7.3.8 N-Channel Buck Switch and Driver

The LM5160 integrates an N-channel buck switch and associated floating high-side gate driver. The gate driver circuit works in conjunction with an external bootstrap capacitor and an internal high voltage bootstrap diode. A 10-nF or larger ceramic capacitor connected between BST and SW provides the voltage to the high-side driver during the buck switch on-time. During the off-time, the SW node is pulled down to approximately 0 V and the bootstrap capacitor charges from VCC through the internal bootstrap diode. The minimum off-time of 170 ns (typical) provides a minimum time each cycle to recharge the bootstrap capacitor.