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1. A bootstrap refresh control circuit for a voltage converter, wherein the voltage converter comprises a high side switch, a low side switch and a bootstrap capacitor for providing a bootstrap voltage signal to supply a high side driver of the high side switch, and wherein the voltage converter is configured to receive an input voltage at an input terminal and to provide an output voltage at an output terminal based on driving the high side switch and the low side switch to switch on and off, and wherein the bootstrap refresh control circuit comprising:
a bootstrap refresh module, wherein the bootstrap refresh module comprises a first comparing module having a first input terminal, a second input terminal and an output terminal, and wherein the first input terminal of the first comparing module is configured to receive the bootstrap voltage signal, the second input terminal of the first comparing module is configured to receive a bootstrap refresh threshold, and the first comparing module is configured to compare the bootstrap voltage signal with the bootstrap refresh threshold to provide a first comparing signal having a first logic state and a second logic state at the output terminal, and wherein the first comparing signal has the first logic state when the bootstrap voltage signal is lower than the bootstrap refresh threshold, and wherein the first comparing signal has the second logic state when the bootstrap voltage signal is larger than the bootstrap refresh threshold; and a voltage difference module having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal of the voltage difference module is configured to receive a feedback signal representing the output voltage of the voltage converter, the second input terminal of the voltage difference module is configured to receive a reference voltage signal representing a desired value of the output voltage of the voltage converter, the voltage difference module is configured to compare the feedback signal with the reference voltage signal so as to provide a difference signal at the output terminal; and wherein
when the first comparing signal has the first logic state, the bootstrap refresh module is configured to decrease the output voltage of the voltage converter; and wherein when the feedback signal is smaller than the reference voltage signal, the bootstrap refresh control circuit is configured to control the high side switch and the low side switch to switch on and off based on the difference signal so as to charge the bootstrap capacitor for refreshing the bootstrap voltage signal. |
