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DA9138.005

12 April, 2006

APPLICATION INFORMATION

Data multiplexer

A third application is a data multiplexing/demultiplexing system. The system accepts data from several sources.

These data lines are sampled and the samples are sent through a multiplexer to a demultiplexer. To accomplish this,

either a very high sample rate is needed or first convert the data to synchronous mode, where synchronous

multiplexing can be used and only one sample per data bit is needed.

MAS9138

MAS9138

1

1

2

2

N

N

TDI

RDO

MAS9138

MAS9138

TDI

RDO

TDO

TDO

RDI

RDI

FORWARD

BACKWARD

MUX/

DEMUX

MUX/

DEMUX

TIMING

CH 1

CH 2

CH N

Synchronous modem with asynchronous interface

The following application shows how to add an asynchronous interface to a synchronous modem with MAS9138. TSL

and XHST inputs (pins 1 and 12) are connected to VDD. If the crystal is removed and the external 16 x TXC clock

signal is used (dotted line) then tie the TSL input to ground. CL1, Cl2, XASY and XHST are user adjustable with

jumpers or dip switches.

TTL/V28

78189A

TTL/V28

75189A

RS232C

TXD

RXD

Ext. Signal Rate

Char. Length

Char. Length

ASY/SYN Select

mode

selection

jumpers

TSL

XHST

+5v

-12v

+12v

*) Optional timing from the

synchronous modem.

In this case CR 1 can be

eliminated.

MAS9138 simplified application:

V.28 interface for synchronous modem

+5v

7

5

6

1

2

3

4

8

9

10

11

12

13

14

15

16

TDO

TTL-Level

TXC

TTL-Level

RDI

TTL-Level

RXC

TTL-Level

22pF

CR 1

9.8304MHz

22pF

Modem

Timing

Circuit

16 x TXC

*)

TXC

RXC

MAS9138

Synchronous

Modem

470pF

470pF

TDI

RDO