Patent ID: 8502511

Claim:
A buck switching regulator for converting an input voltage supplied from an input terminal to an output voltage at an output terminal, comprising: a power stage, including: an upper-gate switch having one end electrically connected to the input terminal and another end electrically connected to a switching node; a first lower-gate switch having one end electrically connected to the switching node and another end electrically connected to a first node, wherein the first node is electrically connected to ground; a second lower-gate switch having one end electrically connected to the switching node and another end electrically connected to the first node; and an inductor having one end electrically connected to the switching node and another end electrically connected to the output terminal; a driver circuit for controlling the operation of the upper-gate switch and the first lower-gate switch; and a bootstrap capacitor, which is electrically connected between a boot node and the switching node, wherein the boot node is electrically connected to a supply voltage; wherein when a voltage across the bootstrap capacitor is smaller than a reference voltage, the second lower-gate switch is turned on to charge the bootstrap capacitor from the supply voltage.