| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a semiconductor device surely initializing each functional circuit at an input of power supply. Ž<P>SOLUTION: The semiconductor device includes: a voltage step-down circuits group having a plurality of voltage step-down circuits for stepping down an external power supply voltage to a predetermined voltage; a plurality of functional circuits requiring a reset operation at the input of power supply; and a power-on reset circuit for output a reset command to the plurality of functional circuits when it detects that the internal power supply voltage to be supplied from the voltage step-down circuits group exceeded a voltage level necessary for the initializing operation. The plurality of voltage step-down circuits of the voltage step-down circuits group are divided into a voltage step-down circuits group of start time operation for supplying the internal power supply by executing the voltage step-down operation from the input time of power supply and a voltage step-down circuits group of start time stop for not supplying the internal power supply by stopping the operation at the input time of power supply. The voltage step-down circuits group of start time stopping consists of the plurality of voltage step-down circuits selected in order of shortness of wiring distance from the power-on reset circuit. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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