SG1842/SG1843 Series

PRODUCT DA T ABOOK 1996/1997

Copyright © 2000

Rev. 1.6

4/00

12

TYPICAL APPLICA TION CIRCUITS

(continued)

FIGURE 20. — EXTERNAL DUTY CYCLE CLAMP AND

MULTI-UNIT SYNCHRONIZATION

FIGURE 19. — ADJUSTABLE BUFFERED REDUCTION OF CLAMP LEVEL

WITH SOFTSTART

Precision duty cycle limiting as well as synchronizing several 1842/

1843's is possible with the above circuitry.

Softstart and adjustable peak current can be done with the external

circuitry shown above.

t

1 -

C

where; V

minimum line and maximum load conditions.

I

Where: V

and V

7 (12)

6 (10)

7 (11)

5 (8)

3 (5)

SG1842/43

V

CC

V

IN

Q1

I

V

CS

R

S

5 (9)

8 (14)

4 (7)

2 (3)

1 (1)

MPSA63

R

2

R

1

C

2

6

R

B

R

A

1

84

3

555

TIMER

4 (7)

5 (9)

8 (14)

SG1842/43

To other

SGX842/43

















































FIGURE 22. — ERROR AMPLIFIER CONNECTION

FIGURE 21. — OSCILLATOR CONNECTION

8 (14)

4 (7)

5V

C

T

2.8V

1.1V

SG1842/43

Discharge

Current

I

R

T

1 (1)

R

F

R

i

2 (3)

R

2.5V

SG1842/43

0.5mA

The oscillator is programmed by the values selected for the timing

components R

Refer to application information for

calculation of the component values.

Error amplifier is capable of sourcing and sinking current up to 0.5mA.

R

R

V

5

R

1

R

R

1

R

f =

(R

1.44

f =

R

R

B

V

CS

R

S