Patent ID: 8264807

Claim:
A start-up in-rush current protection circuit for a DCDC converter with an output stage circuit having a power transistor, an inductor and a smoothing capacitor connected in series between a power supply and a ground, the protection circuit comprising: a coupling capacitor having a first terminal connected to said power supply, a PMOS transistor having a drain terminal connected to a gate terminal of the power transistor, a source terminal connected to the power supply, and a gate terminal connected to the power supply; a first NMOS transistor having a drain terminal connected to a gate terminal of said PMOS transistor, a source terminal connected to ground, and a gate terminal connected to a second terminal of said coupling capacitor; and a driver block having an output terminal connected to said drain terminal of said PMOS transistor, for outputting voltage driving signals to the gate terminal of the DCDC converter power transistor.