GATE DRIVE CIRCUIT OF SWITCHING CIRCUIT, AND CONTROL CIRCUIT OF SWITCHING POWER SUPPLY

摘要

According to the present invention, a switching circuit 100 includes a high-side transistor MH and a low-side transistor ML of N channels. A switch SW1 and a rectifying element D1 of a PMOS transistor are provided in series between a constant voltage line through which a constant voltage V_REG is supplied and a bootstrap line VB. A comparison circuit 210 operates by taking the high-side power supply voltage V_BS as a power supply, the high-side power supply voltage being the voltage difference between the bootstrap line VB and a switching line VS, and generates a detection signal OVDET that indicates a magnitude relationship between the high-side power supply voltage V_BS and a threshold voltage V_TH. A level shift circuit 220 level-shifts the detection signal OVDET down to a signal of which the ground voltage is low. A PMOS driver 212 drives the switch SW1 asynchronously with switching of the low-side transistor ML in response to an output of the level shift circuit 220.