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TCA9548APWR

Ranjith Raviprakash
Prodigy 145 points
Other Parts Discussed in Thread: PCA9306, TCA9548A

We are using TCA9548APWR in one of our designs. We have connected VCC to 1.8V. SDA, SCL, Reset lines operate at 1.8V level. Can I connect the SC, SD signals to 3.3V pullup for some lines and 1.8V pullup few lines? is that acceptable?

  • 0
    TI__Genius 16510 points

    Hello Ranjith,

    While the switch does support voltage translation across it, one of the requirements is that the voltages on the switched side must be the same.  So you cannot mix and match voltages. However, if you do require translation, you may want to look at the pca9306 as it supports voltage translation from 1.8 to 3.3V.

  • 0 in reply to Jonathan Valdez
    Prodigy 145 points

    Hi Jonathan,

     Thanks for your reply.

    I’m not sure if that is what the datasheet says!  Take a look at the following section  on pages 10 and 19.  Even looking at the block diagram of the IC on page 11, I can’t see how they all have to have the same voltage.

    Page10 in datasheet

    The TCA9548A may also be used for voltage translation, allowing the use of different bus voltages on each
    SCn/SDn pair such that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts. This is achieved by using
    external pull-up resistors to pull the bus up to the desired voltage for the master and each slave channel.
    10

  • 0 in reply to Ranjith Raviprakash
    TI__Genius 16510 points
    Hello Ranjith,

    You are correct. The TCA9548A does allow for different voltage combinations to be used. The only requirement is that the VCC pin be at the LOWEST voltage used for a bus. So if you have the master at 3.3V, and slave channels at 5V, 2.5V, and 1.8V. You should have VCC at 1.8V to properly translate.

    My apologies for the mistake. I was going off of memory and was actually thinking about a different part.
  • 0 in reply to Jonathan Valdez
    Prodigy 145 points
    Thanks a lot Jonathan for quick response.