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Page 7 of 10

Issue A

LANSDALE Semiconductor, Inc.

ML145406

17

20 kΩ

NC

DO3

10 µF

RTLA**

DTMF

INPUT

RDSI

20 k

Ω

CDSI

6

9

1

15

8

3.579

MHz

3

11

5

14

2

13

7

12

4

19

10

18

16

VDD

TLA

DSI

Xin

Xout

CD

TxD

TxA

RxA2

RxA1

ExI

FB

VAG

CDT

GND

CDA

LB

SQT

RxD

RTx

600

+

10 kΩ

TIP

600:600

RING

VDD

VDD BYPASS

CFB

MODE

+ 5 V

1

ML145442/3

10 k

Ω

10 kΩ

CCDA**

0.1

µF

CCDT

VSS BYPASS

14

15

12

13

10

11

89

6

7

4

5

2

3

8

2

3

7

EIA 232–E

DB–25

CONNECTOR

NC

NC

VSS

GND

DI3

DO2

DI2

DO1

DI1

VDD

VCC

ML145406

Tx1

Rx1

Tx2

Rx2

Tx3

Rx3

16

– 5 V

*Line protection circuit

**Refer to the applications information for values of CCDA and RTLA

0.1 µF

0.1 µF

0.1 µF

0.1 µF

0.1

µF

10 k

10 kΩ

*

0.1 µF

0.1 µF

0.1 µF

Figure 5. 5–V 300–Baud Modem with EIA 232–E Interface