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UCC23313-Q1: Short Circuit Clamping

Part Number: UCC23313-Q1

Hi Team,

This part has “Short Circuit Clamping” as one in protection functions.

There is the following descriptions about the “Short Circuit Clamping” at section 8.3.4.3 on datasheet.

However, I am not sure about the situation that this clamping operates and why it leads to the protection of IGBT or MOSFET gate.

 Please tell me more detailed situations that this protection is needed.

  • What kind of situation does “short-circuit conditions” explain?
  • If IC doesn’t have this function, what happens?

 ========================================================================================================================   8.3.4.3 Short-Circuit Clamping

The short-circuit clamping function is used to clamp voltages at the driver output and pull the output pin VOUT slightly higher than the VCC voltage during short-circuit conditions. The short-circuit clamping function helps protect the IGBT or MOSFET gate from overvoltage breakdown or degradation. The short-circuit clamping function is implemented by adding a diode connection between the dedicated pins and the VCC pin inside the driver. The internal diodes can conduct up to 500-mA current for a duration of 10 µs and a continuous current of 20 mA. Use external Schottky diodes to improve current conduction capability as needed.

==========================================================================================================================

 Regards,

H.Someno

  • Hi, Someno-san!!!!!

    If a short-circuit happens at the drain of the MOSFET (or IGBT or SiCFET), the VDS will rise quickly. This rise can be applied to the Gate of the device, and it could cause the voltage gate-to-source to rise beyond the specification of the MOSFET, thereby damaging the MOSFET's gate structure.

    So, to prevent this, we have an internal diode from output to the power supply rail which will clamp the output in to the rail voltage, preventing this miller current from causing the gate-to-source voltage from rising and damaging the gate oxide of the MOSFET.

    If we didn't have this diode inside, the output could be pulled above the supply rail, potentially damaging the MOSFET's gate oxide. 

    Let me know if you have further questions, Someno-san, and if not, please mark this thread Resolved by pressing the green button.

    Best regards,

    Don