Abstract: A hybrid switching circuit includes first and second switching devices containing first and second unequal bandgap semiconductor materials. These switching devices, which support parallel conduction in response to first and second control signals, are three or more terminal switching devices of different type. For example, the first switching device may be a three or more terminal wide bandgap switching device selected from a group consisting of JFETs, IGFETs and high electron mobility transistors HEMTs, and the second switching device may be a Si-IGBT. A control circuit is also provided, which is configured to drive the first and second switching devices with first and second periodic control signals having first and second unequal duty cycles. The first duty cycle may be greater than the second duty cycle and the active phases of the second periodic control signal may occur exclusively within the active phases of the first periodic control signal.

Abstract: A radiator fan driving module applied to a power system/power supply device is configured as a single unit on which a fan driving circuit is designed, whereby the amount of the radiator fans is easy to be varied based on requirements of the power system. The fan driving circuit controlled by a PWM circuit applies a DC voltage to the radiator fan whereby the radiator fan is driven at a PWM voltage with a non-zero low level voltage, thus the driving current to the radiator fan is smooth and the lifetime of the radiator fan is prolonged because stress that the radiator fan bearing bear is minimized. The PWM circuit further addresses temperature and load condition to improve the operation efficiency of the radiator fan by speeding up while temperature is too high, and slowing down while the load that the power system experiences is light.