| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To achieve excellent power supply responsiveness, both when the operation of an object circuit is started and when its operation is finished, in a situation that an external power supply voltage is dropped to supply it to the object circuit. <P>SOLUTION: A step-down circuit 120 is connected between a power supply node 110 for supplying a system power supply voltage VDD0 and an internal power supply line for supplying power to an object circuit, and drops the VDD0 to supply it to the object circuit via the internal power supply line. The step-down circuit 120 is provided with: a comparison circuit 122 which compares a reference voltage VREF with a voltage VINT on the internal power supply line; and a driver 128 which adjusts currents flowing between the internal power supply line and a power supply node 130 according to the result of the comparison in the comparison circuit 122. The activity level of the driver 128 is controlled so that it may be strengthened, in synchronization with the star-up of the operation of the object circuit, in a prescribed strengthening period and be weakened in a prescribed weakening period after the strengthening period. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
