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TCA9554A: Inquiry

Ray Vincent Aranzaso
Genius 14685 points
Part Number: TCA9554A

Hi,

Good Day. I have a customer who is working with TCA9554ADBR. Please see below his query for your reference. Thank you very much.

If I power it on with 2.5V (connect VCC to 2.5V) but my I2C bus voltage is 5V, is that operationally ok?

I looked thru the datasheet and it doesn't seem like it's an issue but I would like to double check.

Best Regards,

Ray Vincent

  • 0
    Guru 262920 points

    You will get a leakage current (see footnote (1) in section 6.3 of the datasheet).

  • 0 in reply to Clemens Ladisch
    TI__Genius 15345 points

    Ray,

    As Clemens said you will not only see a greater leakage current but you could potentially back bias the devices on your voltage rail. They could see a reverse bias on their supply pins.

    Even if back biasing wasn't an issue keep in mind that your thresholds on the I2C bus are based on the VCC pin of the device. In a case where the I2C Bus > VCC this threshold issue shouldn't be a problem. But in the case where the I2C bus < VCC this becomes a problem. In general it is a good idea to have both the VCC pins and the I2C rail have the same voltage.

    Best,

    Chris