POWER SUPPLY CIRCUIT AND CHARGING DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To prevent a coil and a switching element of a discharge circuit from being burned out due to an excessive discharge current.SOLUTION: A power supply circuit 8 includes a PFC (power factor correction) circuit 3, a capacitor C for smoothing an output voltage of the PFC circuit 3, and a discharge control circuit 4 for controlling discharge of the capacitor C. The discharge control circuit 4 has: a coil L1 (a primary winding of a transformer 13) and a switching element Q2 which are connected in series between output lines 16a and 16b of the PFC circuit 3; and a switching control section 15 for turning on/off the switching element Q2 by a pulse signal. The switching control section 15 gradually discharges the electric charge of the capacitor C through the coil L1 and the switching element Q2 while changing the duty of the pulse signal.