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MC145012

Photoelectic Smoke Detector IC with I/O and Temporal Pattern Horn Driver

Motorola => Freescale 

MOTOROLA

SEMICONDUCTOR

TECFHrNeICeAsLcDaAleTASemiconductor,

Inc.

Order this document

by MC145012/D

Photoelectric Smoke

Detector IC with I/O and

Temporal Pattern Horn Driver

The CMOS MC145012 is an advanced smoke detector component

containing sophisticated very--low--power analog and digital circuitry. The IC is

used with an infrared photoelectric chamber. Detection is accomplished by

sensing scattered light from minute smoke particles or other aerosols. When

detection occurs, a pulsating alarm is sounded via on--chip push--pull drivers

and an external piezoelectric transducer.

The variable--gain photo amplifier allows direct interface to IR detectors

(photodiodes). Two external capacitors, C1 and C2, C1 being the larger,

determine the gain settings. Low gain is selected by the IC during most of the

standby state. Medium gain is selected during a local--smoke condition. High

gain is used during pushbutton test. During standby, the special monitor circuit

which periodically checks for degraded chamber sensitivity uses high gain also.

The I/O pin, in combination with VSS, can be used to interconnect up to 40

units for common signaling. An on--chip current sink provides noise immunity

when the I/O is an input. A local--smoke condition activates the short--circuit--

protected I/O driver, thereby signaling remote smoke to the interconnected

units. Additionally, the I/O pin can be used to activate escape lights, enable

auxiliary or remote alarms, and/or initiate auto--dialers.

While in standby, the low--supply detection circuitry conducts periodic checks

using a pulsed load current from the LED pin. The trip point is set using two

external resistors. The supply for the MC145012 can be a 9 V battery.

A visible LED flash accompanying a pulsating audible alarm indicates a

local--smoke condition. A pulsating audible alarm with no LED flash indicates a

remote--smoke condition. A beep or chirp occurring virtually simultaneously

with an LED flash indicates a low--supply condition. A beep or chirp occurring

halfway between LED flashes indicates degraded chamber sensitivity. A

low--supply condition does not affect the smoke detection capability if VDD ≥ 6 V.

Therefore, the low--supply condition and degraded chamber sensitivity can be

further distinguished by performing a pushbutton (chamber) test.

• Circuit is designed to operate in smoke detector systems that comply with

UL217 and UL268 Specifications

• Operating Voltage Range: 6 to 12 V

• Operating Temperature Range: -- 10 to 60°C

• Average Supply Current: 8 µA

• I/O Pin Allows Units to be Interconnected for Common Signalling

• Power--On Reset Places IC in Standby Mode (Non--Alarm State)

• Electrostatic Discharge (ESD) and Latch Up Protection Circuitry on All Pins

• Chip Complexity: 2000 FETs, 12 NPNs, 16 Resistors, and 10 Capacitors

• Supports NFPA 72, ANSI S3.41, and ISO 8201 Audible Emergency

Evacuation Signals

• Ideal for battery--powered applications

MC145012

16

1

P SUFFIX

PLASTIC DIP

CASE 648--08

16

1

DW SUFFIX

SOIC PACKAGE

CASE 751G--03

ORDERING INFORMATION

MC145012P PLASTIC DIP

MC145012DW SOIC PACKAGE

PIN ASSIGNMENT

C1 1

C2 2

Detect 3

Strobe 4

VDD 5

IRED 6

I/O 7

Brass 8

16 Test

15

Low--Supply

Trip

14 VSS

13 R1

12 Osc

11 LED

10 Feedback

9 Silver

REV 5

© MMotootroolrao, Ilnac.S2e00n1sor Device Data For More Information On This Product,

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