Patent ID: 8194420

Claim:
A method of generating a signal representative of a current delivered by a primary-sensing flyback switching regulator, having a primary side generating a primary voltage magnetically coupled to a secondary side that generates a regulated output voltage on output terminals of the regulator, the primary side including a feedback control circuit that generates a feedback voltage representative of said output voltage, a logic flag for flagging demagnetization phases of said switching regulator and a control voltage that fixes a maximum current level that may circulate in the primary side of the regulator in function of a difference between a reference voltage and said feedback voltage, the method using only signals available at the primary side and comprising: discharging a filter capacitor during demagnetization phases through a resistor and charging it with a constant current during the remaining part of switching periods flagged by said logic flag; generating said representative signal as a voltage proportional to a ratio between said control voltage and a charge voltage of said filter capacitor.