SYNC_TO_ASYNC_CONVERTER

Published:2009/6/22 23:58:00 Author:May | From:SeekIC

This simple converter donsists of two ICs and a voltage regulator. The Sipex MAS7838, which acts as the converter, selects the conversion speed to that of the synchronized data clock. It has intemal switches and registers to perform the async-to-sync, or sync-to-async, conversion. The Maxim MAX238 provides the RS-232 drivers and receivers for interfacing with the data bus. These chips require a 5-Vdc power supply; a generic 78L05 reduces the +12V at the DB25 pin 9 to the +5V needed. A crystal fre-quency of 4.91MHz is suitable for convetting to 19.2 kbits or a sub-multiple (9.6, 4.8, 2.4, etc.). Two 1N4001 diodes protect the extemal RTS (ready to send) control circuitry if the RTS is enabled by S1.When JP1 is removed, the converter is transparent in the sync mocte and no conversion will occur.The completed unit is mounted atop a universal breakout adapter, and the control lines are jumpered according to the chart in the figure. The physical size is approximately 1 x 2.25 x 2.5 inches and will easily plug into the DB25 socket on a synchronized data communications equipment (DCE) communication device.



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