MAS9138 MAS, MAS9138 Datasheet - Page 8

• Manufacturer Part Number: MAS9138
• Description: ASYNCHRONOUS TO SYNCHRONOUS CONVERTER
• Manufacturer: MAS

APPLICATION INFORMATION
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.
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.
TXD
RXD
Data multiplexer
Synchronous modem with asynchronous interface
CH N
CH 1
CH 2
RS232C
RDO
TDI
selection
jumpers
mode
470pF
470pF
M AS9138
M AS9138
1
2
N
-12v
TTL/V28
78189A
TTL/V28
75189A
+12v
TDO
RDI
ASY/SYN Select
Ext. Signal Rate
Char. Length
Char. Length
+5v
RDO
TDI
XHST
TSL
DEMUX
MUX/
*) Optional timing from the
synchronous modem.
In this case CR 1 can be
eliminated.
MAS9138 simplified application:
V.28 interface for synchronous modem
9
13
1
12
7
5
6
11
MAS9138
FORWARD
BACKWARD
+5v
TIMING
16
8
14
15
10
4
2
3
CR 1
DEMUX
MUX/
TDO
RXC
TXC
RDI
TTL-Level
TTL-Level
TTL-Level
TTL-Level
22pF
9.8304MHz
22pF
*)
RDI
TDO
16 x TXC
M AS9138
M AS9138
Modem
Timing
Circuit
Synchronous
Modem
2
1
N
12 April, 2006
RXC
DA9138.005
TXC
8 (10)
RDO
TDI