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ADS54J60: ADS54J60 DC correction effecting LSB (bits stuck) and 14-bit instead of 16-bit resolution

Jiri Kral83
Prodigy 90 points
Part Number: ADS54J60

Hello (Jim probably :),

I am facing a problem alike: http://e2e.ti.com/support/data-converters/f/73/t/598565#pi320098=2 or http://e2e.ti.com/support/data-converters/f/73/p/712929/2722985

The detail description is in the attached presentation.

General description problem 1)
One out of four interleaving cores misbehaves and its LSBs are getting stuck for periods in time. The behavior can be influenced by DC offset correction and digital gain changes, yet I did not succeed in fixing it. Freezing the IL correction seems to have no effect.

General description problem 2)
All four interleaving cores provide what seems to be 14-bit data with the 2 LSB of the 16 bit word being either random or influenced by the problem # 1. The JESD ILAS config sent by ADC reports N = 14!!! N* = 16.

Thank you for advice. This seems to be somewhat a common issue. What was the fix for the previous reports that I linked?

Sincerely

- Jiri

ads54j60_problems.pdf

  • 0
    TI__Expert 4880 points
    Jiri,

    We have forwarded your question to a device expert and they should get back with you shortly.

    Yusuf
  • 0
    TI__Guru* 91947 points

    lower bit issue.docxJiri,

    Please see the attached document regarding this issue.

    Regards,

    Jim

  • 0 in reply to jim s
    Prodigy 90 points

    Dear Jim,

    thank you for answer. If you check the initial document that I provided with the detail analysis of the problem, you will find the power-up sequence that I use. In there it is written that I do write the bit to 1 already. Naturally, I tested putting the OVR to the LSB before posting, which gave the expected behavior with exception at one core that you describe (one core bit was not on LSB). In the report that I send, the OVR information is turned off, hence only data is expected.

    Please look into the issue that I am reporting as there are multiple signs of the ADC either being 14-bit instead of 16 (N=14 in ILAS) or some other issue. I need to know if this is a "design property" of the ADS54J60 or if I have a faulty batch. I have scanned your forums before posting and tested all suggestions you provided to others having similar issue (none of those was resolved as far as I remember).

    Sincerely
    - Jiri

  • 0 in reply to Jiri Kral83
    TI__Guru* 91947 points

    Jiri,

    I noticed this as well when I captured ILA data. This may be a bug. I am checking with the design team now.

    Regards,

    Jim