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MC145011P

Photoelectric Smoke Detector IC with I/O For Line-Powered Applications

Motorola => Freescale 

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

Photoelectric Smoke Detector IC

with I/O

For Line–Powered Applications

The CMOS MC145011 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

(photo–diodes). 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 load current from the LED pin. The trip point is set using two external

resistors. The supply for the MC145011 must be a dc power source capable of

supplying 35 mA continuously and 45 mA peak. When the MC145011 is in standby,

an external LED is continuously illuminated to indicate that the device is receiving

power.

An extinguished LED accompanied by a pulsating audible alarm indicates a

local–smoke condition. A pulsating audible alarm with the LED illuminated

indicates a remote–smoke condition. A beep or chirp indicates a low–supply

condition or degraded chamber sensitivity. A low–supply condition does not affect

the smoke detection capability if VDDw6 V. Therefore, the low–supply condition

and degraded chamber sensitivity can be distinguished by performing a

pushbutton (chamber) test. This 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 Standby Supply Current (Visible LED Illuminated): 20 mA

• 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

Order this document

by MC145011/D

MC145011

16

1

P SUFFIX

PLASTIC DIP

CASE 648–08

16

1

DW SUFFIX

PLASTIC SOIC

CASE 751G–03

ORDERING INFORMATION

MC145011P PLASTIC DIP

MC145011DW 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 3

©

Motorola Sensor

Motorola, Inc. 2001

Device

Data

1t

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