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TPS62400 Sw-node over/undershoot voltage

Go
Genius 4220 points
Other Parts Discussed in Thread: TPS62400, TPS62240

Hi,

My customer in now evaluating their board using TPS62400, and they found the over/undershoot voltage

at sw-node (measuring with spring grounding probe. please see the attached waveform.)

and they also found the over/undershoot voltage at sw-node on the TPS62400 EVM.

In the TPS62400 D/S P15 Figure29 and 30, we can see them as well.

So, Is the over/undershoot voltage at sw-node inherent problem in TPS62400?

or is it no problem? (especially undershoot, seems to be below the absolute minimum voltage for Sw_node(-0.3V))

Thanks

Go 

TPS62400_Sw_Node_waveform.xls
  • 0
    TI__Guru*** 148650 points

    Please see this app note, located on the product page: http://www.ti.com/lit/an/slva494a/slva494a.pdf 

  • 0 in reply to Chris Glaser
    Genius 4220 points

    Hi, Chris

    Thanks for the info.

    So if the over/undershoot is seen in the TPS62400 EVM with measuring proper measurement technique,

    Does it mean that there are some improvement of layout on TPS62400 EVM?

    Go 

  • 0 in reply to Go
    TI__Guru*** 148650 points

    I'm not sure that I understand your question.  The app note should have conveyed that such over/under shoots are normal and expected and not an issue.

  • 0 in reply to Chris Glaser
    Genius 4220 points

    Sorry for the confusion.

    See in the App note Figure 6 , there are smaller over/under shoots in TPS62240 EVM,than those in TPS62400 EVM that the customer measured.

    So I think there are some difference of layout between these 2 EVMs, and there are some improvements of layout in TPS62400 EVM,

     if these waveforms were measured properly.  

  • 0 in reply to Go
    TI__Guru*** 148650 points

    Those are different devices, so their performance varies.  But the basic behavior is the same for all bucks, even it is manifested with slightly different voltages/timings, etc.