The bootstrap power supply is one of the most widely used methods to supply power to the high-side drive circuitry of a gate driver IC. It consists of a bootstrap diode and a bootstrap capacitor as shown in the following figure.

Click image for larger version

Name:	bootstrap.PNG
Views:	2
Size:	23.2 KB
ID:	3202


This method has the advantage of being both simple and low-cost. However, the requirement to refresh the charge on the bootstrap capacitor may result in limitations on the power converter’s duty-cycle and power switch’s on-time. Proper capacitor and bootstrap resistance selection can drastically reduce these limitations. For more information, please refer to the following two application notes:
https://www.infineon.com/dgdl/Infine...585242c11947b1
https://www.infineon.com/dgdl/an-978...53559f7cf21200