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.

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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: