| 摘要 |
PROBLEM TO BE SOLVED: To obtain a charging circuit of a secondary battery used as a primary power supply in which the charge control of the secondary battery is possible even if a DC power supply of a low voltage, e.g. a fuel cell or a solar cell is employed as a main power supply, a load apparatus is sustained in an available state in any situation, and high efficiency can be attained by minimizing power supply from the DC power supply with limited energy, and to provide its power supply switching method, and a power supply with a secondary battery charging circuit. SOLUTION: A power supply switching circuit section 12 detects voltage values of a first voltage V1 created by generating power from a first DC power supply 2 such as a fuel cell or a solar cell, a second voltage V2 created based on a power supply supplied externally from a second DC power supply 3 such as an AC adapter, and a secondary battery voltage Vb, i.e. a voltage of a secondary battery 4, and outputs a voltage of the highest voltage value as a power supply to a charging circuit 11. The charging circuit 11 is operated by the voltage inputted from the power supply switching circuit section 12 as a power supply. COPYRIGHT: (C)2007,JPO&INPIT |
