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LM5116-12EVAL: LM5116 Change EVAL Board to Input: 40-64V - Output:34V/12A

Marcel Vogelsang
Prodigy 20 points
Part Number: LM5116-12EVAL
Other Parts Discussed in Thread: LM5116

Hello,

I got a LM5116-12VEVAL/NOPB Board (see attachments) for testing. I used the Webench Tool to create a circuit for my application: Input: 40-64V - Output: 34V/12A (see attachments).

To reach my designated output voltage, I only changed the RFB2/Rfbb resistor from 10.7kOhm to 33kOhm (RFB1 is still 1,21kOhm). But when I turn on the voltage, the LM5116 breaks.

I know that there are more differences between the Board and the Webench Design like the Input&Output capacitors but I hoped that I could start by just changing the resistor.

Could you help me getting my application started?

Many thanks in advance,

Marcel

  • 0
    TI__Guru 64515 points

    If you are using the TI EVM for your testing, you will have to get most of your components close

    to the Webench design.  Especially, you will need to change the output capacitors

    to a higher voltage rating for your 34Vout.  The ramp components will also need some attention.

  • 0 in reply to Frank De Stasi
    Prodigy 20 points

    Thank you very much for your help, but there is still a problem!

    At first, as you suggested, I replaced C16 to C20 with 3 x 22uF/35V electrolyte capacitors. Also I changed C4/C_ramp to 1nF.  Replacing R11/R_sense is currently not possible because there is no 3mOhm resistor available.

    Nevertheless when I turn the input on at 48V, the LM5116 breaks.

    If I switch the RFB2/Rfbb resistor back from 33kOhm to 10.7kOhm, everything works fine!

    Is there anything I can do or am I missing anything to get the application running?

    Many thanks in advance,

    Marcel

  • 0 in reply to Marcel Vogelsang
    TI__Expert 8245 points

    Hi,

    Please use 50V rating capacitors for output, and change other components referring to Webench result.