Turn off PNP for gate drive with charge-pump high side driver IC?

[grizedale]

Hi,

Do i need to add local PNP turn off circuits to the FETs of my full-bridge? (90-265VAC, 330W output)

the FETs are all driven by a NCP5181 bootstrap hi-and-lo side driver IC.

NCP5181:
https://www.onsemi.com/pub_link/Collateral/NCP5181-D.PDF

I mean a local PNP turn off circuit as in fig13, page 14 of this.....

Local PNP turn-off circuit:-
**broken link removed**


...its just that i believe that the turning on of the low side fet in an arm, spuriously turns on the high side fet in the same arm, resulting in shoot-through current for a short interval.
-the PNP circuit would prevent this?

 

[mtwieg]

I've seen such gate drive circuits used when driving relatively large IGBTs over long leads (like over a foot of twisted pair). That's generally because of the problem you're referring to, with parasitic turn on of devices (which can happen to both low and high side switches). But if your driver circuit has a low impedance connection to the gate and source of each device, then I doubt it is really necessary, and the pnp won't make the turn on any faster (unless you're working with very large IGBTs or FETs).