Patent ID: 7489118

Claim:
A DC stabilized power supply apparatus comprising: a voltage switching control circuit configured to generate first and second voltage switching signals in accordance with at least one voltage switching signal externally input thereto; a first power supply circuit configured to convert a power source voltage derived from a direct current power source into a first direct current voltage in accordance with the first voltage switching signal generated by the voltage switching control circuit; and a second power supply circuit configured to convert the first direct current voltage from the first power supply circuit into a second direct current voltage in accordance with the second voltage switching signal generated by the voltage switching control circuit; wherein 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, wherein the voltage switching control circuit controls the second power supply circuit to reduce the second direct current voltage to a first specific voltage and subsequently controls the first power supply circuit to reduce the first direct current voltage to a voltage corresponding to the first specific voltage, upon a receipt of the at least one voltage switching signal externally input such that the second direct current voltage is reduced to the first specific voltage.