| 摘要 |
PURPOSE:To make the rising time of an LSI, etc., faster and, at the same time, to reduce the manufacturing cost of the device by closing a cutoff means by means of an open/close controlling means and impressing a voltage across a transmission controlling means when a detecting means detects a signal to be transmitted from a transmission line. CONSTITUTION:Since the power supply to an LSI 25 and bus I/F circuit 26 which consume large power is disconnected by means of a switching circuit 24 and power supply is only made to a power supply stabilizing device 21, WU circuit 22, and CPU 23 when transmission/reception of transmission signals is not made for more than a fixed period of time, the current consumption of a battery can be prevented. In addition, since a stable voltage is impressed across the WU circuit 22 from the device 21, the need of providing a separate stabilization circuit and the need of providing a controller having a power supply turning on/off function to the device 21 are eliminated and the manufacturing cost can be reduced. Moreover, the time until the LSI 25 and bus I/F circuit 26 reach their normal operating states and they can make normal signal transmission/reception is reduced. |
