Switching power supply device, and adjustable power supply system including the same

摘要

According to one embodiment of the invention, there is provided a switching power supply device including a rectifying circuit and a switching operation conversion circuit. The rectifying circuit receives a phase-controlled alternating voltage to rectify to a direct voltage. The switching operation conversion circuit starts up by being applied with the direct voltage, and includes a normally on type switching element and an off driving circuit. The normally on type switching element passes an input current, and the off driving circuit turns off the switching element when the input current reaches a prescribed value. The switching operation conversion circuit converts the direct voltage to an output voltage different from the direct voltage by repeating a switching operation of turning on and off the switching element.

主权项

1. A switching power supply device comprising:
a rectifying circuit configured to receive a phase-controlled alternating voltage to rectify to a direct voltage; and a switching operation conversion circuit configured to convert the direct voltage to an output voltage different from the direct voltage, the switching operation conversion circuit including
a switching element being of a normally on type and having a main terminal and a first control terminal, the direct voltage being applied to the switching element,a current control element having at least a second control terminal, the current control element configured to turn off the switching element by lowering a potential of the first control terminal than a potential of the main terminal when a current passing through the current control element exceeds a prescribed value,an inductor passing a current when the switching element is of an on-state, anda driving winding configured to control turning on or off the switching element by magnetically coupling with the inductor and supplying an induced voltage to the first control terminal, an end of the driving winding being connected to the inductor, another end of the driving winding being connected to the first control terminal.