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TPS62110 - EOS on downstream capacitors

Juan Mindiola
Prodigy 20 points
Other Parts Discussed in Thread: TPS62110

7115.C149Ckt.docxHi,

I've attached a ckt built around TPS62110.  This is in use in our design, yet after some recent testing C149 on the output of this converter was found to be damaged by EOS.  We are having trouble figuring out what could have caused the EOS condition in this ckt.  Do you have any experience with this type of problem?  Some people are suggesting the converter is going into oscillation somehow or that there is not enough capacitance to handle the 3 inductors once we apply the voltage, temp and tolerance deratings.  Ripple was measured on another board to be about  0.425Apk-pk. We don't see this problem frequently at all, but it is a solid electrical failure we would like to sort out before mass production.  Thanks! JM

  • 0
    TI__Guru**** 150870 points

    It is very rare that ceramic capacitors fail.  Is C149 a ceramic?

    Yes, the TPS62110 could be unstable with all the secondary filters.  You need to look at the SW node and output voltage and see if they are oscillating while your system is running.

    If you want to save some money, TI has many LDOs to offer that might replace that LT LDO.  You can post your specs in the linear regulators forum and we can find one for you.  We have our new low cost TLV7 family.

  • 0 in reply to Chris Glaser
    Prodigy 20 points

    Yes, C149 is ceramic.  That is one reason why we are scratching our heads a bit on this.  The fact that C149 is rated at 16V whereas the other parallel caps are only 10V makes me think the oscillation possibility is more likely.  I think the oscillation may be happening only on some units with some kind of tolerance stack-up and a particular operating mode, that is why we don't see it when we measure it.  I'm not sure they are ready to try a new part yet, so I have to get a bit more evidence of a problem, but I'll try to put something on the specs together soon.

  • 0 in reply to Juan Mindiola
    Prodigy 170 points

    I'm curious -- was this problem solved?  If so, what was the solution?  Thanks.