A power supply device including a register circuit, an internal control circuit, and a storage circuit is disclosed. The register circuit includes a first sub-register circuit and a second sub-register circuit. The first sub-register circuit and the second sub-register circuit are configured to take turns to temporarily store a data transmitted form an external control circuit. The internal control circuit is coupled to the register circuit, and the internal control circuit is configured to obtain the data temporarily stored in the first sub-register circuit and the second sub-register circuit. The storage circuit is coupled to the internal control circuit, and the storage circuit is configured to obtain the data from the internal control circuit and to store the data.