Data Sheet 26110.3 5348 SMOKE DETECTOR WITH INTERCONNECT AND TIMER TIMER START 1 I/O 2 LOW-V SET 3 TIMER OUT 4 LED 5 + SUPPLY 6 TIMING RES. 7 FEEDBACK 8 LOGIC OSC. & TIMING V DD HORN DRIVER V SS 16 GUARD 2 15 DETECT. IN 14 GUARD 1 13 SENSITIVITY SET 12 OSC. CAP. 11 HORN 2 10 HORN 1 9 – SUPPLY The A5348CA 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. Dwg. PC-004 The A5348CA 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 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 ■ ■ ■ ■ ■ ■ ■ ■ 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 Input Current, IIN ............................... 10 mA Operating Temperature Range, TA ..................................... 0 °C to +50°C Storage Temperature Range, TS ............................... -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. Always order by complete part number: A5348CA . 5348 SMOKE DETECTOR with INTERCONNECT and TIMER FUNCTIONAL BLOCK DIAGRAM AND TYPICAL APPLICATION + SUPPLY V I/O DD 6 9V 2 + FEEDBACK V DD 8 11 HORN – + 3 2 10 HORN 1 LOW-V SET LOGIC +V 5 LED 13 POWER-ON RESET – + SENSITIVITY SET TIMING RES. 7 OSCILLATOR & TIMING 12 – + – SUPPLY 4 9 TIMER OUT V SS 14 DETECT. 15 IN 16 GUARD 1 GUARD 2 +V OSC. CAP. 1 TIMER START +V Dwg. FC-001B 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 1990, 1995, Allegro MicroSystems, Inc. 5348 SMOKE DETECTOR with INTERCONNECT and TIMER ELECTRICAL CHARACTERISTICS at TA = +25°C, VDD = 9.0 V, VSS = 0 V, C12 = 0.1 µF, R7 = 8.2 MΩ (unless otherwise noted). Characteristic Limits Test 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, VIN = 0 to 9.0 V — — ±1.0 pA 14-15 Active Guard — — ±100 mV 16-15 Active Guard — — ±100 mV 15-13 Detect Comparator — — ±50 mV 13 No Alarm to Alarm 90 130 170 mV 14-15 Guard Amplifier 2.0 — VDD - 0.5 V 13-15 Smoke Comparator 0.5 — VDD - 2.0 V 14 to VSS — 10 — kΩ 16 to VSS — 500 — kΩ 12 No Alarm 1.34 1.67 2.00 s 32 40 48 ms 8.0 10 12 ms Input Offset Voltage Hysteresis Common Mode Range Active Guard Impedance Oscillator Period Alarm Oscillator Pulse Width 4 Timer Period 4 After Pin 1 High-to-Low, No Smoke 8.0 10 12 min Low Voltage Threshold 6 TA = 0 to 50°C 7.2 — 7.8 V Sensitivity Adj. Voltage 13 V13/V DD, pin 13 open circuit 48.5 50 51.5 % 10-11 IOUT = 16 mA, VDD = 9.0 V — 0.1 0.5 V IOUT = 16 mA, VDD = 7.2 V — — 0.9 V IOUT = -16 mA, V DD = 9.0 V 8.5 8.8 — V IOUT = -16 mA, V DD = 7.2 V 6.3 — — V Alarm 120 160 208 ms Low Battery 8.0 10 12 ms Alarm 60 80 104 ms Low Battery 32 40 48 s VIH 3.5 — — V VIL — — 1.5 V VIN = 9.0 V 20 — 80 µA Horn Output Voltage Horn Output ON Time Horn Output OFF Time Timer Start Logic Levels Timer Start Input Current 10-11 10-11 1 1 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 < V13; No Alarm (No Smoke) Condition as V15 > V13. 5348 SMOKE DETECTOR with INTERCONNECT and TIMER ELECTRICAL CHARACTERISTICS continued Characteristic Test Pin Limits Test Conditions Min. Typ. Max. Units Timer Out Output Current 4 VOUT = 0.5 V 500 — — µA LED Output ON Current 5 VDD = 7.2 V, VOUT = 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 No Alarm, Timer Mode After Pin 1 High-to-Low 8.0 10 12 s No Alarm, VI/O = VDD - 2.0 V 25 — 60 µA Alarm, VI/O = V DD - 2.0 V -7.5 — — mA I/O Current 2 I/O Alarm Voltage 2 External “Alarm” In 3.0 — — V I/O Delay 2 “Alarm” Out — 3.0 — s Supply Current 6 VDD = 9.0 V, No Alarm, No Loads — 5.0 9.0 µA VDD = 12 V, No Alarm, No Loads — — 12 µA 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 < V13; No Alarm (No Smoke) Condition as V15 > V13. CIRCUIT DESCRIPTION The A5348CA 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 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. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 5348 SMOKE DETECTOR with INTERCONNECT and TIMER 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 unit. TO OTHER UNITS 200 kΩ 200 kΩ TIMER MODE PUSH TO TEST 16 1 200 Ω 2 NOTE 3 15 LOGIC 3 14 4 5 6 8.2 MΩ 12 V DD 0.1 µF 11 HORN DRIVER 7 1 µF NOTE 1 13 OSC. & TIMING 330 Ω 10 8 V SS 9 200 kΩ 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. 9V 1 MΩ 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 Ω to 1000 Ω) such that the battery loading remains at 10 mA. TYPICAL APPLICATION 50 kΩ 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. 0.001 µF 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 V DD may be added to this pin to modify low battery voltage threshold. 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. 5348 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 10 ms 1.67 s 40 ms INTERNAL CLOCK 24 CLOCK CYCLES LED 30 CLOCK CYCLES 24 CLOCK CYCLES LED OFF LED ON 12 CLOCK CYCLES 6 CLOCK CYCLES 6 CLOCK CYCLES SMOKE COMPARATOR SAMPLE LOW BATTERY WARNING HORN ON HORN SMOKE CHAMBER OFF V15 < V13 (SMOKE) V15 > V13 (NO SMOKE) Dwg. WC-003 TIMER MODE V12 OSC. CAP 10 ms 1.67 s INTERNAL CLOCK 368 CLOCK CYCLES TIMER START TIMER OUT 6 CLOCK CYCLES OUTPUTS OFF (HIGH Z) LED LED ON END OF TIMER NOTIFICATION HORN Dwg. WC-005 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 5348 SMOKE DETECTOR with INTERCONNECT and TIMER I/O OPERATION REMOTE ALARM MODE 1.67 s 40 ms INTERNAL CLOCK 4 CYCLES HORN 2 CYCLES HORN ON OFF HORN NOT SELF COMPLETING WHEN IN REMOTE ONLY ALARM V2 IN I/O LOCAL ALARM MODE INTERNAL CLOCK HORN HORN ON OFF 72 CLOCK CYCLES V2 OUT I/O Dwg. WC-004 5348 SMOKE DETECTOR with INTERCONNECT and TIMER Dimensions in Inches (controlling dimensions) 0.014 0.008 9 16 0.430 MAX 0.280 0.240 0.300 BSC 1 0.070 0.045 0.100 0.775 0.735 8 0.005 BSC MIN 0.210 MAX 0.015 0.150 0.115 MIN 0.022 0.014 Dwg. MA-001-16A in Dimensions in Millimeters (for reference only) 0.355 0.204 9 16 10.92 MAX 7.11 6.10 7.62 BSC 1 1.77 1.15 2.54 19.68 18.67 BSC 8 0.13 MIN 5.33 MAX 0.39 3.81 2.93 MIN 0.558 0.356 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. Dwg. MA-001-16A mm 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