Patent ID: 7145316
Filing Date: 2006-12-05
Classification: H02M

Abstract:
1. A control circuit in a switching regulator receiving an input voltage and providing a regulated output voltage having a substantially constant magnitude, the switching regulator including a high-side power switch and a low-side power switch connected in series between the input voltage and a first power supply voltage, the high-side power switch and the low side power switch being turned on alternately to generate a switching output voltage at a common node between the power switches which switching output voltage is used to generate the regulated output voltage, the high-side power switch being driven by a high-side driver circuit and the low-side power switch being driven by a low-side driver circuit where the high-side driver circuit is supplied by a bootstrap voltage and the switching output voltage, the control circuit comprising: a voltage feedback and divider circuit coupled to receive the bootstrap voltage and divide the bootstrap voltage to generate a monitor voltage; a comparator circuit having a first input terminal coupled to receive the monitor voltage and a second input terminal coupled to receive a voltage indicative of the switching output voltage, the comparator circuit generating an output signal at an output terminal, the output signal having a first state when the monitor voltage is equal to or less than the voltage indicative of the switching output voltage; and a logic circuit coupled to receive the output signal of the comparator circuit and generate a high-side drive control signal to the high-side driver circuit and a low-side drive control signal to the low-side driver circuit, wherein the logic circuit generates the high-side and low-side drive control signals in response to the output signal of the comparator circuit having the first state to cause the high-side power switch to turn off and the low-side power switch to turn on, thereby recharging the bootstrap voltage to a first voltage.