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TPS65084: I2C issue

Zhang Liang
Expert 2075 points
Part Number: TPS65084

Hi,

We use the TPS650842 for the Braswell CPU, now the I2C bus voltage is always high when power on, there are no I2C bus signal from PMIC;

We afraid the PMIC has any configuration to hand shake with the CPU, and we have little reference file from TI but only the datasheet;

Please kindy provide your comment, thanks.

N32 _ 17 CPU POWER TPS650842.pdf

  • 0
    TI__Expert 6700 points

    Hello Zhang,

    We have assigned this thread to the appropriate engineer who should be getting back to you sometime tomorrow.

    Regards,

    Alex

  • 0
    TI__Genius 15255 points

    Hi Zhang,

    Just to clarify, you are seeing the CLK and DATA lines of the PMIC go high during the power up cycle? If so, this is the expected behavior of the PMIC. When the I2C bus is idle, both DATA and CLK lines are pulled high. The master device (the Braswell CPU in this case) should be responsible for initiating the data transfer sequence by pulling the DATA pin low. Can you check to see if the CPU is transmitting a correct START condition on the DATA line when you try to read or write? If the CPU is not properly initiating I2C communication, the PMIC will not show a change in the I2C line voltages. If the CPU is not transmitting correctly I would check to make sure the input power VSYS and the BUCK regulators are outputting the expected stable voltages.

    There should not be any handshake type process involved in the I2C communication. The PMIC only requires the DATA line to go from High -> Low while the CLK pin is High to start data transfer.

    Regards,

    James