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TPS53681: Non-monotonic rise at power-up.

Christopher Hogan
Prodigy 10 points
Part Number: TPS53681

I have (2) 0.9V rails that use TPS53681RSBT and CSD95490Q5MCT

 

The rails have non-monotonic rise at power-up that does not seem correct. Scope images below:

It seems that the rail is potentially unstable at power-up. Could this be corrected by changing compensation values? Or, what else could cause this issue?

  • 0
    TI__Expert 8960 points

    Hello Christopher,

    I will look into this and get back to you early next week.

    Thanks,

    Travis

  • 0 in reply to Travis Williams
    TI__Expert 8960 points

    Hello Christopher,

    I wasn't able to replicate this issue in the lab; I got a fairly clean start-up using the TPS53681 EVM. I would recommend modifying the loop compensation parameters and the rise time to see if it has an effect.

    Looking at your scope shot, the issue seems more like a hiccup than the ringing associated with instability. As long as switching transients at full voltage don't cause substantial ringing, and your load isn't affected by the starting hiccup, you might be able to ignore the issue.

    Thanks,

    Travis