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SRC4392: I2C Issue, SDA tied to GND

Stian Blåsberg
Prodigy 30 points
Part Number: SRC4392

Hi all,

Im facing a issue with the SRC4392, it seems that once i connect the board that houses SRC4392 my I2C bus is broken. SDA/SCL is repectively pulled high by 3k3 resistors each one the board containing ESP32. There is an ADAU1467 on the same I2C bus which i can communicate with as long as the board with SRC4392 is disconnected. Doing a quick measurement i can see that the SDA is pulled down (20mV) which ofcourse will destroy the bus. Disconnecting the board and communications are fine again. Im attached my schematic, anyone who could see if ive made a mistake here? Ive been reading the datasheet but i cannot find anything wrong.. RST is pulled high so the device should be active.

Thanks,
Stian
digiboard_schem.pdf

  • 0
    Genius 3945 points

    Your schematic doesn't show "the other board."

  • 0 in reply to Andy Peters
    TI__Mastermind 18545 points

    Hello, 

    If you measure the resistance on the SRC4392 board (while powered down) between the SDA pin and GND, do you detect any shorts? Also, what happens if you just power up the SRC4392 board and try to communicate to only it through I2C? Do you have the same issue then? 

    Thank you, 

    Justin Beigel

  • 0 in reply to Justin Beigel
    Prodigy 30 points

    Hi Justin,

    Thank you for your reply.
    With multimeters black pin to GND: While powered down, there is no short between SDA and GND(Resistance measures to be from 30k - 150k), powering up again i have a resistance of about 33 ohm
    With multimeters red pin to GND: While powered down i measure 150 ohm between SDA and GND. While powered up i measure 0 ohm, short circuit.

    There is no difference if only this board is connected to ESP, iti s the same result

    EDIT: Ive also changed to another SRC4392 chip to make sure i dont have a failed one, same issue there.

  • 0
    Prodigy 30 points

    So turns out it was another dummy mistake, i thought there was an internal regulator for the VDD18 for some reasons i do not know.. Turns out it is not, so once the core got its 1.8v the device works fine :-D