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LMG2100R044: Slew rate control

Shyama Agrawal
Prodigy 130 points
Part Number: LMG2100R044

Tool/software:

Hi,

As per below image, Rvcc is relevant for buck converter. I agree that Rvcc will impact turn ON of low side GaN FET and Rbst will impact turn ON of high side GaN FET but how can we say Rvcc is more critical for buck converter given generally in Si FET based buck converter slower turn ON of high side FET actually helps control Vds spike of low side FET due to reverse recovery of body diode of Low side FET.

We are working on a buck converter with LMG2100R044, can you recommend if we should use Rvcc or Rbst?

  • +1
    TI__Intellectual 1170 points

    Hi Shyama,

    Yes, you are correct. For buck, the high side FET is hard switched, hence to control the Vds spike we need to control the turn on of high side FET (using Rbst).
    For buck, the recommended Rbst is between 0ohm to 6ohm. With higher resistance, the spikes are reduced but, due to slow turn on, switching losses will increase.
    Hence, we need to find a balance between tolerable Vds peak and efficiency. Please try different values between 0-6 ohm.
    Rvcc will not matter in case of buck (anything between 0-6 ohm is okay).

    Will are going to correct the datasheet soon. Thank you for pointing out.


    Best Regards,
    Madhur