To provide a PWM signal generation circuit capable of changing an oscillation frequency of a PWM signal and a semiconductor device therewith which implement a noise reduction.
For example, the PWM signal generation circuit includes a triangular wave generation circuit for generating a triangular wave (Vrmp), and a PWM comparison circuit for comparing the triangular wave (Vrmp) with a reference voltage (Vref) and generating a PWM signal having a duty depending on the level of the reference voltage (Vref). The triangular wave generation circuit changes an oscillation frequency of the triangular wave (Vrmp) by changing the slope of at least either of the rise and fall of the triangular wave (Vrmp) at a transition timing (TS1a-TS1d, TS2a-TS2c) of the rise or fall. This keeps a constant on duty of the PWM signal irrespective of the change in the oscillation frequency.
Atsushi Sugada
Akiko Tsutsui
Tetsuya Sakaji
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