DA7838.002
20 September, 2000
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The MAS7838 requires clock signals in order to function
properly. The synchronous data transfer always
requires the TXC clock. The clock is used internally for:
-shifting data out from the TX buffer (to pin TDO)
-shifting data into the RX buffer (via pin RDI)
-detection of the bit rate in order to adjust the internal
baud rate generator (only if TSL = 1)
The asynchronous data transfer (pins TDI, TDO) is
accomplished by generating an internal timing signal for
the asychronous circuits. This internal timing signal
(16T) is 16 times the TXC bit rate in order to sample the
asynchronous data stream (TDI) at the proper speed.
Timing Circuits
16 x TXC
MAS 7838
TXC
EXTERNALLY GENERATED 16T CLOCK
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The MAS7838 is intended for applications where an
asynchronous and synchronous data source must be
linked together. A typical case appears in a data
modem
where the terminal interface of the modem has been
specified to be asynchronous but the modem data
pump operates in a synchronous fashion.
RS232C
MAS9138
MODEM CIRCUITS
INTERFACE
TXD
TDI
TDO
TXC
RDI
RXD
RDO
RXC
PHONE LINE
5 (9)
MAS [ MICRO ANALOG SYSTEMS ]
