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LM5116 Design problems

user4800525
Other Parts Discussed in Thread: LM5116

Hi guys.I meet with some questions and look forward to your replying.Pls kindly find more details below.

Here is my schematic and  shaping of  the inductance

input 31.5V . I  need 11V output

No-load.

Output waveform is triangular wave.Output meets disign requirement.But I  do not know why I cannot test the drive voltoge of MOSFETS?

Light load

When I add a 50ohm resistor to the  output.Lm5116 chip damage  in a short time.I don't understand what caused it?

Very appreciate if you can reply .

  • 0
    TI__Guru**** 191445 points
    I'm not an expert on LM5116, but I am not seeing any input capacitance across the high and low side switches. There is also very little output filter capacitance. You might start there.
  • 0
    TI__Intellectual 1745 points
    I will contact an engineer more familiar with the part, but in the mean time, can you provide some more information.

    What load currents are you trying to achieve? When you say you add a 50ohm resistor to the output, are you saying 50ohm to ground on Vout? How long is "short time"? 1 second, 1 minute, 10 minutes?
  • 0
    TI__Mastermind 21720 points
    John is right, there needs to be more input and output capacitance.

    Can you provide any waveforms for "normal" operation and after the IC is damaged? Is the LM5116 still switching? What is the VCC voltage? Observations like this will help to narrow down the cause of the problem.

    Thanks,

    Garrett