| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device capable of sufficiently obtaining an EMI reducing effect, and a system on which the semiconductor device is mounted, in an LSI stepping down a supplied voltage supplied from an external source by a step-down circuit and driving an internal circuit by a power supply voltage after the voltage step-down. SOLUTION: The system is constituted of an LSI package for a microcomputer which is mounted on a mounting base board. The LSI package is provided with a terminal T1 for a supplied voltage VCC, a terminal T2 for a ground voltage VSS, a terminal T3 for the power supply voltage VCL after voltage step-down and a terminal T4 for the ground voltage VSL. A capacitor C2 is mounted between the terminal T3 and the terminal T4 and a by-pass capacitor C1 is mounted between the terminal T1 and the terminal T2 on the mounting base board while the terminal T4 for the ground voltage VSL is not connected actively to the terminal T2 for the ground voltage VSS whereby noise generated in the LSI package is prevented from being leaked into a basic power supply system on the mounting base board. COPYRIGHT: (C)2004,JPO |
