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TMS320F28335 Failure DSP

marilingaiah nl
Prodigy 175 points
Other Parts Discussed in Thread: LM2830, LM1086, OPA4340

Hi all,

Does anyone know what could cause supply Pin short to ground on DSP.

This DSP chip sucks. this is not a reliable one.

Failure modes

a. This DSP is shorting the 3.3V to Ground and going bad frequently on our board. In some cases both the 3.3V and the 1.9V are shorted to GND. When we replace the DSC the shorts disappear.

b. On some Boards DSC-ADC is going bad frequently on our board.

Test Conducted.

I was thinking this could be because of ESD, for our confirmation, I did ESD test on the board.

DSP was working fine even up to +/- 30KV Air Discharge and Contact Discharge.

if anyone come across similar situation. Please help me.

Regards

Marlin

  • 0
    TI__Expert 7885 points
    Hello Marlin,

    It sounds like the F28335 is being electrically over-stressed in some manner. Please answer the following:

    1. Which supply ICs are used to supply the 3.3V and 1.9V to the F28335?
    2. Are there any digital pins which have signals applied to them prior to the VDDIO rail being powered to 3.3V?
    3. Are there any analog pins which have signals applied to them prior to the VDDA rail being powered to 3.3V?
    4. Would you mind sharing your schematic so that we can review it?
    5. Have you tested continuity from supplies to GND on a board with a good device?

    Best Regards,
    Adam Dunhoft
  • 0 in reply to Adam Dunhoft
    Prodigy 175 points
    Hi Adam,

    thanks for your reply. Please see my response below.

    1. Which supply ICs are used to supply the 3.3V and 1.9V to the F28335?

    Ans:
    3.3V is Generated from LM2830 IC
    1.9V is Generated from LM1086 IC

    2. Are there any digital pins which have signals applied to them prior to the VDDIO rail being powered to 3.3V?

    Ans: NO

    3. Are there any analog pins which have signals applied to them prior to the VDDA rail being powered to 3.3V?

    Ans: NO

    4. Would you mind sharing your schematic so that we can review it?

    Since its confidential i can't share it on the form. Can you please share your mail id.

    5. Have you tested continuity from supplies to GND on a board with a good device?

    Yup did check the continuity bewteen Supplies to GND and der was no short observed.


    Regards
    Marlin
  • 0 in reply to marilingaiah nl
    TI__Expert 7885 points

    Hi Marlin,

    You can email the schematic to me.

    What are the voltage/current levels of the ADC inputs in your application?

    Best Regards,
    Adam Dunhoft

  • 0 in reply to Adam Dunhoft
    Prodigy 175 points
    Hi Adam,

    Thanks for your email id.

    What are the voltage/current levels of the ADC inputs in your application?

    Voltagle Level(on ADC input) = 1.2V

    Current Level => Adc inputs are driven by OPA4340 OpAMP Buffer.


    Regards
    Marlin
  • 0 in reply to marilingaiah nl
    Prodigy 175 points
    Hi Adam,

    I sent schematic to your email id on 11/16/2016, hope you received the same.

    Please do needfull.

    Regards
    Marlin
  • 0 in reply to marilingaiah nl
    TI__Expert 7885 points

    Hi Marlin,

    I am currently reviewing the schematic with my team to see if there is anything which stands out. I will try to have a response for you tomorrow.

    Do you know if you are experiencing any voltage/current spikes on the VDDIO or VDD supplies during operation? It sounds like the device supplies are being over-stressed.

    Best Regards,
    Adam Dunhoft

  • 0 in reply to Adam Dunhoft
    Prodigy 175 points

    Hi Adam,

    Waiting for your resopnse.

    I did scoped the VDDIO and VDD supply lines and i don't see any spikes on it. Supply lines were stable.

    Regards

    Marlin

  • 0 in reply to marilingaiah nl
    TI__Expert 7885 points
    Hi Marlin,

    Thank you for your patience.

    My team reviewed your schematic and did not see anything that concerned us. Is it possible that you have a power sequence issue where signals on the GPIOs or Analog pins are brought up at any point prior to your supplies (even if only for a short time)?

    At this point, it may be best to send the devices which are no longer working back to TI so that we can perform a failure analysis. I believe you would have to contact your distributor to get the return process started.

    Best Regards,
    Adam Dunhoft
  • 0 in reply to Adam Dunhoft
    Prodigy 175 points
    Hi Adam,

    thanks for the schematic review and feedback.

    For your information. Some where in 2015 we did sent failure parts to TI for analysis(last year failure rate was minimal). TI reported failure was because of EOS(We were not sure what was causing EOS on DSP).

    But we are seeing lot of failure parts this year, around 25 Parts. this is making us worried and to dig further on this issue to understand what is going wrong.

    I will share the TI analysis report which sent to us last year.

    Let me know what can be done further on this issue.

    Regards
    Marlin