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Original question:

UCC21750: DRIVER UCC21750 WITH CLAMP PIN

UCC21750: UCC21750 -active clamp

han zheng
Prodigy 30 points
Part Number: UCC21750

Tool/software:

Hi, I am planning to use UCC21750 as a driver chip, I expect to add TVS between CG to realize active clamp function to avoid VCE too high to damage IGBT, is there any recommended circuit?

  • 0
    TI__Mastermind 23206 points

    Hi Han,

    IGBT's usually already switch slow enough to avoid VCE overshoot. This circuit is more commonly needed for faster switching devices like MOSFETs and SiC FETs.

    This circuit relies on a Zener diode between collector and gate. It will be hard to find a Zener TVS diode with a voltage rating as high as the IGBT it is trying to protect. This will prevent you from using the full high-voltage range of the IGBT. You might be able to use an SCR instead if the goal is to drain all the power to 0V in the case of an over-voltage.

    I do not recommend this TVS circuit placement for normal TVS protection of MOSFETs, as protection still relies on turning the FET ON, which will add propagation delay to the protection, and inefficiency when turning the FET back off. Instead, a TVS diode directly in parallel to the switch will provide the fastest clamping of transient voltage and minimal shoot through for normal operation.

    The Vge TVS diode protecting the gate is a good addition, as 12-20V is a very easy to find Zener voltage range.

    Best regards,

    Sean