Document Number: MC14568

Rev. 1.0, 11/2006

Freescale Semiconductor

Product Preview

© Freescale Semiconductor, Inc., 2006. All rights reserved.

This document contains certain information on a new product.

Specifications and information herein are subject to change without notice.

Low-Power CMOS Ionization Smoke

Detector with Interconnect and Timer

The MC14568, 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.

An internal oscillator with associated logic controls 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 and

9.0

µA, thus providing longer battery life. In addition, a networking capability

allows as many as 125 to be interconnected so that if any unit senses smoke, all

units will sound an alarm.

The MC14568 is supplied in a 16-pin dual in-line plastic package and is

designed to run on a power supply between 6 to 12 Volts.

Features

•

Speed-Up Sampling Rate of 40 ms of Internal Clock Period (Pin 12) After First

Detection of Smoke

•

Timer Function for Reduced Sensitivity for a Nominal Period of 6.43 Minutes

(10 Minutes Max)

•

High-Smoke Detection in the “Reduced Sensitivity” Mode

•

Internal and External Low Battery Threshold

•

Internal and External Smoke Reference Settings

•

Guaranteed Power Up Without Random LED and Horn Chirps

•

Reversed Battery Protection

•

Low Leakage Detect Pin

•

Metal Option to Add Double Chirp at End of Reduced Sensitivity Period;

Default is No Chirp

•

Pb-Free Packaging Designated by Suffix Code ED

ORDERING INFORMATION

Device

Case No.

Package

PC14568P/R2

648-08

Plastic Dip

PC14568ED/R2

MC14568

P SUFFIX

ED SUFFIX (PB-FREE)

PLASTIC DIP

CASE 648-08

LOW-POWER CMOS IONIZATION

SMOKE DETECTOR WITH

INTERCONNECT AND TIMER

Figure 1. Pin Connections

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

TIMER START

I/O

LOW-V SET

TIMER OUT

LED

VDD

TIMING R

FEEDBACK

GUARD 2

DETECT INPUT

GUARD 1

SENSITIVITY SET

OSCILLATOR CAP

HORN 2

HORN 1

VSS