A5349CA-T [ALLEGRO]

Analog Circuit, 1 Func, CMOS, PDIP16, LEAD FREE, PLASTIC, MS-001BB, DIP-16;


型号：	A5349CA-T
厂家：	ALLEGRO MICROSYSTEMS
描述：	Analog Circuit, 1 Func, CMOS, PDIP16, LEAD FREE, PLASTIC, MS-001BB, DIP-16
文件：	总8页 (文件大小：85K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

5349

AC SMOKE DETECTOR

WITH INTERCONNECT AND TIMER

The A5349CA is a low-current, CMOS circuit providing all of the

required features for an ionization-type smoke detector. A networking

capability allows as many as 125 units to be interconnected so that if

any unit senses smoke, all units will sound an alarm. In addition,

special features are incorporated to facilitate alignment and test of the

finished smoke detector. This device is designed to comply with

Underwriters Laboratories Specification UL217.

TIMER START

I / O

GUARD

DETECT. IN

LOGIC

LOW-V SET

TIMER OUT

LED

GUARD

SENSITIVITY

SET

The internal oscillator and timing circuitry keeps standby power to

a minimum by powering down the device for 1.66 seconds and sensing

smoke for only 10 ms. Every 24 on/off cycles, a check is made for low

battery condition. By substituting other types of sensors, or a switch for

the ionization detector, this very-low power device can be used in

numerous other safety or security applications.

OSC. &

TIMING

OSC. CAP.

+ SUPPLY

HORN

DRIVER

TIMING RES.

FEEDBACK

HORN

– SUPPLY

The A5349CA is supplied in a low-cost, 16-pin dual in-line plastic

package. It is rated for continuous operation over the temperature

range of 0°C to +50°C.

Dwg. PC-004

FEATURES

■ Interconnect Up to 125 Detectors

■ Piezoelectric Horn Driver

■ Guard Outputs for Detector Input

■ Low Supply Detection

■ Power-ON Reset

■ Internal Timer & Control for Reduced Sensitivity

■ Built-In Hysteresis Reduces False Triggering

ABSOLUTE MAXIMUM RATINGS

(Voltages are referenced to V_SS

)

Supply Voltage Range,

_DD................................ -0.5 V to +15 V

Input Voltage Range,

_IN........................ -0.3 V to V_DD+ 0.3 V

Input Current, I_IN................................ 10 mA

Operating Temperature Range,

T_A..................................... 0°C to +50°C

Storage Temperature Range,

T_S................................ -55°C to +125°C

CAUTION: CMOS devices have input static

protection but are susceptible to damage when

exposed to extremely high static electrical

charges.

Always order by complete part number: A5349CA .

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

FUNCTIONAL BLOCK DIAGRAM AND TYPICAL APPLICATION

+ SUPPLY V

I / O

FEEDBACK

HORN

–

HORN

LOW-V

SET

LOGIC

LED

–

POWER-ON

RESET

SENSITIVITY

SET

TIMING RES.

OSC. CAP.

OSCILLATOR

& TIMING

–

– SUPPLY

TIMER OUT

DETECT.

TIMER

START

GUARD

Dwg. FC-005A

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

ELECTRICAL CHARACTERISTICS at T_A= +25°C, V_DD= 9.0 V, V_SS= 0 V, C₁₂= 0.1 µF,

R₇= 8.2 MΩ (unless otherwise noted).

Limits

Test

Characteristic

Test Conditions

Operating

Min.

6.0

—

Typ.

9.0

—

Max.

Units

Supply Voltage Range

Detector Input Current

Input Offset Voltage

0 to 40% RH, V_IN= 0 to 9.0 V

Active Guard

Detect Comparator

No Alarm to Alarm

Guard Amplifier

Smoke Comparator

to V_SS

±1.0

±100

±50

170

V_DD- 0.5

V_DD- 2.0

—

14-15

16-15

15-13

—

Hysteresis

130

—

Common Mode Range

14-15

13-15

2.0

0.5

—

Active Guard Impedance

Oscillator Period

500

1.67

—

kΩ

to V_SS

—

No Alarm

1.34

2.00

Alarm

min

Oscillator Pulse Width

Timer Period

8.0

7.2

48.5

—

After Pin 1 High-to-Low, No Smoke

T_A= 0 to 50°C

Low Voltage Threshold

Sensitivity Adj. Voltage

Horn Output Voltage

7.8

V₁₃/ V_DD, pin 13 open circuit

I_OUT= 16 mA, V_DD= 9.0 V

I_OUT= 16 mA, V_DD= 7.2 V

I_OUT= -16 mA, V_DD= 9.0 V

I_OUT= -16 mA, V_DD= 7.2 V

Alarm

0.1

—

51.5

0.5

10-11

—

0.9

8.5

6.3

120

8.0

8.8

—

Horn Output ON Time

Horn Output OFF Time

Timer Start Logic Levels

10-11

160

—

208

Low Battery

Alarm

104

Low Battery

V_IH

3.5

—

V_IL

—

1.5

Timer Start Input Current

Timer Out Output Current

V_IN= 9.0 V

—

µA

V_OUT= 0.5 V

500

—

Continued next page . . .

