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UCD9081: UCD9081 not responding on I2C after a configuration load

Sanjoy Datta1
Prodigy 40 points
Part Number: UCD9081

Hi,

I'm using UCD9081 in my design with the UCD9081 EVM software w/o any problem for a while. Recently I made quite a few changes to the design (i.e. configuration) and after a configuration upload, the device has stopped responding on I2C to the Host. I am not able to recover the configuration because even if I manually reset the device, it stops responding on I2C. I've totally isolated the device so that no other devices are powered and nothing else is connected to UCD9081 I2C other than the TI USB-to-I2C adapter. Is it possible for a user configuration to totally wedge the device and if so, how do I troubleshoot/recover the device?

Thanks

SANJOY

  • 0
    TI__Guru 60800 points

    Hi

    I suspect that what your changes make device busy to handle external things so that It can not process I2C. The key is to figure what have been changes and from there to change the external condition.

    Most time is that device is busy on handling fault conditions of the rails.  Could you ensure that there are no any fault conditions(OV or UV) on all rails so that device can be back to function mode.

    Regards

    Yihe

  • 0 in reply to yihe
    Prodigy 40 points

    Hi Yihe

    It's very difficult for me to figure out the source of the fault w/o having access to the tool since the device is not responding to any I2C.

    Is there a way to restore a 'default' fail-safe configuration?

    Thanks

    sanjoy

  • 0 in reply to Sanjoy Datta1
    TI__Guru 60800 points

    HI

    You may try to probe the voltage of all rails to see whether anyone are not within expected ranges. Do you remember what have been changed from configuration?

    The restore can be done via I2c only.

    Regards

    Yihe

  • 0 in reply to yihe
    Prodigy 40 points

    Hi Yihe

    I've attached my design file here.

    As you can see, in the design, Rail2's enable turns on when Rail3 comes up. Rail3 as well as all other Rails turn on when Rail2 comes up. What I'm seeing on actual board is that none of the Rail's enables are turning on and the UCD9081 is not responding to Dongle's I2C.

    The above might seem to be a chicken-and-egg situation but actually Rail2 is actually always ON - it is controlled by it's enable signal. I measure the Rail2 voltage (after the external voltage divider) to be 1.5V, which, after voltage scaling, should read 15V - which is above UV threshold, and should turn on all other rails, including Rail3. But I don't see any rails turning ON.

    Let me know if you have any suggestions or comments.

    Thanks

    SANJOY

    ddc_in_PSEQ_sanjoy_040920.zip

  • 0 in reply to Sanjoy Datta1
    Prodigy 40 points

    A correction to the 3rd para above:

    The above might seem to be a chicken-and-egg situation but actually Rail2 is actually always ON - it is not controlled by it's enable signal.

  • 0 in reply to Sanjoy Datta1
    TI__Guru 60800 points

    Hi

    Do you see EN toggling on any rails on the scope?

    Is the 1.5V from scope or multiple-meter? we would suggest scope instead of DMM.

    How about make the rail#2 be 2V instead of 1.5V? what's the slew rate of the rail#2 input? could you just directly connect a 2V power source to the MON2 to exclude slew rate?.

    If these do not work, you may replace the IC.

    Regards

    Yihe 

  • 0 in reply to yihe
    TI__Guru 60800 points

    Hello

    I tried your file on the EVM and do not observe any lock up on the I2C communication. I do not see anything obvious to cause the lock up.

    If you can physically access the board, please do some measurement on the SCl/SDA resistance.

    Regards

    Yihe