Abstract: A power factor correction circuit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, a seventh switch, a first inductance coil, a second inductance coil, a first capacitor, and a second capacitor. The first switch is connected to the second switch, the third switch, and the first inductance coil. The fifth switch is connected to the third switch and the second inductance coil. The sixth switch is connected to the first switch, the fourth switch, and the seventh switch. The seventh switch is further connected to the second switch, the first capacitor, and the second capacitor. The second inductance coil is further connected to the fourth switch and the first capacitor. The second capacitor is connected to the fourth switch, the sixth switch, and the first switch.

Abstract: A power supply circuit is provided. The power factor correction (PFC) circuit is used to perform a power factor correction according to a first voltage to generate an intermediate voltage. The first storage capacitor is used to store a first electrical energy related to the intermediate voltage. The boost conversion circuit is connected to the PFC circuit and used to generate an output voltage according to the intermediate voltage. The boost conversion circuit includes a first post-stage inductor, a first post-stage diode and a first post-stage transistor. The second storage capacitor is used to store a second electrical energy related to the output voltage. The capacitance value of the second storage capacitor is less than the capacitance value of the first storage capacitor; the first electrical energy is completely or partially transferred as the second electrical energy.

Abstract: A memory card with an indicator light has a casing, a processor, an input/output (I/O) interface, memory and an indicator light module. The indicator light module is mounted in the casing and connected to the I/O interface and has an inductor, an LED and a resistor. The inductor is connected to the I/O interface and has an input end and an output end. The LED is mounted on the casing and connected to the output end of the inductor. The resistor is connected in series with the LED. When the LED is not on, electrical power is not being provided to the proper pin on the I/O interface from the digital device. Consequently, any fault observed when the LED is not on can be attributed to a fault in the digital device.