Patent ID: 7977889
Filing Date: 2011-07-12
Classification: H02M,H05B,Y02B

Abstract:
1. A direct-current power supply device, comprising: an inductor; a switching element to intermittently supply a current to the inductor; an output terminal connected to an external unit; a rectifying element connected between the inductor and the output terminal; a PFM comparator to generate a first pulse signal having a pulse width corresponding to a voltage proportional to an output current of the external unit, the output current being fed back to the direct-current power supply device from the external unit; a duty control circuit to generate a second pulse signal by controlling a pulse width of an oscillation signal having a predetermined frequency in response to an externally-supplied current control signal; a logic circuit configured to output the second pulse signal generated by the duty control circuit during a period when the first pulse signal generated by the PFM comparator is at a predetermined level; and a drive circuit to generate a drive signal for driving the switching element based on the second pulse signal output from the logic circuit and output the drive signal to the switching element.