| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive boot-strap type switching power supply circuit which stably performs power feeding to a circuit for driving a switching element even at light loading. SOLUTION: The switching power supply circuit comprises: the switching element 1; a boot strap circuit having a boot-strapping capacitor C1 connected to a source of the switching element 1 at its one end; the drive circuit 4 which generates a drive signal fed to a gate of the switching element by using a boot strap voltage V<SB>B</SB>outputted from the boot strap circuit; a voltage controlling DMOS 5 arranged between the source of the switching element 1 and the ground; and a current limit part (including a voltage detecting DMOS 6, a voltage detecting NMOS 7, a voltage detecting resistor 8, a comparator 11, and a DMOS driver 9) for limiting a current flowing in the voltage controlling DMOS 5. COPYRIGHT: (C)2009,JPO&INPIT
|
