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LM5170EVM-BIDIR: CCCV testing observe LDO and logic getting damaged

John Chou62
Intellectual 2070 points
Part Number: LM5170EVM-BIDIR
Other Parts Discussed in Thread: LM5170

Hi Team,

my customer is testing with the LM5170 EVM board.

with inputs at 48V and output 300W (14.4V ~20A)

it's observed on two EVM board that the two LDO was damaged (no output or output abnormally high) after some CCCV testing and they scoped the FET's behavior, did not touch the LDO circuit area

the two LDO are U3 and U4, TPS7950DBVR、TPS70933DBVR

on one of the board, the logic device SN74LV1T32DBVR was also found damaged (always output high) after some testing .

we'd like to check with the design team on the observation and whether any recommendations can be provided

Thanks

  • 0
    TI__Guru* 78400 points

    Hi John,

    Thank you for reaching out.  The description of what happened is not clear.  They must did something wrong by shorting U3 or U4 output.  Most probably the LM5170 is still working. 

    First, make sure the 10V bias supply is still alive. If not, you will need to replace all the three ICs: U3, U4 and U5.  You must see 10V, 5V and .3V established before you can operate the EVM.

    Another option is, remove U3, U4, (assuming U5 is working, if not, you will need to disconnect J4), and externally supply 3.3V and 5V to the corresponding pins of J17 (the 60 pin connector).  

    A quicker solution is to order a new EVM, follow the user's guide instruction when handling the EVM during test.

    Best Regards,

    Youhao Xi, Applications Engineering