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TCA6416A: no response from this IO expander

Part Number: TCA6416A

Hi experts,

Please refer to below for my schematic with TCA6416ARTWR, I have 4 parts in this I2C bus, all the other three works well except this one.

1) VCCI and VCCP are powered with 3.3V directly, while I saw recommendation that VCCI comes up earlier than VCCP, will this be a problem?

2) I measured waveform, it seems this IO Expander won't response ACK.

3) For SCL and SDA are pulled-up to another 3.3V power rail, which rises up earlier than this 3.3V, is it OK?

4) Can I connect EPAD to GND? As I found this note in datasheet.

"The exposed center pad, if used, must be connected only as a secondary GND or must be left electrically open."

Thanks

Chris

  • Chris Zhao1 said:

    Part Number: TCA6416A

    Hi experts,

    Please refer to below for my schematic with TCA6416ARTWR, I have 4 parts in this I2C bus, all the other three works well except this one.

    1) VCCI and VCCP are powered with 3.3V directly, while I saw recommendation that VCCI comes up earlier than VCCP, will this be a problem?

    I would actually suggest VCCP go up before VCCI but it shouldn't matter if they both go up at relatively the same time (seeing as it looks like the two power rails are shared anyways)

    2) I measured waveform, it seems this IO Expander won't response ACK.

    You have your SDA from your master connected to SCL of our device and the SCL from the master to the SDA of our device. This is likely the cause.

    3) For SCL and SDA are pulled-up to another 3.3V power rail, which rises up earlier than this 3.3V, is it OK?

    Yes, this is fine.

    4) Can I connect EPAD to GND? As I found this note in datasheet.

    Yes.

    "The exposed center pad, if used, must be connected only as a secondary GND or must be left electrically open."

    Thanks

    Chris