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LMK04828BEVM: LMK04828BEVM

mike holmes
Prodigy 30 points
Part Number: LMK04828BEVM
Other Parts Discussed in Thread: USB2ANY, LMK04828

I had the board working fine locking to a 100 MHz clock input and outputting a 400 MHz clock. Then lightning struck ... somewhere ... lost power ... now the LMK04828BEVM is drawing about twice the current that it was (i.e., now about 0.75 A, was about 0.38 A) ... the PLLs are not locking and I've lost the ability to communicate via USB2ANY. I didn't find any fuses. I am posting this in case anyone has any ideas on what could've gone wrong - besides the lightning and lack of UPS.

I'll be purchasing another LMK04828BEVM ... and a UPS ... now that I am working from home, I guess I need one, obviously.

  • 0
    Prodigy 30 points

    correction : USB2ANY comm still working and am able to load a config file, to no avail (i.e., PLLs don't lock, still excessive current draw compared to before)

  • 0 in reply to mike holmes
    TI__Mastermind 33690 points

    Hi Mike,

    Sounds like something got fried... The two things most likely to pop are the IC itself and the VCXO. You can quickly test if the VCXO is the problem by disconnecting the power to it (just remove R18) - the VCXO should only draw about 25mA normally. You could also try desoldering the LMK04828 and replacing it with a new part.

    You also might want to check that the IC supply pins are receiving 3.3V by monitoring the output of the 3.3V LDOs (check with a multimeter). If the LDOs are fried, those can at least be bypassed.\

    You can also try setting the Powerdown bit from the TICS Pro user controls page, which should drop the board to a low-current state. This might help identify if all the power is being dissipated in the IC or elsewhere.

    Regards,

  • 0 in reply to Derek Payne
    Prodigy 30 points

    Hi Derek,

    Thanks for the quick response and suggestions. I'll give them a try whenever I can return to work and use proper de-soldering stuff. In the meantime, I've ordered another board so that I can get backup and running quickly.

    Best,

    Mike