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TPS61033: Part burns and becomes unusable sporadically sometimes after days

Dima
Prodigy 30 points
Part Number: TPS61033
Other Parts Discussed in Thread: BQ25628E,

Tool/software:

HI,

I am using 2 DCDC converters TPS61033 and TPS6282xx that are fed from the output of BQ25628e.
While the TPS6282xx has never ceased functioning for me I have a recurring problem burning the TPS61033.
I would be happy for any advice and input where I might have errors, attaching my schematic:


Regards,
Dima

  • 0
    TI__Genius 16910 points

    Hi Dima,

    Can you provide your test condition and waveform when damage occurred? Like Vin, Vo, SW, IL?

    Looking forward to your reply. Thanks.

    Aurora

  • 0 in reply to Aurora Tie
    Prodigy 30 points

    I don't have the waveform for when the damage occurred. However, I took a look at the Voltage at the points you mentioned during operation and noticed that perhaps the issue is at the SW, when both Vin and Vsys seem to look good. attaching pictures:

    V_sw



    V_in



    V_sys



  • 0 in reply to Dima
    TI__Genius 16910 points

    Hi Dima,

    Did you test your SW with full bandwidth? If so, it seems normal, because under full bandwidth testing, you will see some rings when the MOSFET switches, which is related to some parasitic.

    What is the current failure rate? Which system is most likely to fail during testing? Also, it would be helpful if you could provide a layout for this part.

    Thanks.

    Aurora

  • 0 in reply to Aurora Tie
    Prodigy 30 points

    Hi Aurora,
    If you what mean by full bandwidth is high current then no. I am testing at a currents around 100mA.
    I did see in the spec that a -1.4V at the SW is beyond the absolute maximum rating for Voltage range at terminals - can this be the problem?

    Vsw with the current drawn by the circuit:



    Attaching the layout:


    Vin with a better resolution:



    Vout with better resolution:



    Best regards,
    Dima

  • 0 in reply to Dima
    TI__Genius 16910 points

    Hi Dima,

    The full bandwidth I'm referring to is the oscilloscope setting. Also, whether the SW is tested with the minimum loop or not may affect the maximum and minimum values ​​you see.

    In addition, why is there such a large ripple on your Vin waveform? Generally speaking, Vin should be a relatively stable DC voltage. Can you increase the input capacitance of the TPS61033?

    Aurora