Abstract: There is disclosed a synchronized rectifier type switching power source device in which losses and noise generation due to differences in operating delay times in the input and output switching elements can be suppressed. A signal timing adjusting device is provided for controlling the timing of the control signal applied to the first switching device provided in the input side and those of the control signals applied to the second and third switching devices provided in the output side, so that the control signal is applied to the first switching device with a timing delayed as compared with the timings of the control signals applied to the second and third switching devices to thereby compensate for the operating time delay among the first switching device and the second and third switching devices due to the differences in the voltage durability and the current capacity among these switching devices.

Abstract: A switching power source device in which recovery current can be decreased. The power source device includes a magnetic element connected one of terminals of a power source section, a switch having one end connected with the magnetic element and the other end connected with the other terminal of the power source section, a smoothing capacitor connected between the magnetic element and the other terminal of the power source section, and a diode connected between the magnetic element and the smoothing capacitor with forward direction directed to pass current from the power source section through the magnetic element to the smoothing capacitor.

Abstract: Device including an input rectifying circuit 2 for effecting a full wave rectification on an AC input, and an output converter which includes a transforming device 11 having a primary winding 11a and a secondary winding 11b, the primary winding being connected through an inductor 16 with paired outputs of the input rectifying circuit, the secondary winding being connected through an output rectifying circuit with a load. Switching element 18 is controlled by a control circuit 20 to operate between ON and OFF states, and capacitor 19 is connected with the input rectifying circuit and the transforming device so as to be charged during the OFF state period of the switching element 18 through a charging circuit including the inductor 16, and to discharge during the ON state period through the primary winding 11a of the transforming device 11. The control circuit 20 controls the switching element to operate in an ON-OFF manner with a frequency faster than the frequency of the AC input.