Patent ID: 8018255

Claim:
A non-insulated DC-DC converter comprising: a choke coil; an output capacitor connected between one end of the choke coil and a negative terminal of a DC input power source; a high side MOSFET whose drain terminal is connected to a positive terminal of the DC input power source and whose source terminal is connected to the other end of the choke coil; a low side MOSFET whose drain terminal is connected to the other end of the choke coil and whose source terminal is connected to the negative terminal of the DC input power source; and a gate driver controlled in accordance with a pulse signal and alternately driving the high side MOSFET and the low side MOSFET, wherein a part of the gate driver, the part driving the low side MOSFET, includes: a gate driving DC power source whose negative terminal is connected to the source terminal of the low side MOSFET; a capacitor for generating negative voltage; a first switching element connected between a positive terminal of the gate driving DC power source and a gate terminal of the low side MOSFET; a second switching element connected between the positive terminal of the gate driving DC power source and one end of the capacitor for generating negative voltage; a third switching element connected between the gate terminal of the low side MOSFET and the other end of the capacitor for generating negative voltage; a fourth switching element connected between the one end of the capacitor for generating negative voltage and the source terminal of the low side MOSFET; and a fifth switching element connected between the other end of the capacitor for generating negative voltage and the source terminal of the low side MOSFET.