Patent ID: 7400126

Claim:
A DC regulated power supply which supplies a DC voltage regulated to a desired voltage to a load through power supply lines, the DC regulated power supply comprising: sensing means which senses a load current; correcting means which, in response to a sensing result of the sensing means, performs correction to increase an output voltage with respect to a predetermined voltage drop, which occurs in the power supply lines, corresponding to the load current; a transformer; a first smoothing circuit, connected to a secondary winding of the transformer, which smoothes output of the transformer; a second smoothing circuit which smoothes output of the first smoothing circuit, the sensing means being provided between an output of the first smoothing circuit and an input of the second smoothing circuit, and the sensing means includes a current sensing resistor which is inserted in series with the power supply lines for a secondary side; and a coil connected in series with the current sensing resistor that provides additional smoothing to the smoothing performed by the second smoothing circuit, the coil and the second smoothing circuit being provided at a rear stage of the current sensing resistor, wherein: the correcting means corrects the output voltage so that the output voltage becomes a total voltage of a base output voltage and a correction voltage, the base output voltage being a desired voltage to be supplied to the load, the correction voltage being equal to a product of impedance of the power supply lines and the load current sensed by the sensing means, the correcting means supplying the corrected output voltage, as the DC voltage regulated to a desired voltage, to the load through the power supply lines, the DC regulated power supply further comprising: control means which controls the output voltage so that a voltage supplied to the load becomes a desired voltage when a correction voltage is lower than a preset value, and, on the other hand, decreases the output voltage in such a manner that no over current occurs when the correction voltage is higher than or equal to the preset value.