| 摘要 |
PROBLEM TO BE SOLVED: To easily generate such voltage that a volatile memory in a potable electric apparatus can hold data at low cost by forming an integrated circuit out of a DC-DC converter generating the first and second boosting voltages having different boosting voltage from each other, and forming either of the first or the second boosting voltage into power supply voltage for the volatile memory. SOLUTION: A DC-DC converter 201 generates two types of boosting voltages 3 V, 9 V using battery voltage 0.9, the boosting voltage 3 V is supplied as power supply voltage for a liquid panel 202 and SRAM 205, and the boosting voltage 9 V is supplied as power supply voltage for a radio detection part 203. The DC-DC converter 201 is integrated on the same chip for the operating circuit 204 of a portable electronic apparatus. It is thus possible to generate two types of boosting voltages 3 V, 9 V easily for the low voltage of power supply voltage so that the SRAM 205 may hold data, and eliminate use of the DC-DC converter intended for the ratio detection 203, thereby attaining cost reduction.
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