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PCA9306: PCA9306 for RS232 with 115200bps

Jack CCY
Intellectual 1695 points
Part Number: PCA9306
Other Parts Discussed in Thread: TRS3122E

Hi team,

Can PCA9306 be used for RS232 UART TX RX 115200 bps level translation? 1.8V to 3.3V?

Thanks.

  • 0
    TI__Guru 62920 points

    Jack,

    Yes, this device could be used to translate UART communication between those two voltage levels.  Just be sure to follow the recommended connections in the datasheet (including pull-up resistors on the SDA/SCL IOs on both sides, which may not be required by the UART but would be required by PCA9306).

    If you actually needed RS-232 voltage levels (i.e., to interface to an external RS-232 port), you could connect the 1.8-V or 3.3-V logic lines to an RS-232 transceiver.  Please let us know if you need help selecting a transceiver device.  For example, TRS3122E might be something to consider since it is able to interface to either 3.3-V or 1.8-V UART signals.

    Regards,
    Max

  • 0
    TI__Guru 53575 points

    Hi Jack,

    I can see how PCA9306 could be suited for this application. There doesn't seem to be any glaring problems, but in any use-case apart from intended, I would advice some careful considerations:

    • Pull-up resistors will need to be included on the RS-232-side TX line and the UART-side RX line to allow the lines to go high when the switch disconnects. 
    • Select pull-up values to properly drive RS-232 and UART input pin current and evaluate that resulting RC time constant is acceptable. 
    • Ensure feedback delay introduced by translation (both ways) is acceptable to UART RS-232 driver. 
    • Be sure that the current passed through the device does not exceed the Pass Switch Current (Recommended Max) or Continuous Channel Current (Absolute Max).

    I will keep you notified if I become aware of other important considerations. Let me know if you have any other questions.

    Regards,

    Eric