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TPS40210 - Reliability problems

carlo agrusti
Prodigy 40 points
Other Parts Discussed in Thread: TPS40210

I used TPS40210 to design a 2A boost converter, VIN=22-26V, VOUT=45V. Switching frequency is 600kHz, and I used a AUIRF3710Z as switching mosfet; everything is fine, ripple voltage and regulation are really nice also with inductive loads, and overcurrents are correctly treated. Also converter ~ENABLE function works properly. As regards thermal aspects, both controller and mosfet remain at very low temperature - even lower than expected. The only problem I encountered up to now - and it is a big problem - is that some boards are coming back with the mosfet broken and/or with the 40210 broken; in one case the TPS40210 is also shorted to ground. At this point I have no clue about this problem; now I'm testing some boards with a "lighter" mosfet - an IRFR1018 - but even boards with original one never failed during laboratory tests.

TIA for any suggestion,

Carlo

  • 0
    TI__Mastermind 35165 points

    Hi Carlo,

    Can you share a schematic please?

    Also a few more questions to understand the condition of the failures.
    1. What pin do you see shorted to ground on the TPS40210?
    2. Does replacing the failed component solve the issue?
    3. Are the failures occurring at first power up or over time?

    Regards,
    Anthony

  • 0 in reply to Anthony F
    Prodigy 40 points

    Hi Anthony,

    thank you for your response. Please find attached pdf with schematics 1680.boost.pdf

    Regarding your questions:

    1. In one case only I found VDD (pin 10) shorted to ground

    2. Yes, until a new failure

    3. No, sometimes they happens after few days, sometimes after hundreds hour of service, sometimes they never happen.

  • 0 in reply to carlo agrusti
    TI__Mastermind 35165 points

    Hi again Carlo,

    A few more questions.

    Can you share your layout? Did you notice anything unusual in your evaluation during any of the transient conditions such as startup or load changes? Some key signals I am curious of are the switching node (Drain of FET), gate drive signal and output voltage. Is there any way you can point to a specific event when the failures occur?

    Nothing jumps out when looking at the schematic. One comment is R7 is a bit larger than I recommend but this should not cause the part to fail. The only concern here is tripping current limit during start up stopping the supply from turning on. Accounting for tolerances to avoid issues the maximum recommended value is 24.9kΩ.

    Regards,
    Anthony