Description

The A5366 is a low-current BiCMOS circuit providing all of

the required features for a photoelectric type smoke detector.

This device can be used with an infrared photoelectric chamber

to sense scattered light from smoke particles. A networking

capability allows as many as 50 units to be interconnected so that

if any unit senses smoke all units will sound an alarm. Special

features are incorporated in the design to facilitate calibration

and testing of the finished detector. The device is recognized by

Underwriters Laboratories for use in smoke alarms that comply

with Standard UL217, or UL268, per file #S2113.

A variable-gain photoamplifier can be directly interfaced to

an infrared emitter-detector pair. The amplifier gain levels are

determinedbytwoexternalcapacitorsandareinternallyselected

depending on the operating mode. Low gain is selected during

standby and timer modes. During a local alarm, this low gain

is increased (internally) by approximately 10% to reduce false

triggering. High gain is used during pushbutton test and to

periodically monitor the chamber sensitivity during standby.

The internal oscillator and timing circuitry keep standby power

to a minimum by sensing for smoke for only 100 μs every 10 s.

Aspecial three-stage–speedup sensing scheme is incorporated

to minimize the time to an audible alarm and also to reduce

false triggering. Chamber sensitivity is periodically monitored

and two consecutive cycles of degraded sensitivity are required

for a warning signal (chirp) to occur.

The A5366 is supplied in a 16-pin dual in-line plastic package

(suffix A), and for surface mount, a 16-pin SOICW (suffix

LW). The lead (Pb) free versions (suffix –T) have 100% matte-

tin leadframe plating. The devices are rated for continuous

operation over the temperature range of –25°C to 75°C.

26110.11-DS, Rev. G

Features and Benefits

▪ Low average standby current for long battery life

▪ Interconnect up to 50 detectors

▪ Piezoelectric horn driver

▪ Low battery detection (all internal)

▪ Chamber sensitivity test and alarm

▪ Power-on reset (POR)

▪ Internal timer and control for reduced sensitivity mode

▪ Built-in circuits to reduce false triggering

▪ 6 to 12 V operating range

▪ ESD protection circuitry on all pins

▪ Temporal Horn Pattern, per UL217, NFPA72, and ISO8201

▪ UL Recognized for UL217 or UL268 applications

Photoelectric Smoke Detector

with Interconnect and Timer

Packages:

Not to scale

A5366

16-pin DIP

(Package A)

16-pin SOICW

(Package LW)

Typical Application Diagram

C1

C2

DETECT

STROBE

VDD

IRED

HORN1

HORN2

I/O

FEEDBACK

LED

OSC CAP

TIMING RES

VSS

HUSH

TEST

A5366

To / from

other units

220 Ω

Rx2

Rx1

100 μF

1 kΩ

4.7 kΩ

5 kΩ

4700 pF

0.047 μF

560 Ω

200 kΩ

220 kΩ

1.5 MΩ

1000 pF

100 kΩ

10 MΩ

330 Ω

1500 pF

Red LED

Push-to-Test

9 V

22 μF

Connect HUSH to VSS

to disable timer mode

Value of component can vary,

based on the piezoelectric horn used

Connect to allow timer mode

("hush") operation

Piezo Horn

8.2 kΩ

22 Ω

Smoke

Chamber

B

C

C

C

C

B

A

A

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9