Patent ID: 7498784

Claim:
An average current detector circuit for outputting a voltage corresponding to an average value of a current flowing through a coil during a period in which a pulse, which repetitively becomes ON and OFF, is being ON, said circuit comprising: a voltage circuit which outputs a voltage corresponding to an instantaneous value of the current flowing through said coil; a first sample/hold circuit which holds the voltage from said voltage circuit, by entering a hold state from a sampling state, at a timing at which the pulse becomes ON; a first dividing circuit which outputs a voltage corresponding to ½ of a difference between the voltage held in said first sample/hold circuit and the voltage output from said voltage circuit; and a second sample/hold circuit which holds the voltage output from said first dividing circuit, by entering a hold state from a sampling state, at a timing at which the pulse becomes OFF, and outputs the held voltage corresponding to a sum of the held voltage in the first sample/hold circuit and the held voltage in the second sample/hold circuit as a voltage corresponding to an average value of the current flowing through said coil, during a period in which the pulse is becoming ON.