UCC21759-Q1: Bootstrap configuration

Johnson,

Johnson John said:

Can you please confirm wheher this device will work in Bootstrap Highside configuration? Our circuit requirement is, IGBT full bridge driver ( 6 phase) and want to use single VDD (15V) supply for driver for all the 6 IGBTs.

This part can work with a bootstrap highside supply, but as the device is capable of much higher current than halfbridge drivers, a larger bootstrap Cap than HB-iso drivers will be required which will therefore have larger peak currents, especially if . The same design process & guidance as for our isolated half-bridge drivers applies here equally, I'm linking some resources which will help:

1)Design /guide from UCC21520 datasheet https://www.ti.com/lit/ds/symlink/ucc21520.pdf#page=28.

I highly recommend to utilize item 1 and if possible, test in pspice

2) Our appnote on bootstrap circuit https://www.ti.com/lit/an/slua887/slua887.pdf

3) Bootstrap calculator https://www.ti.com/lit/zip/sluraz5

Keep in mind there are many tradeoffs with bootstrap opposed to

A push-pull converter like SN6505B is also a very good low-cost (though not as low-cost as a bootstrap), small footprint solution which will far exceed the performance of a bootstrap and can also directly generate both +ve & -ve bias supply directly based on transformer winding, example here;

If this answers your question, please let me know by pressing the green button.

best

Dimitri