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LMG5200EVM-02: LMG5200EVM-02 GaN Half-Bridge Power Stage EVM in 5Mhz

William Tso
Prodigy 40 points
Part Number: LMG5200EVM-02
Other Parts Discussed in Thread: LMG5200

Dear Master,

I use LMG5200EVM-02 to verify 5Mhz but waveform become very strange and efficiency down to 84%(original all over 92%).

Dut to I need to verify differently inductor,the test circuit will become like that.

5MHz waveform 

  • 0
    TI__Expert 3225 points
    Helli William,

    Thank you for your question and interest on LMG5200. At what condition did you get 92%? And did the efficiency drop to 84% when you added the probe? What is your input/output voltage and power level? The efficiency of LMG5200 EVM depends on its voltage, power level and inductor.

    Thanks and regards,
    Lixing
  • 0
    TI__Intellectual 805 points
    Hello William,
    As Lixing mentioned - what is the condition you got 92% and what is different in the circuit when you get 84% efficiency? Is the inductor different? After switching happens, you have a large ringing on the switch node. You can also see the ringing current on the inductor waveform. This mainly happens due to the parasitic cap on the switch node. I recommend you to check your inductor's parasitic capacitance.
    Regards,
    Serkan
  • 0 in reply to Serkan Dusmez
    Prodigy 40 points

    Dear Serka,

    Indeed I have changed inductor I think maybe it is inductor's problem><

    I will try again.

    Thanks