SEMICONDUCTOR INTEGRATED CIRCUIT FOR DRIVING CROSS COIL

摘要

PROBLEM TO BE SOLVED: To improve the resolution of indicated value of an instrument without being accompanied with expansion of the circuit scale. SOLUTION: A cross coil PWM circuit 8 in a one-chip microcomputer 3 repeatedly outputs PWM signals with seven bits for driving a cross coil 2 from a first frame to a fourth frame every cycle. The number of combinations of pulse width data of the PWM signal of each frame is four using reference pulse width data and an adjusting pulse width data derived by adding '1' equivalent binary data to this. This, since average current (indicated value of an instrument) flowing through the cross coil 2 can be changed in four stags based on one reference pulse width data D, the resolution of the indicated value of the instrument is improved to a level equivalent to the case that the PWM signal with nine bits is stored only by storing the PWM signals with seven bits.