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LMR38025QEVM: LM38025 EVM damage

Jimmy WANG
Genius 4165 points
Part Number: LMR38025QEVM


Tool/software:

Hi team,

My customer evaluated LM38025 for their new design. but they change some settings as below.

Vin=60V

Vo=12V and change the inductor to 10uH or 22uH. (spec as below)

The customer tested short circuit test 2~3 times then EVM damage. 

They use a 200R as load and parallel a switch as  a short test device.

After 2~3 times then IC damage. test waveform below. you will see a spike after protection occurs.

Customers think IC damage caused the spike. Could you give some suggestions? thanks 

CH1 is Vin

CH2 is Vo

CH3 is Io

  • 0
    TI__Mastermind 31315 points

    Hi Jimmy,

    Sorry to hear about the damage.

    In the datasheet, it is mentioned that the output voltage must not be allowed to fall below 0V. The operating conditions table mention the minimum output voltage is 1V, any lower we cannot guarantee performance.

    Can you re-do the test with an electronic load operating in CV Mode, and forcing the CV voltage to be such that the FB pin voltage is around 0.3V to 0.4V and let me know if the issue is resolved?

    Thanks,

    Richard

  • 0 in reply to Richard Fu22
    Genius 4165 points

    Hi team,

    I don't understand.

    Testing process of a power supply ~ Short circuit protection must be tested.
    You can't let customers test in CV mode. 

  • 0 in reply to Jimmy WANG
    TI__Mastermind 31315 points

    Hi Jimmy,

    Sorry for clarifying. I'm wondering if damage is occurring because of how the short circuit test is implemented, because as you can see with the output voltage waveform, VOUT goes below 0V. 

    When I suggest CV mode, it is an easy way to tell if device is entering hiccup mode as planned. You may also just increase load current to see device enter hiccup mode. 

    Let me know if I'm making sense. 

    Thanks,

    Richard