NOTE 1: Negative current is defined as coming out of (sourcing) the specified device pin.

NOTE 2: Alarm (Smoke) Condition is defined as V₁₅< V₁₃; No Alarm (No Smoke) Condition as V₁₅> V₁₃

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

ELECTRICAL CHARACTERISTICS continued

Limits

Test

Characteristic

Test Conditions

V_DD= 7.2 V, V_OUT= 1.0 V

Local Alarm

Min.

Typ.

Max.

Units

—

LED Output ON Current

LED Output ON Time

—

constant OFF

8.35

Timer Mode, No Alarm

No Alarm, In Standby

—

LED Output OFF Time

I/O Current

constant ON

—

No Alarm, Timer Mode After Pin 1

High-to-Low

—

1.67

—

µA

No Alarm, V_I/O= V_DD– 2.0 V

Alarm, V_I/O= V_DD– 2.0 V

External “Alarm” In

-7.5

3.0

—

I/O Alarm Voltage

I/O Delay

—

“Alarm” Out

3.0

5.0

—

Supply Current

V_DD= 9.0 V, No Alarm, No Loads

V_DD= 12 V, No Alarm, No Loads

—

9.0

µA

—

NOTE 1: Negative current is defined as coming out of (sourcing) the specified device pin.

NOTE 2: Alarm (Smoke) Condition is defined as V₁₅< V₁₃; No Alarm (No Smoke) Condition as V₁₅> V₁₃

CIRCUIT DESCRIPTION

The A5349CA is a low-current CMOS circuit providing all of the

required features for an ionization-type smoke detector.

Oscillator. An internal oscillator operates with a period of 1.67

seconds during no-smoke conditions. Every 1.67 seconds, internal

power is applied to the entire circuit and a check is made for smoke.

Every 24 clock cycles (40 seconds), a check is made for low supply by

comparing V_DDto an internal reference. Since very-low currents are

used in the device, the oscillator capacitor at pin 12 should be a low-

leakage type (PTFE, polystyrene, or polypropylene).

Detector Circuitry. When smoke is detected, the resistor divider

network that sets the sensitivity (smoke trip point) is altered to in-

crease the sensitivity set voltage (pin 13) by typically 130 mV with no

external connections to pins 3 or 13. This provides hysteresis and

reduces false triggering. An active guard is provided on both pins

adjacent to the detector input (pin 15). The voltage at pins 14 and 16

will be within 100 mV of the input. This will keep surface leakage

currents to a minimum and provide a method of measuring the input

voltage without loading the ionization chamber. The active-guard

amplifier is not power strobed and thus provides constant protection

from surface leakage currents. The detector input has internal diode

protection against static damage.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

Alarm Circuitry. If smoke is detected, the

oscillator period changes to 40 ms and the

horn is enabled. The horn output is typically

160 ms ON, 80 ms OFF. During the OFF

time, smoke is again checked and will inhibit

further alarm output if smoke is not sensed.

During smoke conditions the low-supply

alarm is inhibited.

TYPICAL APPLICATION

200 kΩ

+ SUPPLY

TIMER

MODE

PUSH

TEST

OTHER

UNITS

LED. The LED is continuously ON during the

standby mode indicating the unit is receiving

power. During a remote alarm condition the

LED remains ON. The LED is OFF during a

local alarm condition.

200 Ω

LOGIC

NOTE

OSC. &

TIMING

330 Ω

Sensitivity Adjust. The detector sensitivity

to smoke is set internally by a voltage divider

connected between V_DDand V_SS. The

sensitivity can be externally adjusted to the

individual characteristics of the ionization

chamber by connecting a resistor between

pin 13 and V_DD, or between pin 13 and V_SS.

