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LM51231-Q1: GaNFet usable?

Kristian Villien
Prodigy 10 points
Part Number: LM51231-Q1
Other Parts Discussed in Thread: LM5123-Q1

Hello TI,

I am doing a booster design for a customer using the LM5123-Q1, and I have a couple of questions:


1) In the datasheet, it says: "For stability reasons, the VREF capacitor (CVREF) should be between 330 pF and 1 nF. 470 pF is recommended."
In the application note, on "Figure 1-1. Typical Application", a 470nF capacitor is placed.
Can i assumme that the datasheet is correct?

2) What is your recommendations with regards to added an aditional gate resistor to reduce ringing?

3) Since it is a 5V FET driver, I am planning to design with GaNFETs. GaNFET generally have a gate voltage limit of -4V to 6V, so I do not see any reason why it would not work. What is your opinion?
I am looking at using EPC2067.

  • 0
    TI__Guru 59435 points

    Hello Kristian,

    Thank you for using E2E.

    1) Yes, the datasheet is correct. We need to update the application note.

    2) Please use the same gate resistors for all transistors, do not use a resistor that is bigger than 10 ohm, and if you use a resistor that is bigger than a few ohms, place a diode in parallel to turn off the transistor fast. In general, I recommend using snubbers instead of gate resistors.

    3) Normally this should work, but with GaN, layout is even more important as they can switch very fast.

    Best regards,
    Brigitte