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SN75DP130: DP Port Redriver SN75DP130SS I2C access issue !!!

Sunil S Bhonsle
Prodigy 70 points
Part Number: SN75DP130

Hi,

We are using SN75DP130SS in our project and it's I2C is driven by ZynQ SOC processor. We are finding issue that I2C is not responding and we are not getting Ack bit from I2C commands.

We can share the Schematic and Test code if required. Kindly advice.

Thank you,
Sunil

  • 0
    TI__Mastermind 23815 points
    Hi Sunil,

    The device is working fine but you are unable to have I2C communication, right?
    Can you share scope captures of the NAK transaction?
    Please share the schematic part of the ADDR pin

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 70 points

    Hi Moises,

    Yes, you are right. Please find the scope captures and complete schematic.

    Thanks in advance.

  • 0 in reply to Sunil S Bhonsle
    TI__Mastermind 23815 points
    Hi Sunil,

    Thanks for the data, I have saved and removed the schematic from the previous post.
    In the schematic you have pull-up and pull-down populated, this will make ADDR_EQ = Vcc/2, the I2C address will be 0x2D.
    In the scope capture, you are using I2C address 0x2E, to have this address you need to populate the pull-up and remove the pull-down on ADDR_EQ pin.
    Changing the I2C address will change the EQ behavior too.

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 70 points

    Hi Moises,

    Thanks for your immediate response. 

    R545 and R546 are not mounted, hence ADDR_EQ and EN-EQ are pulled high.

  • 0 in reply to Sunil S Bhonsle
    TI__Mastermind 23815 points
    Hi Sunil,

    This is weird, I just tested the three I2C address in the EVM, all of them work fine.
    Have you tried the three address?
    Could you measure the voltage in DP130's ADD_EQ pin? this is to make sure the right address is selected.
    Have you tried a different I2C?
    Could you confirm the PCB has a solid pad from DP130's I2C pins to master pins?

    Regards
  • 0 in reply to Moises Garcia
    Prodigy 70 points

    Hi Moises,

    Please find my reply as below

    1. Have you tried the three I2C address?

    Yes, we have tried all three addresses. now we have pull high through 4.64K.

     2. Could you measure the voltage in DP130's ADD_EQ pin? this is to make sure the right address is selected.

    Yes, it is 3.3V.

     3. Have you tried a different I2C?

    Can you please elaborate on this?

     4. Could you confirm the PCB has a solid pad from DP130's I2C pins to master pins?
      Attached Board top layer snap, focusing device footprint.

  • 0 in reply to Sunil S Bhonsle
    TI__Mastermind 23815 points
    Hi Sunil,

    I'm sorry I wasn't clear on the third point, I intended to ask to try the three different I2C addresses, which each ADDR_EQ pin configuration.
    ADDR_EQ = Vih, 0x2C, 0x2D, 0x2E
    ADDR_EQ = Vim, 0x2C, 0x2D, 0x2E
    ADDR_EQ = Vil, 0x2C, 0x2D, 0x2E

    Regarding the path, I wanted to confirm DP130's pins 4 and 5 are connected to I2C bus, this is to discard a soldering or broken path issue.

    Have you tried a different DP130 IC?
    Would you be able to send a board for testing?

    Regards