RE46C145

DS22181C-page 2

 2009-2012 Microchip Technology Inc.

Functional Block Diagram

Typical Application

Logic and

Timing

Bias and

Power Reset

Oscillator

+

-

+

-

VDD (5)

VSEN (15)

C1 (1)

DETECT (3)

C2 (2)

TEST (16)

IO (7)

FEED (10)

HS (9)

LED (11)

IRED (6)

ROSC (13)

COSC (12)

HB (8)

+

-

PHOTOAMP

STROBE (4)

VSS (14)

Low Battery

Smoke Comparator

Horn Driver

Push-to-Test

C3

1μF

C5

1.5nF

R12

10M

R9

100k

R13

330

D3

C6

1.0nF

R10

1.5M

R11

220k

R8

100

R7

22

C4

100 μF

D5

D6

R4

560

C2

4700 pF

C1

.047 μF

R1

4.7k

R2

5k

R3

8.2k

R6

1k

1

2

3

4

5

14

6

7

89

10

11

12

13

15

16

R5

250k

To Other Units

Q3

9V

Battery

Smoke Chamber

Note 1:

C3 should be located as close as possible to the device power pins.

2:

C3 is typical for an alkaline battery. This capacitance should be increased to 4.7 µF or greater for a carbon battery.

3:

R10, R11 and C6 are typical values and may be adjusted to maximize sound pressure.