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LM5116 Heating and turns off

Akshay Deshmukh1
Prodigy 20 points
Other Parts Discussed in Thread: LM5116

Hello,

I have built a regulator based on LM5116

Vin from 24 to 80 V. Vout  is 15 V. Iout is 2 A.

No load is connected initially.

The regulator works well when Vin is from 24 to 40 V. But, when I ramp more than 40 V, the LM5116 gets heated up and stops working (Vout = 4.6V).

I have built the circuit using TI Webench on a general purpose PCB. So the layout is not to the mark as per the datasheet.

Attaching the Webench design file.

1273.webench 15V.pdf

Waiting for your kind reply.

  • 0
    TI__Mastermind 46141 points

    Hi 

    When you ramp the input voltage more than 40V, Only the LM5116 temperature gets up  ? or MOSFET temperature gets up as well ? 

    Also, please let me know your switching frequency and MOSFET part number. 

    Regards,

  • 0 in reply to EricLee
    Prodigy 20 points

    Hi,

    Thank you very much for your quick reply.

    Yes, only LM5116 temperature gets up and IC gets damaged. After replacing the IC no other component found failed. No temperature variation in Mosfets.

    Operating frequency is about 300KHz. Mosfet part is  BSZ160N10NS3 G, as suggested in the Webench BOM.

    Regards

  • 0 in reply to Akshay Deshmukh1
    TI__Mastermind 46141 points

    Hi 

    If you test again at >40V input voltage when EN = HIGH and UVLO = LOW, you can distinguish whether the issue is caused by switching noise or the high input voltage itself. 

    If there is no issue when UVLO=LOW, please check the switching spike at SW node and try a RC snubber if needed. 

    Regards,

  • 0 in reply to EricLee
    Prodigy 60 points
    Hi Eric

    I have some problems with a LM5116 design. One of the circuits i use is heating up immediately. Supply is 24V, current drawn from Vin is 90-100mA which is very much. Frequency i setted up is only about 55 kHz because i have to use Low Rdson transistors (5nF gate)
    I don't understand why is heating up; this is the third IC i am putting on this design; the others had some other issues (stability), but none heating...