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DDC112 AVDD and DVDD issue

Ron Ying
Intellectual 285 points
Other Parts Discussed in Thread: DDC112

Hello,

I am having an issue in the DDC112 circuit. I am using two power sources for DVDD and AVDD separately; found the following issue:

1) when AVDD=5.00V and DVDD=4.96V, there is a huge current (about 300mA) draw from AVDD;

2) then I drop AVDD  = 4.78V, and DVDD=4.96V, then the current of AVDD is within spec.

Am I having a batch of bad DDC112s? cause I have tried 4 of them, and they behave the same.

For using separate power supplies for DVDD and AVDD, is there a requirement for AVDD <= DVDD?

Thank you,

Ron Ying

  • 0
    Prodigy 50 points

    Hi Ron,

    have you found an answer to your question?

    I'am also suffering from same issue, please let me know if you have an answer.

    Thanks,

    T. Salt

  • 0 in reply to Tarik Salt1
    Intellectual 285 points

    I have done extensive testing on DDC112 as shown below, and we found that DDC112 requires proper power sequencing in order to have it work as intended, that is, DVDD cannot be powered up first; DVDD can be powered up simultaneously with others. (sequence 1, 2, 3 meaning first, second, and third powering up):

    AVDD(5V)

    DVDD(5V)

    Vref(4.096V)

    Result

    sequence

    current

    sequence

    current

    sequence

    current

    1

    15mA

    2

    0-2mA

    3

    2mA

    OK

    3

    16mA

    2

    1

    2mA

    OK

    3

    >700mA

    1

    2

    >220mA

    N.G

    2

    >300mA

    1

    3

    >500mA

    N.G

    1

    15mA

    3

    2

    0-2mA

    OK

    2

    14mA

    3

    1

    0-2mA

    OK
  • 0 in reply to Ron Ying
    Prodigy 50 points

    Thanks a lot Ron!

  • 0 in reply to Tarik Salt1
    TI__Guru 65190 points

    Tarik,

    We took the original conversation of this issue offline and tried to reproduce Ron's issues on our Bench. Unfortunately we were not able to reproduce his issue. Fortunately Ron has resolved his issue and was able to use the part as he wanted to. We are looking into the issue more and will let you know what we discover. 

    Thanks and Regards,

    -Adam Sidelsky

  • 0 in reply to Adam Sidelsky
    Prodigy 50 points

    Adam,

    Thanks for your Response. Conceptually I have a similar Problem but the answer  I look for is different. I originally posted my Problem also in this Forum, but someone told me to post it under High rel Forum. I did not really understand why but I did it. So please refer to my original question under high rel Forum, if you don't mind.

    DDC112 Supply requirements

    Thanks,

    Tarik