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TPS767D301-EP: Reset Output

Naveen Devara
Prodigy 80 points
Part Number: TPS767D301-EP

Hi,

I had followed eZdspTM F28335 design for powering up TMS320F28335SPTPQ in my product. It is the first time power up of my board.

As per the IC functionality, reset time out is 200ms. In my design initial power up sequence is fine. But after that, reset is not stable. It has to be at 3.3V constantly but it is toggling at a period of 4.5 ms.

Signals is like 4.5ms at 3.3V level and 15uS at 0V level and again goes to 4.5mS at 3.3V level. 

Please help me to resolve the issue. 

  • 0
    TI__Mastermind 20045 points
    Hello Naveen,

    Are you able to monitor the power rails to the TMS device and see if there is a power supply issue? Also if you are able to upload your schematic so we can see if we find any issues that would be helpful.

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    Prodigy 80 points

    Hi Kyle,

    Thanks for the reply.

    I have monitored the power rails and found OK. I suspected power rails initially, but if it is so there must be reset time out of 200ms gap. but in my case it is only 15uS and later 4,5mS. I attached schematics. Please reply.

  • 0 in reply to Naveen Devara
    TI__Mastermind 20045 points
    Hello Naveen,

    Thanks for the schematic. I know you said the power supplies look good (and I agree with your assessment that if they fail we would expect a 200ms reset), but are you able to upload waveforms of Vin, Vout, and Reset as well? It would also be useful to see an AC coupled Vout so we can see if there is any minor change on Vout. Hopefully the waveforms plus the schematic will help us figure out what is going wrong.

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    TI__Mastermind 20045 points
    Hello Naveen,

    I'm just follwing up on this question to see if you have been able to obtain the requested waveforms.

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    TI__Mastermind 20045 points
    Hi Naveen,

    I'm going to close this thread for now. Feel free to make another post by selecting ask a related question if you still need help.

    Thanks,
    Kyle
  • 0 in reply to Kyle Rakos
    Prodigy 80 points

    Hi Kyle,

    I'm sorry for delayed response. I could not share waveform with TI since I didn't capture them. But I found the answer i believe. It is due to internal watch dog timer. WDT is setting it to low 15uS. Once I gave trst# high, I could see clean reset signal. Thank You so much for supporting.

  • 0 in reply to Naveen Devara
    TI__Mastermind 20045 points
    Hi Naveen,

    Thanks for following up and letting us know the solution. I'm glad you were able to get it working.

    -Kyle