Question about the meaning of "±20V" specification for Vge on IGBT datasheet

[jhorneljohn02]

Hi guys I am really confused what is the meaning of the "±20V" for the Vge of an IGBT written on it's datasheet. I have searched everywhere on the internet but have not found any explanation.

So my question is, does it mean that the driving square wave voltage I can use is +20V to charge the gate capacitor and -20V to discharge it so it is a total of 40V peak to peak max?

Hoping for everyone's kind consideration.

All the best,
Jhornel

[davekni]

Yes, I think you understand correctly.  The gate-to-emitter voltage can range from +20V to -20V.  Tesla-coil builders often exceed those ratings. Unlike a power supply or motor driver, Tesla coils don't need to run reliably for 24 hours a day for years.

[jhorneljohn02]

Thank you so much for your response, davekni! I guess for example I can use a 20v zener back to back connected to the gate and emitter to limit the gdt voltage output to 40 Volts peak to peak right?

[davekni]

Yes, back-to-back zener diodes are common for gate protection.  A few FETs have such built into the part.  TVS diodes are also common.  TVS diodes are just zener diodes designed specifically for clamping high peak currents.  Bidirectional TVS diodes have two zeners back-to-back internally.  The down-side of TVS diodes is higher capacitance.  For smaller IGBTs or FETs, that capacitance can add significantly to required gate-drive current.

[jhorneljohn02]

Thank you so much. Now I understand. And I also learned additional info about TVS diodes having larger capacitance. Thank you!

[Mads Barnkob]

Hi guys I am really confused what is the meaning of the "±20V" for the Vge of an IGBT written on it's datasheet. I have searched everywhere on the internet but have not found any explanation.

So my question is, does it mean that the driving square wave voltage I can use is +20V to charge the gate capacitor and -20V to discharge it so it is a total of 40V peak to peak max?

Hoping for everyone's kind consideration.

All the best,
Jhornel

I explain how to read some of the most important IGBT datasheet figures in my Tesla Coil IGBT selection part of the DRSSTC design guide.

The breakdown voltage is as high as 80VDC, but the low voltage is to prevent electron/hole flow/injection going nuts and by limiting the gate voltage you can limit the C-E current. More details in the article