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ADS5295: Bad Test Pattern On A Signle Channel

yossi krispine
Prodigy 10 points
Part Number: ADS5295

Hi,

We are using ADS5295 in one of our systems. In a few units we encountered some abnormities.

We are using the ADS5295 test patterns for a word alignment calibration during system start-up.

We set registers 25h and 26h for a test pattern of 0xFC0. All ADS5295 channel do output the desired pattern beside one channel that show a single reverted bit and generate the pattern 0xFC2.

Note that the corrupted pattern for this channel does not occur for any programed pattern, for instance for patterns 0xCCC & 0XCC3 all the channels produce the same and correct pattern.

See a scope snapshot enclosed for illustration – CH1 is the bad ADC channel and CH2 is a good one.

What can be the cause for such an issue?

  • 0
    TI__Expert 6790 points

    Hi.

    I am sorry about your issue. This looks quite weird that only one channel is giving corrupt output for just one test pattern. Let me check this with our design team and I shall get back to you as soon as possible.

    Can you confirm the below questions:

    Where are you probing this output? Is it deserialized data on the FPGA?

    Thanks & regards,

    Abhishek 

  • 0 in reply to Abhishek Vishwa1
    Prodigy 10 points

    hi Abhishek,

    Thanks for the answer.  

    i'm probing the signal using an oscilloscope on the ADC output pads. 

    oscilloscope pic enclosed to the post. 

  • 0 in reply to yossi krispine
    TI__Expert 6790 points

    Hi Yossi,

    A few questions:

    I understand that you are writing a 12 bit custom pattern on the output, just for sanity check, can you verify the settings you are writing in Reg 0x25h and 0x26h?

    Do you see similar problem in other devices as well or is it the only one showing this symptoms?

    I checked with my team and they think this is not acceptable behaviour, can you connect to your local quality engineer from TI, who can support you further to have this device recalled?

    If in case you cannot find the relevant person, kindly send us a mail on support_us_afe_tx@list.ti.com, we will connect you and help you further.

    Thanks & regards,

    Abhishek

  • 0 in reply to Abhishek Vishwa1
    Prodigy 10 points

    “I understand that you are writing a 12 bit custom pattern on the output, just for sanity check, can you verify the settings you are writing in Reg 0x25h and 0x26h?”

    We write 0x8013to 25h and 0xf000 to 26h.

    “Do you see similar problem in other devices as well or is it the only one showing this symptoms?”

    We see the same symptoms at a few systems but we are not in mass production just yet so we didn’t manufacture a lot up to this moment.

    “I checked with my team and they think this is not acceptable behaviour, can you connect to your local quality engineer from TI, who can support you further to have this device recalled?”

    Already contact Ori Marom, Israel local rep who’s responsible for my company account.