8.2.2.1 VDD Bypass Capacitor

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.

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 4 nC. ΔV is the maximum allowable voltage drop across the bypass capacitor. A 0.1-µF or larger value, good-quality, ceramic capacitor is recommended. The bypass capacitor should be placed as close to the pins of the IC as possible to minimize the parasitic inductance.