Abstract: According to an aspect of the present invention, there is provided a power supply circuit including: a detection circuit that is connected to an external power supply voltage and that outputs a first signal indicating whether the external power supply voltage is in a dropped-state in which the external power supply voltage is dropped below a reference voltage; a control circuit that includes: a delay circuit that outputs a second signal acquired by delaying the first signal for a reference time; and a determination circuit that outputs a third signal based on the first signal and the second signal; a generation circuit that generates internal power supply voltage from the external power supply voltage and that supplies the internal power supply voltage; and an interruption circuit that interrupts the internal power supply voltage supplied from the generation circuit based on the third signal.

Abstract: A signal level shifting circuit, including an input stage circuit and an output signal latching circuit. The input stage circuit receives an input signal, wherein a voltage level of the input signal falls within a first predetermined voltage range. The output signal latching circuit is cascoded with the input stage circuit, and includes: a latching circuit for generating an output signal according to the input signal, wherein a voltage level of the output signal falls within a second predetermined voltage range, and the second predetermined voltage range is different from the first predetermined voltage range; and an activating circuit, coupled to the latching circuit, for selectively enabling or disabling the latching circuit, wherein when a level transition appears to the input signal, the activating circuit disables the latching circuit.