The LM516x 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 high-quality ceramic capacitor connected between the BST and SW pins provides the voltage to the high-side driver during the buck switch on time. See Section 8.3.2 for limitations. During the off time, the SW pin is pulled down to approximately 0 V, and the bootstrap capacitor charges from the internal VCC through the internal bootstrap diode. The minimum off-timer, set to 50 ns (typical), ensures a minimum time each cycle to recharge the bootstrap capacitor. When the on time is less than 300 ns, the minimum off-timer is forced to 250 ns to ensure that the BST capacitor is charged in a single cycle. This is vital during wakeup from sleep mode when the BST capacitor is most likely discharged.