A5366CA : Photoelectric Smoke Detector with Interconnect and timer

Manufacturer: Allegro Micro

Report by Younji Choi Mar 29, 2007

DATASHEET

http://itp.nyu.edu/~yjc272/sensorWorkshop/5366.pdf

DESCRIPTION

The MC14468, when used with an ionization chamber and a small number of external components, will detect smoke. When smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications.

Features

    * Ionization Type with On–Chip FET Input Comparator
    * Piezoelectric Horn Driver
    * Guard Outputs on Both Sides of Detect Input
    * Input–Production Diodes on the Detect Input
    * Low–Battery Trip Point, Internally Set, can be Altered Via External Resistor
    * Detect Threshold, Internally Set, can be Altered Via External Resistor
    * Pulse Testing for Low Battery Uses LED for Battery Loading
    * Comparator Output for Detect
    * Internal Reverse Battery Protection
    * Strobe Output for External Trim Resistors
    * I/O Pin Allows Up to 40 Units to be Connected for Common Signaling
    * Power–On Reset Prevents False Alarms on Battery Change

AVAILABILITY AND PRICINGS

You may want to go to Freescale directly, and order some free sample.

pricings by manufacturer: Budgetary Price QTY 1000+ ($US) :$0.53

THEORY OF OPERATION

An internal oscillator with associated logic control the overall functionality by powering down the device for 1.67 seconds and sensing smoke in a 10 ms window. in this way, standby current consumption is reduced to between 5.0, thus providing longer battery life. In addition, a networking capacity allows as many as 125 to be interconnected so that if any unit senses smoke, all unites will sound an alarm. (from datasheet)

ELECTRICAL CHARACARISTICS

Datasheet explains fairly straight forward.

The MC14468 operates on 6.0 - 12.0VDC, and uses very little current (10mA). It has three analog outputs, one for each axis. Acceleration on each axis generates a voltage from 0 to approximately 3.3V.

When there's no acceleration on a given axis, the output for that axis outputs half the supply voltage, or about 1.65V. With acceleration in a positive direction along the axis, the output voltage for that axis rises. With negative acceleration along the axis, the voltage goes down. In other words:

    * at rest the voltage is in the middle;
    * at full forward acceleration, the voltage is at its highest;
    * at full backward acceleration, the voltage is at its lowest.