| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To restrain power consumption in USB communication when the residual level of a battery gets low, so as to prolong an operable time for the whole equipment, in a USB host device coping with the "High-speed" of a USB standard operated by the battery. <P>SOLUTION: In this USB host device 100 coping with the "High-speed" of the USB standard operated by the battery, a USB communication speed is changed from the "High-speed" to "Full-speed", and an operation clock frequency for a CPU 102 and various circuits is changed to a clock frequency for "Full-speed" communication, when the residual level of the battery is judged to come to a prescribed capacity or less and when the USB communication speed is the "High-speed". <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
