Abstract: A PWM signal generating circuit according to the invention includes a digital PWM signal generating circuit that generates a digital PWM signal having a resolution of 2n based on a clock signal CLK and n-bits (n?1) of digital information; a triangular wave generator that generates a triangular wave (e.g. ramp wave) synchronized with the clock signal CLK; and a comparator that compares the triangular wave with a threshold value. The PWM signal generating circuit increases the resolution of the digital PWM signal based on an output from the comparator.

Abstract: A dual power supply system for a vehicle includes a generator that generates an electric power by using a rotation output of an engine, a DC/DC converter connected to the generator, and a battery, connected to the generator, that supplies an electric power.

Abstract: A PWM signal generating circuit according to the invention includes a digital PWM signal generating circuit that generates a digital PWM signal having a resolution of 2n based on a clock signal CLK and n-bits (n?1) of digital information; a triangular wave generator that generates a triangular wave (e.g. ramp wave) synchronized with the clock signal CLK; and a comparator that compares the triangular wave with a threshold value. The PWM signal generating circuit increases the resolution of the digital PWM signal based on an output from the comparator.