What Are Bootstrap Capacitors?

Power electronics play a critical role in converting and managing electrical energy efficiently. As electric vehicles (EVs), renewable energy systems, and consumer electronics quickly become more powerful, the demand for high-voltage power electronics is quickly increasing. This means the importance of components like bootstrap capacitors has grown significantly.

In power electronics, a bootstrap capacitor is a specific type of capacitor used to drive high-side MOSFETs efficiently. The bootstrap capacitor plays a critical role in maintaining the gate voltage required to turn on the high-side MOSFET in a half-bridge or full-bridge configuration. By using the charge stored in the bootstrap capacitor, the high-side MOSFET's gate voltage can be boosted above the supply voltage, ensuring proper switching operation and enabling efficient power conversion (Figure 1).