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.
OSC. & TIMING HORN DRIVER V DD Dw g. EC -005-1A V SS NOTE 2 200 kW 50 kW 200 kW 200 W 8.2 MW 1 mF 0.1 mF 1 MW 200 kW PUSH TO TEST 0.001 mF 330 W + SUPPLY 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-supply alarm is inhibited. LED. The LED is continuously ON during the standby mode indicating the unit is receiving power. During a remote alarm condition the LED remains ON. The LED is OFF during a local alarm condition. Sensitivity Adjust. The detector sensitivity to smoke is set internally by a voltage divider connected between V DD and VSS . 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 VSS . Low Supply. The low supply threshold is set internally by a voltage divider connected between V DD and VSS . The threshold can be increased by connecting a resistor between pin 3 and V DD . The threshold can be de- creased by connecting a resistor between pin 3 and V SS . The supply voltage level is checked every 40 seconds. Timer. An internal timer is provided that can be used in various configurations to allow for a period of reduced smoke detector sensitiv- ity (“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 in- creased 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 TYPICAL APPLICATION 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 V DD may be added to this pin to modify low battery voltage threshold. NOTE 4: Reverse supply protection must be supplied externally. sound their associated horns after a nominal 3 second delay. The LED remains ON when an alarm is signaled from an interconnected unit and a local smoke condition does not exist. 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 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. 5349 AC SMOKE DETECTOR with INTERCONNECT and TIMER
Worcester, Massachusetts 01615-0036 (508) 853-5000 5349 AC SMOKE DETECTOR with INTERCONNECT and TIMER TIMING DIAGRAMS IN TYPICAL APPLICATION NON-TIMER MODE Dwg. WC-006 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
12 CLOCK CYCLES 6 CLOCK
6 CLOCK
OSC. CAP INTERNAL CLOCK LED HORN ON TIMER START TIMER OUT
6 CLOCK CYCLES
368 CLOCK CYCLES
1.67 s OFFON Dwg. WC-007
Dwg. WC-004 HORN ON OFF HORN NOT SELF COMPLETING WHEN IN REMOTE ONLY ALARM INTERNAL CLOCK HORN V2 IN I/O
4 CYCLES 2 CYCLES
40 ms 1.67 s
72 CLOCK CYCLES
Worcester, Massachusetts 01615-0036 (508) 853-5000 5349 AC SMOKE DETECTOR with INTERCONNECT and TIMER Dimensions in Inches (controlling dimensions) Dimensions in Millimeters (for reference only) 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. 0.355 0.204 7.62 BSC Dwg. MA-001-16A mm 10.92 MAX 1 8 7.11 6.10 5.33 MAX 1.77 1.15 0.39 MIN 0.558 0.356 2.54 BSC 0.13 MIN 3.81 2.93 19.68 18.67 0.014 0.008 0.300 BSC Dwg. MA-001-16A in 0.430 MAX 1 8 0.280 0.240 0.210 MAX 0.070 0.045 0.015 MIN 0.022 0.014 0.100 BSC 0.005 MIN 0.150 0.115 0.775 0.735