0.1 µF

HORN

DRIVER

8.2 MΩ

1 µF

0.001 µF

Low Supply. The low supply threshold is set

internally by a voltage divider connected

between V_DDand V_SS. The threshold can be

increased by connecting a resistor between

pin 3 and V_DD. The threshold can be de-

creased by connecting a resistor between pin

3 and V_SS. The supply voltage level is

checked every 40 seconds.

NOTE 2

Dwg. EC-005-1A

NOTE 1: Use an external resistor to adjust sensitivity for a particular

smoke chamber.

NOTE 2: Select resistor to reduce sensitivity during timer mode.

NOTE 3: A resistor to ground or V_DDmay be added to this pin to modify low battery

voltage threshold.

NOTE 4: Reverse supply protection must be supplied externally.

Timer. An internal timer is provided that can

be used in various configurations to allow for

a period of reduced smoke detector sensitiv-

ity (“hush”). When a high-to-low transition

occurs at pin 1, the internal timer is reset, the

timer mode enabled, and the circuit reset to a

no-alarm condition (the LED will flash at a 10

second rate). If the level of smoke is in-

creased such that the reduced sensitivity

level is reached, the device will go into the

alarm condition. The timer, however, will

continue to completion of the nominal 10-1/4

minute period (368 clock cycles). If the timer

mode is not used, pin 1 should be tied low.

sound their associated horns after a nominal 3 second delay. The LED

remains ON when an alarm is signaled from an interconnected unit

and a local smoke condition does not exist.

Testing. On power up, all internal counters are reset. Internal test

circuitry allows for low-battery check by holding pins 8 and 12 low

during power up, then reducing V_DDand monitoring HORN₁(pin 10).

All functional tests can be accelerated by driving pin 12 with a 2 kHz

square wave. The 10 ms strobe period must be maintained for proper

operation of the comparator circuitry.

I/O. A connection is provided at pin 2 to

allow multiple smoke detectors to be

commoned. If any single unit detects smoke

(I/O is driven high), all connected units will

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

TIMING DIAGRAMS IN TYPICAL APPLICATION

NON-TIMER MODE

NO ALARM

NO LOW BATTERY

STANDBY MODE

ALARM

NO LOW BATTERY

ALARM AND

LOW BATTERY

NO ALARM

LOW BATTERY

V12

OSC. CAP

10 ms

1.67 s

40 ms

INTERNAL

CLOCK

30 CLOCK CYCLES

24 CLOCK CYCLES

LED ON

24 CLOCK CYCLES

LED OFF

LED

12 CLOCK CYCLES

6 CLOCK

CYCLES

6 CLOCK

CYCLES

SMOKE

COMPARATOR

SAMPLE

LOW BATTERY

WARNING

HORN

OFF

Dwg. WC-006

V15 < V13 (SMOKE)

SMOKE

CHAMBER

V15 > V13 (NO SMOKE)

TIMER MODE

V12

OSC. CAP

10 ms

1.67 s

INTERNAL

CLOCK

368 CLOCK CYCLES

TIMER

START

TIMER

OUT

OUTPUTS OFF

6 CLOCK CYCLES

LED

OFF

END OF TIMER

NOTIFICATION

HORN

Dwg. WC-007

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

I/O OPERATION

REMOTE ALARM MODE

1.67 s

40 ms

INTERNAL

CLOCK

4 CYCLES

2 CYCLES

HORN

OFF

HORN

HORN NOT SELF COMPLETING

WHEN IN REMOTE ONLY ALARM

V2 IN

I/O

LOCAL ALARM MODE

INTERNAL

CLOCK

HORN

OFF

HORN

72 CLOCK CYCLES

V2 OUT

I/O

Dwg. WC-004

5349

AC SMOKE DETECTOR

with INTERCONNECT

and TIMER

Dimensions in Inches

(controlling dimensions)

0.014

0.008

0.430

MAX

0.280

0.240

0.300

BSC

0.100

0.070

0.045

0.005

BSC

MIN

0.775

0.735

0.210

MAX

0.015

0.150

0.115

MIN

0.022

0.014

Dwg. MA-001-16A in

Dimensions in Millimeters

(for reference only)

0.355

0.204

10.92

MAX

7.11

6.10

7.62

BSC

1.77

1.15

2.54

0.13

BSC

MIN

19.68

18.67

5.33

MAX

0.39

3.81

2.93

MIN

0.558

0.356

Dwg. MA-001-16A mm

Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from

the detail specifications as may be required to permit improvements in the design of its products.

The information included herein is believed to be accurate and reliable. However, Allegro

MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements of patents or

other rights of third parties which may result from its use.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

A5349CA-T [ALLEGRO]

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