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LM5122EVM-2PH: Temperature rises

Jingguo Wang
Intellectual 960 points
Part Number: LM5122EVM-2PH

My circuit is built according to LM5122EVM-2PH, VIN=12V,Vout=45V, Load=3A, f= 350kHz,  A large temperature rise(about 80 degrees Celsius)  was found during the test in MOSFET and inductance. What may causes this?

  • 0
    TI__Genius 15955 points

    Hello Jingguo,

    Thanks for reaching out to us via e2e.

    Is this thread related to the other one that you had filed one hour later?
    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1123840/lm5122evm-2ph-change-output-voltage
    Is this the same project?

    Please look at the other thread for some explanation.

    Best regards,
    Harry

  • 0 in reply to Harry Hofner
    TI__Intellectual 960 points

    Hello, thank you for your reply.

    The temperature rise data above is provided by our customer, and I wonder if this temperature is reasonable with the reasonable efficiency.  Their output voltage is 45V, the load is 3A, the operating frequency is 350K, and the circuit parameters are reasonably designed. The another question is the same project as this.  I want to change the frequency of EVM to simulate the customer's application environment .

  • +1 in reply to Jingguo Wang
    TI__Genius 15955 points

    Hello Jingguo,

    Now I understand your approach.
    You have a TI EVM on hands and want to tweak it to get close to the customers application and then compare temperatures etc.

    To be honest, I don't know how to judge the temperature rise, it depends on many factors.
    So I am really happy that you want to do that experiment.

    To change the output voltage, simply modify R32 of the 2-Phase EVM / the lower resistor of the feedback divider.
    This way you do not influence the compensation network.

    Then you can increase the frequency in a few steps from 250kHz to 350kHz to see what happens.

    The compensation will probably no longer fit, but as long as you do not apply any rapid changes of the load or the input voltage is not too critical.

    Best regards,
    Harry