Patent ID: 7109693

Claim:
A semiconductor integrated circuit for a power supply device comprising: a first node to which a first gate control signal for a first switching element is output, the first switching element having a control terminal, a source terminal and a drain terminal, the control terminal being coupled to the first node, and one of the source and the drain terminals being coupled to a first power supply terminal; an inductor which has a first terminal and a second terminal, the first terminal of the inductor being coupled to the other of the source and drain terminals of the first switching element; a first capacitor which has a first terminal to which a load element is to be coupled and a second terminal, the first terminal of the first capacitor being coupled to the second terminal of the inductor, the second terminal of the first capacitor being coupled to a second power supply terminal; a first resistor which has a first terminal and a second terminal, the first terminal of the first resistor being coupled to the other of the source and the drain terminals of the first switching element; a second capacitor which has a first terminal and a second terminal, the first terminal of the second capacitor being coupled to the second terminal of the first resistor, the second terminal of the second capacitor being coupled to the second terminal of the inductor; a second node to which a second gate control signal for a second switching element is output, the second switching element having a control terminal, a source terminal and a drain terminal, the control terminal of the second switching element being coupled to the second node, one of the source and drain terminals of the second switching element being coupled to the other of the source and drain terminals of the first switching element, and the other of the source and drain terminals of the second switching element being coupled to the second power supply terminal; and a hysteresis comparator, which has an input terminal coupled to the second terminal of the first resistor and an output terminal, and which compares a first voltage received from the input terminal thereof with a first and a second threshold voltage relating to a hysteresis characteristic thereof and provides a discrimination result for first and the second nodes.