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Bootstrap Capacitor Calculator
Estimate minimum bootstrap capacitance and peak bootstrap-diode current for a high-side gate driver, using the gate-charge and charge-balance methods from typical bootstrap driver design guides.
Sliders map directly to the variables in the formulas below — adjust them to match your driver's datasheet values.
Gate capacitance estimate
3.30 nF
Cg = Qg / (VDD − VD)
10× gate cap guideline
33.00 nF
Cboot ≥ 10 × Cg
Detailed minimum Cboot
56.72 nF
Cboot ≥ Qtotal / ΔVHB
Peak diode current
50.0 mA
Ipeak = Cboot × dV/dt
Bootstrap voltage margin
2.50 V
ΔVHB = VDD − VD − VHBL
Cg = Qg / (VDD − VD)
Cboot ≥ 10 × Cg
Qtotal = Qg + IHBS × Dmax / fsw + IHB / fsw
ΔVHB = VDD − VD − VHBL
Cboot ≥ Qtotal / ΔVHB
Ipeak = Cboot × dV/dt
References
- Texas Instruments SLUA887A — Bootstrap Circuitry Selection for Half-Bridge Configurations
- STMicroelectronics AN5789 — Considerations on Bootstrap Circuitry for Gate Drivers