Isolated Transformer Driver

for PCMCIA Applications

______________________________________________________________________________________

11

C3

0.1µF

C2

2.2µF

ISO 5V

ISOLATION

BARRIER

5V

1

8

5

C1

0.1µF

MBR0520

MAX845

D1

D2

GND1 GND2

6

2

7

N.C.

SD

4

ON / OFF

10 x PC417

*74HC04 OR EQUIVALENT

MAX225

EN

SD

C4

2.2µF

8

2

MBR0520

MAX883

5

6

4

SHDN

SET

GND

IN

OUT

390

Ω

3

11

13, 14

27, 28

390

Ω

*74HC04

1

2

4

5

6

1

2

4

5

6

390

Ω

74HC04

390

Ω

74HC04

390

Ω

74HC04

390

Ω

74HC04

74HC04

74HC04

74HC04

74HC04

74HC04

5 x 3.3k

390

Ω

390

Ω

390

Ω

390

Ω

4

12

25

18

24

17

23

16

5

10

6

9

7

8

22

19

21

20

2

1

GND

5 x 3.3k

1N5711

6

5

4

1

2

390

Ω

3.3k

ISO

1CT:1.3CT

1N5711

1

2

6

5

4

390

Ω

3.3k

ISO

*74HC04

4N25 LOWER SPEED, LOWER COST ALTERNATE OPTOCOUPLER CONFIGURATIONS (FOR DATA RATES BELOW 9.6kbps)

FS

3

74HCO4

4N25

ISO

GND

4N25

ISO

GND

N.C.

Figure 10. Typical RS-232 Application Circuit