Patent ID: 8742691

Claim:
A load driving circuit configured to convert an input voltage into a driving signal, and to supply the driving signal thus converted to a load, the load driving circuit comprising: a main transformer arranged such that the load is connected to a secondary winding side thereof; a first error amplifier configured to generate a feedback signal that corresponds to the difference between a detection signal which indicates an electrical state of the load and a predetermined first reference voltage; a current generating transistor; a current generating resistor arranged between the current generating transistor and a fixed voltage terminal; a second error amplifier arranged such that a first input terminal thereof receives, as an input signal, an electric potential at a connection node that connects the current generating transistor and the current generating resistor, a predetermined second reference voltage is input to a second input terminal thereof, and an output terminal thereof is connected to a control terminal of the current generating transistor; an adjustment resistor arranged between an output terminal of the first error amplifier and a connection node that connects the current generating transistor and the current generating resistor; an oscillator configured to alternately repeat a state in which a capacitor is charged using a charging current that corresponds to a frequency control current that flows through the current generating transistor and a state in which the capacitor is discharged, so as to output a pulse frequency modulation signal having an edge synchronized to the charge/discharge transition; and a main transformer driving unit configured to drive a primary winding of the main transformer according to the pulse frequency modulation signal.