To suppress a reverse current to a power line resulting from series resonance caused by a parasitic inductance of the power line and a capacitive component of an external decoupling capacitor.
A series connection of a transistor section 1 and a transistor Tr3 and a series connection of a transistor section 2 and a transistor Tr4 are connected in parallel between power lines, and the transistor sections 1, 2 comprise parallel connections of transistors Tr1a and Tr1b and transistors Tr2a and Tr2b different in transistor size, respectively. In intervals where a PWM input signal PWM is at an H level, the transistors Tr1a, Tr1b, Tr4 are turned on and the others are turned off to supply a current to a coil 5, and in intervals of an L level, the transistor Tr1a is turned off with the transistors Tr1b, Tr4 kept on to generate an offset current for reverse flow prevention while regenerating the current to the coil 5.
Megumi Konishi
Hide Tanaka Tetsu