BUCK SWITCHING REGULATOR

摘要

The present invention discloses a buck switching regulator including a power stage, a driver circuit and a bootstrap capacitor. The power stage includes an upper-gate switch, a lower-gate switch and an inductor. The upper-gate switch is electrically connected between an input terminal and a switching node. The lower-gate switch is electrically connected between the switching node and ground. The bootstrap capacitor is electrically connected between a boost node and the switching node, wherein the boost node is electrically connected to a voltage supply. When a voltage across the bootstrap capacitor is smaller than a reference voltage, the lower-gate switch is turned on to charge the bootstrap capacitor from the voltage supply. When the charging operation to the bootstrap capacitor has been conducted over a predetermined time period or when the current of the inductor has reached a predetermined value, the charging operation to the bootstrap capacitor is ceased.

主权项

1. 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 lower-gate switch having one end electrically connected to the switching node and another end electrically connected to ground; andan inductor having one end electrically connected to the switching node and another end electrically connected to the output terminal; a bootstrap capacitor, which is electrically connected between a boost node and the switching node, wherein the boost node is electrically connected to a voltage supply; and a driver circuit for controlling the operation of the upper-gate switch and the lower-gate switch, the driver circuit including: a control signal generation circuit for generating a control signal to determine ON-time of the upper-gate switch and ON-time of the lower-gate switch; and a bootstrap capacitor charging control circuit coupled to the control signal generation circuit, for determining whether a voltage across the bootstrap capacitor is smaller than a reference voltage and generating an output signal accordingly, wherein when the voltage across the bootstrap capacitor is smaller than the reference voltage, the control signal generation circuit turns ON the lower-gate switch to charge the bootstrap capacitor from the voltage supply according to the output signal from the bootstrap capacitor charging control circuit.