Patent ID: 8106628

Claim:
A control circuit of a capacitor charging apparatus, the capacitor charging apparatus including a transformer and an output capacitor charged with current flowing through a secondary coil of the transformer, which charges the output capacitor by performing a switching control of a switching transistor provided on a path leading to a primary coil of the transformer, the control circuit comprising: a primary-current detection circuit which detects a primary current flowing through the primary coil of the transformer; and a switching control unit which monitors at least the primary current detected by said primary-current detection circuit and outputs to a control terminal of the switching transistor a switching signal for specifying ON to the switching transistor until the primary current reaches a predetermined peak current value and then specifying OFF to the switching transistor during an off-time, wherein said switching control unit adjusts the switching signal outputted to the control terminal of the switching transistor, according to the predetermined peak current value, wherein the switching transistor is a bipolar transistor, and wherein said switching control unit adjusts a current value of a base current, which is supplied to a base of the bipolar transistor as the switching signal, in accordance with the predetermined peak current value.