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PCA9306: PCA9306 does it work for UART applications

Sunset
Genius 14075 points
Part Number: PCA9306
Other Parts Discussed in Thread: TXS0102

Hello Team,

does it work the PCA9306 for UART applications?

In this case the pull up resistors on SDA/SCL would not be present.

For UART would be TX and RX channel.

From the datasheet I do not see anything preventing it.

Can I use only one channel and use the second one floating?

I'm also considering the TXS0102 since it integrates the pull up resistors and does not need the external resistor for Vref.

The reason behind the question is due to the fact that connecting the systems on the PCA9306, we do see that the 0V pulled from one system (1.8V side) does not go low on the 3.3V side. We are able to pull it down till 0.3V which sounds like an ESD diode ON. Thus the question on the must to have the pull up resistor.

We are still investigating on the current that really flows, and if the 1.8V system is really capable of pulling low the line.

Thanks for the follow up.

SunSet

  • 0
    TI__Mastermind 26826 points

    SunSet,

    If you are unable to put pull-up resistors in, then I would not recommend the PCA9306 for this. If you want to use the PCA9306 for UART, you would need pull-up resistors  Without pull-up resistors, it is possible that the signal will not fully get back up to Vcc.

    The TXS0102 would likely be better because it includes rise time accelerators to temporarily supply a fast rising edge and has internal pull-ups, as you noted.

    Please let me know if there are any further developments you need help with!

    Best,

    Danny

    ---------------

    Also, here is another similar E2E post that may provide some more helpful info:

  • 0 in reply to Danny Bacic
    TI__Genius 14075 points

    Thanks for the feedback.

    Yes, probably the TXS0102 would remain the optimal solution since it integrates the pull up resistors.

    Ciao,

    SunSet