Patent ID: 9312773
Filing Date: 2016-04-12
CPC Classification: H02M,H03K,Y02B

Claim Text:
1. A bootstrap refresh control circuit for a power converter, wherein the power converter comprises a high side switch, a low side switch and a bootstrap capacitor for providing a bootstrap voltage to supply a high side driver of the high side switch, and wherein the power converter is configured to receive an input voltage and to provide an output voltage and an output current based on driving the high side switch and the low side switch to switch on and off, the bootstrap refresh control circuit comprising: a first comparison module having a first comparing input terminal, a second comparing input terminal and a first comparing output terminal, wherein the first comparing input terminal is configured to receive the bootstrap voltage, the second comparing input terminal is configured to receive a first threshold signal, and the first comparison module is configured to compare the bootstrap voltage with the first threshold signal to provide a bootstrap refresh signal at the first comparing output terminal; and a control module having a first control input terminal configured to receive the bootstrap refresh signal, wherein the control module is configured to regulate the on and off switching of the high side switch and the low side switch at least partially based on the bootstrap refresh signal so as to control charging of the bootstrap capacitor, and wherein the control module is configured to regulate the high side switch and the low side switch to switch on and off in complementary with a substantially constant frequency when the bootstrap voltage is lower than the first threshold signal further wherein the bootstrap refresh signal has a first logic state when the bootstrap voltage is lower than the first threshold signal and has a second logic state when the bootstrap voltage is higher than the first threshold signal; and wherein the control module further has a second control input terminal configured to sense the output voltage, and a third control input terminal configured to sense the output current; and wherein the control module is configured to regulate the high side switch and the low side switch to switch on and off in complementary with the substantially constant frequency in response to the first logic state of the bootstrap refresh signal, and is configured to regulate the high side switch and the low side switch to switch on and off according to the output voltage and the output current in response to the second logic state of the bootstrap refresh signal.