The VDD bypass capacitor provides the gate charge for the low-side and high-side transistors and to absorb the reverse recovery charge of the bootstrap diode. The required bypass capacitance can be calculated with Equation 1.

Equation 1.

where

• Q_gH and Q_gL are gate charge of the high-side and low-side transistors, respectively
• Q_rr is the reverse recovery charge of the bootstrap diode, which is typically around 4nC
• ΔV is the maximum allowable voltage drop across the bypass capacitor

TI recommends a 0.1–µF or larger value, good-quality ceramic capacitor. The bypass capacitor must be placed as close as possible to the device pins to minimize the parasitic inductance.