Rohm Co., Ltd.

Hiroaki Asazu

Kunihiro Komiya

Atsushi Kitagawa

A direct-current stabilized power supply apparatus according to the present invention includes offsetting means that keeps a slope voltage (Vslp) shifted from the ground potential to a higher potential by a predetermined offset voltage &#x394;V so that the lower limit level of the slope voltage (Vslp) is higher than that of an error voltage (Verr). With this configuration, it is possible to provide a direct-current stabilized power supply apparatus that can appropriately control a duty ratio without causing oscillation or the like in the overall system, and also to provide an electrical device incorporating such a power supply apparatus.

PWM power supply apparatus having a controlled duty ratio without causing overall system oscillation

A voltage generation unit generates a driving voltage for driving an LED. A first feedback path feeds back a voltage according to a voltage at one end of the LED. A second feedback path feeds back a voltage according to a voltage at the other end of the LED. A current driving circuit is provided on a path on which the voltage generation unit drives the LED. A control circuit controls the voltage generation unit so that one of first and second feedback voltages fed back by the first and second feedback paths, respectively is closer to a predetermined reference voltage.

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Kyoto, Japan

Hiroaki Asazu