| 摘要 |
PROBLEM TO BE SOLVED: To realize power-saving by improving the voltage conversion efficiency of DC/DC conversion. SOLUTION: A switching signal shows a large power mode in a photographing mode requiring large power consumption, and a power-saving mode in a reproduction mode requiring small power consumption; and is inputted to a power supply circuit 62 for executing the DC/DC conversion from a CPU 40. The large power mode and the power-saving mode are switched by a switch 66B corresponding to the switching signal inputted from the CPU 40 at a control unit 66 of the power supply circuit 62. The control unit 66 supplies the power to each part of a digital camera by executing the voltage conversion while executing synchronous rectification operations by driving both of FETs 72H, 72L for controlling and FETs 78H, 78L for synchronous rectification, in each of a step-up circuit 64H and a step-down circuit 64L of a DC/DC converter 64 in the large power mode. However, it supplies the power to each part by executing the voltage conversion by driving only the FETs 72H, 72L for controlling in a state of stopping the synchronous rectification operations by turning OFF the FETs 78 for the synchronous rectification in the power-saving mode. COPYRIGHT: (C)2005,JPO&NCIPI
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