Texas Instruments Incorporated
BOOTSTRAP CAPACITOR REFRESHING FOR INVERTING BUCK-BOOST DC-DC CONVERTERS

Abstract:

A converter having an input adapted to be connected to an input voltage and an output adapted to supply an output voltage, the converter comprising: a high-side switch having a first current terminal, a second current terminal and a first control terminal, the first current terminal is coupled to the input voltage and the second current terminal is coupled to a switching node; a high-side driver circuit having an input, a first supply input, a second supply input and an output coupled to the first control terminal, the second supply input is coupled to the switching node; a bootstrap capacitor having a first terminal and a second terminal, the first terminal coupled to the first supply input and the second terminal coupled to the second supply input; a switch having a first terminal and a second terminal, the first terminal of the switch is coupled to the first terminal of the bootstrap capacitor and the second terminal of the switch is connected to a supply voltage (V.sub.DD volts above ground).