Abstract: An undervoltage protection circuit and an overvoltage protection circuit include a first comparator and a second comparator. The first comparator has a first input terminal, a second input terminal, and a first output terminal. The second comparator has a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal receives a reference voltage and the fourth input terminal receives a first feedback voltage. The first and the second output terminals are coupled with a logic device. The first feedback voltage is converted to a second feedback voltage by the delay circuit and the voltage level shifter. The first comparator outputs a detection enabling voltage for undervoltage/overvoltage detection when the first feedback voltage crosses the second feedback voltage. The logic device outputs a protection voltage level undervoltage/overvoltage protection when the first feedback voltage crosses the reference voltage.

Abstract: An undervoltage protection circuit and an overvoltage protection circuit include a first comparator and a second comparator. The first comparator has a first input terminal, a second input terminal, and a first output terminal. The second comparator has a third input terminal, a fourth input terminal, and a second output terminal. The third input terminal receives a reference voltage and the fourth input terminal receives a first feedback voltage. The first and the second output terminals are coupled with a logic device. The first feedback voltage is converted to a second feedback voltage by the delay circuit and the voltage level shifter. The first comparator outputs a detection enabling voltage for undervoltage/overvoltage detection when the first feedback voltage crosses the second feedback voltage. The logic device outputs a protection voltage level undervoltage/overvoltage protection when the first feedback voltage crosses the reference voltage.

Abstract: A soft switch driving circuit is disclosed for a DC converter, to transform an input voltage into an output voltage. The soft switch driving circuit includes a regulating module for outputting a reference voltage, a first bootstrap circuit for generating a first voltage value according to a DC voltage, a second bootstrap circuit for generating a second voltage value according to the reference voltage, a control module for generating a plurality of control signals according to a control voltage, a switch module having one end coupled to the first bootstrap circuit and another end coupled to the second bootstrap circuit for outputting a voltage signal, and an output circuit connected to the control module and the switch module for transforming the input voltage into the output voltage according to the voltage signal and one of the plurality of controlling signals.

Abstract: A method for reducing energy loss in a DC-DC converter comprises detecting an output current of the DC-DC converter to generate a sensing signal, adjusting a frequency of an oscillation signal, comparing a reference signal and a feedback signal of the DC-DC converter to generate a comparison result, comparing the comparison result and the oscillation signal to generate a PWM signal, and determining whether an input end of the DC-DC converter is electrically connected to an output end of the DC-DC converter according to the PWM signal.