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Original question:

LMG3410: Voltage at RDRV Pin

LMG3410: Voltage at RDRV Pin

Ryan Vasquez
Prodigy 20 points

Part Number: LMG3410

https://e2e.ti.com/support/power_management/gallium_nitride_solutions/f/1001/t/675922

What is the electrical function of the RDRV pin? Does the current for the GAN gate drive actually flow through the RDRV pin and resistor, or is it just a current mirror? I am also looking to implement a digitally controlled variable rise solution. 

  • 0
    TI__Intellectual 805 points
    Hello Ryan,

    The current going through the RDRV resistor sets the gate current with a current mirror. You can change this value dynamically with a small FET and a resistor. In our HB EVM board, we use a slower dv/dt for low side GAN till the high side GANis fully biased and FAULT is cleared. After FAULT is cleared, we change the low side GAN's dv/dt to 100V/ns. You can see the schematics in the link below (page 8).
    www.ti.com/.../snou140
    Even though we have not tested a digital potentiometer implementation, I see no problem as long as the potentiometer is a ladder type with passive resistors. If it works like a current source, the closed loop frequency would become important.

    Hope it helps.
    Regards,
    Serkan