Design Documentation

Serial_A Module, MBARI 101225

4:36 PM 5/29/01 Dave Wright

General:

The Serial_A module provides 4 channels of transmit/receive RS-232 level conversion. Two identical modules share a common circuit board, and can be cut apart for space limited applications.

Circuit description:

U1 and U12 are Maxim MAX242 devices, common charge pump level converters. A jumper, OP1 and OP12 allows the shutdown control signal to be pulled up or down as needed by the application. Connectors J1, J2, J12 and J22 are for the RS-232 level signals. P1 and P12 are the power and logic level signals from the host controller.

Physical:

The module dimensions are 2.200" x 1.50". Mounting holes for #2 machine screws are provided at each corner. All thruhole connectors, and mounting holes, register with a 0.1" grid. This is to facillitate mounting of the module on standard perfboard for prototyping or "one off" construction. Active components are mounted on the "top" side, and serial I/O connectors on the "bottom" (non silkscreen) side. When mounted to a motherboard or other substrate, the component side faces "inward" to allow access to the connectors. Connector P1 contains the signals that are routed to the host microcontroller and power sources.


Assembly Notes:

The connectors for the RS-232 signals, J1, J2, J12 and J22 mount on the solder side of the board. All other components, including P1, mount on the component (silkscreen) side of the board.



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