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UCC25660EVM-064: What do we need to adjust if we want to use LMG2650 as power switch?

Jass Jin
Intellectual 2465 points

Part Number: UCC25660EVM-064

Tool/software:

Hi expert,

My customer wants to follow EVM's design, but change MOSFET to LMG2650 and run at over 500kHz frequency.

LMG2650 has internal gate driver, can we connect VCC to HS, HB to GND to only give control signal to power stage?

What else do we need to adjust the EVM's design?

If my customer wants to increase input voltage to 450V to test EVM? 

I think input capacitor need to change for higher voltage version, what else do we need to adjust in EVM?

Thanks!

  • 0
    TI__Guru* 85926 points

    Hello,

    Your inquiry is under review and I will get back to you shortly.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru* 85926 points

    Hello,

    Please see my comments below.

    My customer wants to follow EVM's design, but change MOSFET to LMG2650 and run at over 500kHz frequency.

    > The EVM was design to run at a resonant frequency of 100 kHz.

    > The UCC25660x devices have a maximum frequency of  750 kHz. To ensure you have enough control bandwidth, I would recommend designing to a resonant frequency of 250 kHz or less.

    > If your input range is limited you could go as high as 500 kHz on the resonant frequency.

    LMG2650 has internal gate driver, can we connect VCC to HS, HB to GND to only give control signal to power stage?

    >You also may need to resized the VCC and boot capacitors based on the LMG2650's gate capacitances.

    >CBoot = 10*Cg

    > CVCC = 10*Cboot 

    What else do we need to adjust the EVM's design?

    > It you do a a 500 kHz design you will need to change the magnetics and reevaluate heat sinking of the semiconductors.

    >You also may need to resized the VCC and boot capacitors based on the LMG2650's gate capacitances.

    If my customer wants to increase input voltage to 450V to test EVM? 

    >If your design needs a high input voltage range your components are going to need to be resized the higher voltages both on the primary and secondary.

     

    I think input capacitor need to change for higher voltage version, what else do we need to adjust in EVM?

    >You are correct that if you are going to run at a higher input voltage that the input capacitor's voltage range may need to be increased.

    I discussed this question with an internal applications engineer and systems engineer.  He mentioned that he is supporting you directly, so I will close this issue.

    Regards,