SP503AN

SP503 Application Note

© Copyright 2000 Sipex Corporation

7

SP503 Switching Configuration for V.35 Implementations

• Switches are Siliconix DG643DY analog switches.

• Solid-State Relays are AT&T, LH1514.

• Resistors are 1/8W, 1% tolerance.

Receivers

TxD

Drivers

DTR

RTS

14

13

16

15

TxC

SP503CF

RxD

RxC

CTS

DSR

DCD

1

20

80

78

19

RI

21

SCT

79

17

RL

24

LL

ST

22

V+

V-

+5V

Driver Outputs & Receiver Inputs

are in DTE mode.

to pin 12 of the 74LS11

to pin 12 of the 74LS11

to pin 12 of the 74LS11

74LS11

74LS11

74LS11 (3-Input AND Gate)

RxC (115)

A

B

RxD (104)

A

B

A

B

A

B

TxD (103)

A

B

TT (113)

TxCC (114)

A

B

to pin 6 of the 74LS11

74LS11

LH1514

74LS11

1

3

LH1514

7

5

1

LH1514

7

5

+12V

50

Ω

50

Ω

120

Ω

3

1

8

6

50

Ω

50

Ω

120

Ω

8

6

3

50

Ω

50

Ω

120

Ω

8

2

15

9

12

5

3

7

10 14

4

6

13

11

8

2

15

9

12

5

7

3

10

14

4

6

11

13

1

16

1

16

V+

V-

V+

200

Ω

200

Ω

232

Ω

232

Ω

-5V

107

Ω

V-

to V-

+12V

8

2

15

9

12

5

3

7

10 14

4

6

13

11

8

2

15

9

12

5

7

3

10

14

4

6

11

13

1

16

1

16

V+

V-

V+

+12V

200

Ω

200

Ω

232

Ω

232

Ω

-5V

107

Ω

V-

8

2

15

9

12

5

3

7

10 14

4

6

13

11

8

2

15

9

12

5

7

3

10

14

4

6

11

13

1

16

1

16

V+

V-

V+

+12V

+12V

200

Ω

200

Ω

232

Ω

232

Ω

-5V

107

Ω

+5V

16

1

13

212

1/4

74LS11

8

+5V

16

3

5

4

6

8

RDEC1 & TDEC1

RDEC2 & TDEC2

RDEC3 & TDEC3

(pins 3 & 11)

(pins 4 & 10)

(pins 5 & 9)

to pin 6 of the 74LS11

74LS11

8

6

7

5

1/4

74LS11