Methods and apparatuses for generating DC stabilized power are described. A DC stabilized power supply apparatus includes a voltage switching control circuit and first and second power supply circuits. The voltage switching control circuit generates first and second voltage switching signals in accordance with at least one voltage switching signal. The first power supply circuit converts a power source voltage into a first direct current voltage in accordance with the first voltage switching signal. The second power supply circuit converts the first direct current voltage into a second direct current voltage in accordance with the second voltage switching signal. In this apparatus, the voltage switching control circuit controls the first power supply circuit to generate the first direct current voltage such that the first direct current voltage is a minimal input voltage needed for the second power supply circuit to generate the second direct current voltage.