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UART Communication between 2.8V and 1.8V

ankur kumar4
Intellectual 310 points
Other Parts Discussed in Thread: PCA9306, TCA9406

I want to establish a UART communication between two modules. The Rx/Tx Voltage levels of the modules are 2.8V and 1.8V. Also, I have only 3.3V as the supply voltage on my board.

Kindly guide me as to how can I perform this level shifting.

 

Thanks

  • 0
    TI__Guru* 76221 points

    Hey Ankur,

    How fast are you planning on communicating on the Tx/Rx line (baud rate)?

    PCA9306 may be a good choice if you are below ~400kbps. You'll need to provide external pull up resistors on the side that is receiving the signal.

    TCA9406 will work for signals up to 24Mbps. No external pull up resistors needed for this one if the device is always enabled.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    Intellectual 310 points

    Hello 

    Thanks for your reply

    The constraint is that I have only 3.3V power supply available on my board. But I need a voltage level translation from 2.8 V to 1.8V (i.e. unidirectional voltage level shifter)

    Thanks

    Ankur

  • 0 in reply to ankur kumar4
    TI__Guru* 76221 points
    Hey Ankur,

    PCA9306 and TCA9406 should still work for your application if you are able to bias the VccA/VccB sides correctly. I know these are both bidirectional level shifters but that should not be a problem.

    If you absolutely cannot bias VccA/VccB using 2.8V and 1.8V and only have access to 3.3V then I can move your post to a different group (I provide I2C/UART support) who may have other options. Is this what you would prefer?

    Thanks,
    -Bobby