Patent ID: 9667155
Date: 2017-05-30
CPC Classifications: H02M

Claim:
1. A switching power supply, comprising: a transformer having a primary coil and a secondary coil; a switching element that is connected in series to the primary coil of the transformer so as to turn a direct-current input voltage applied to the primary coil of the transformer ON and OFF; a rectifying and smoothing circuit that rectifies a voltage induced in the secondary coil of the transformer to generate a direct-current output voltage; and a control circuit that turns the switching element ON and OFF in accordance with the direct-current output voltage, wherein the control circuit includes an input correction circuit that detects a switching period of the switching element and limits a peak value of a current flowing through the switching element in accordance with the detected switching period, and wherein the input correction circuit includes: a period detection circuit that detects the switching period T of the switching element; a calculation circuit that calculates a control value T