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Original question:

LM26420: LM26420XMH/NOPB failure

LM26420: LM26420

TheLam Nguyen
Prodigy 220 points
Part Number: LM26420

Ladies and gentlemen,

I'm currently using LM26420Q1 in my design and wondering if I can parallel the outputs of the same output voltage to have higher current output to the load. My intention was using 2 separate but the same value of the inductors for both channels. However, using only one resistors network of voltage divider for the Feedback pins on both channels. 

  • Have anyone done this before
  • Is there any issue of paralleling output of both channel without using ORing diodes
  • What is the impact to the reliability of the part by doing this 

Please advise on this or point me to the right direction how to achieve this task. I know for sure some will ask why don't just use the part with higher out current rating. The answer to that is we've some environmental testing with this part and it's passed so it's very costly to move to different part and repeat the test again. Any input/suggestion is much appreciated. Thank you and have a wonderful Fri all.

Best Regards,

TLN

  • 0
    TI__Genius 13160 points

    Hi TLN,

    This doesn't look possible to me. Even if you connect the same feedback network externally, there can be some slight differences in the internal reference voltage and loop between both the converters. This can cause the loads to be unbalanced between both DC-DCs and in the worst case one DC-DC sources and the other one can end up sinking the current. My recommendation would be to move to a higher current part.

    Best regards,

    Varun

  • 0 in reply to Varun John
    Prodigy 220 points

    Hi John,
    I suspected the same but want to have some sort of confirmation from the community. Anyhow, that configuration doesn't seem to be a good/common practice. Thus I should not pursue this approach and find different part instead. Thank you very much for your inputs and have a wonderful day.

    Best Regards,

    TLN