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LM25149-Q1EVM-2100: Testing LM25148 on LM25149 EVM

Cindy Chang
Intellectual 2475 points
Part Number: LM25149-Q1EVM-2100
Other Parts Discussed in Thread: LM25148, LM25149

Dear expert,

Customer is evaluating LM25148/9 and has some questions:

1. Correct me if I’m wrong, LM25148 and LM25149 both share the same EVB which uses LM25149. If I want to test LM25148 function, I just need to disable the AEF and it behave like LM25148, is this correct? Or we should replace LM25149 IC to LM25148 IC? If so, is there anything also need to be modified on EVM?

2. I found on the VIN plane where are several small MLCC ( C17 to C22 ), are these capacitors there to act as bypass while lowering the ESL to achieve lower EMI at high frequency? If that is the case, is it necessary to include these capacitors? If not, how bad can we expect the performance to be like?

Thank you.

Best Regards,

Cindy

  • 0
    TI__Mastermind 22299 points

    Hi Cindy,

    Yes LM25148 and LM25149 are the same DC/DC controller, the only difference is AEF.

    You can disable AEF (CNFG to GND) to evaluate LM25148. Also you can remove AEF components (including C23 & R6)

    For C17-22, looking at the datasheet these are the lowest impedance around 20-200MHz.

    You can expect EMI to be worse at these frequencies with those caps removed.

    Hope this helps,

    -Orlando