• State
  • Locked Locked
  • Replies 2 replies
  • Subscribers 97 subscribers
  • Views 238 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

L138, TPS65023, DSP side doesn't power up correctly once in awhile.

John Fielden
Prodigy 205 points
Other Parts Discussed in Thread: TPS65023

Hi, we've got a custom board with an OMAP L138 powered by a TPS65023.  We followed the example design for the TPS portion from SLVA340.

In general it works.  But, if the board has been turned off for a few minutes before power is applied, there's a really good chance that the DSP will not communicate with the ARM.  The ARM works and boots as normal, but once we get to the DSPlink, the ARM applicaiton hangs.

When the problem occurs we see that the board draws about 100mA more current than it should on power up.  If we see this power condition, you are 100% guarateed to have an unresponsive DSP.  If I power cycle the board a couple of time I can get it to the point where the current is normal and everything works fine.

I'm guessing that it has something to do with the power-up sequence, or a noisy supply.  We are following the connections from SLVA340 strictly, so I think the power-up sequence is correct.

Has anyone else seen this issue.

Thanks,

John Fielden

  • 0
    Prodigy 205 points

    I'm poking around on the circuit.  I find that when the DSP failure occurs that the output voltage on VDCDC2 is not 1.8V like it is supposed to be, but is actually closer to 3V!  The DEFDCDC2 is tied directly to ground.

    John

  • 0 in reply to John Fielden
    TI__Guru 62975 points

    John,

    Do you have a local FAE/sales office that you can contact about this?

    If possible, try to add some load to the 1.8V supply by one of the following methods to see if the 1.8V supply behaves as expected:

    • Place a 10-ohm pull-down resistor on the 1.8V supply to GND
    • Place a triple-stack diode on the 1.8V supply to GND
    • Use another PMIC or external supply that can regulate the supply by sinking current

    -Tommy