5 Design Consideration on RBOOT

The RBOOT pin is in series with the CBOOT capacitor, which not only limits the HS driving current, but also impacts the voltage presented on BT-SW pin during the discharging and refresh period. The voltage between the BOOT to SW pins serves as the bias power supply for the HS driver, the level-shift circuitry that transmits control information between the controller and HS gate driver. It must be noted that adding a resistor in series with the bootstrap capacitor can introduce circuit effects beyond slowing the high-side MOSFET transition time.