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TPS62130 why broken?

Toshiaki Fujikura
Prodigy 60 points
Other Parts Discussed in Thread: TPS62130

Dear Members,

I have a problem of TPS62130 broken frequently.  

The adopting conditions are

The input  voltage is 12V.

The load current is 1.2A.

The switching frequncy is 2.5MHz.

Coil inductance is 2.2uH.

Output capacitance is 22uF ceramic.

Input capacitance is 10uF ceramic.

I have  two broken chips that SW pin -GND pin shorted and one chip that non-switched pulse(non HI voltage).

All of these broken chips were suddenly death.

I had tried to investigate the cause of broken as follows,

1. I checked the temperature of the  chip top. That is 55 degree Celsius.

2. Output voltage ripple is 10mVpp. Output voltage is 5.5V.

3. The overshoot and undershoot voltage are 1Vp on switching dead time. The pulse width is 5nsec.

How can I get the cause of the broken?

How should I investigate any other item?

 

 

 

 

  • 0
    TI__Guru**** 150900 points
    The most common cause of a SW to GND short is poor PCB layout, especially with the input cap. Excessive inductance in this path can overstress any SMPS. You can order the EVM to test a known good layout.
  • 0 in reply to Chris Glaser
    Prodigy 60 points
    Thank you for your suggestion. Let me know how to ask you my reviewing my layout.
  • 0 in reply to Toshiaki Fujikura
    TI__Guru**** 150900 points
    Thanks for sending the layout. It is difficult to tell the where the components are since everything is black. As well, it seems that the reference designators of the caps in the parts placement don't match the schematic? Finally, the parts placement and actual copper and seen from different directions and so appear reversed? Did I understand this correctly?

    It would help to see a layout image with the component outlines. There does not look to be enough space for that inductor, for example.

    Are there thermal vias under the IC?

    Can you explain what test you were running when these devices failed?
  • 0 in reply to Chris Glaser
    Prodigy 60 points

    Thank you for your response.

    Sorry for my poor document.  I provide with the report for you.

     Your Question's answer

    1, Parts Layout is reversed against pattern. 

    2. There are Thermal vias under IC. Yes.

    3. This IC's load are DA converer and AD converter each two pieces.

    I had found these devices failed when these AD converters and DA converters were fully running.

    This consumption current is 1.2A.

    4. Give me a comment switching waveform on my report.  Do they have any problem?

    Best Regards

    Thank you

    Toshiaki FujikuraTPS62130defectreport.xlsx

  • 0 in reply to Toshiaki Fujikura
    TI__Guru**** 150900 points
    Thanks for sending these measurements. They are ok.

    Can you confirm that what is labeled as C128 in your parts placement image should be C129 in the schematic? And should C126 really be C128?

    Is it possible to measure Vin, Vout, inductor current, and SW when an IC fails? You can probably trigger on a falling Vout.

    Is there any extra Cout on the bus downstream?