MAS7838 ETC, MAS7838 Datasheet - Page 5

• Manufacturer Part Number: MAS7838
• Description: SYNCHRONOUS TO ASYNCHRONOUS CONVERTER SAC CMOS
• Manufacturer: ETC

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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)
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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
RS232C
EXTERNALLY GENERATED 16T CLOCK
INTERFACE
TXD
RXD
Timing Circuits
RDO
TDI
MAS9138
TDO
RXC
TXC
16 x TXC
RDI
TXC
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.
where the terminal interface of the modem has been
specified to be asynchronous but the modem data
pump operates in a synchronous fashion.
MODEM CIRCUITS
MAS 7838
PHONE LINE
20 September, 2000
DA7838.002
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