Patent ID: 6870778
Filing Date: 2005-03-22
Classification: G06F

Abstract:
1. A semiconductor device in which an operational mode is selected from among a number of operational modes, comprising: a voltage-decreasing regulator converting a source voltage into an output voltage in accordance with a control signal, the regulator supplying the output voltage to an internal module of the semiconductor device via a power line; an analog-to-digital converter converting the output voltage received from the power line, into an output signal which indicates a value of the received output voltage; and a voltage monitoring circuit having a control register that holds a value predetermined for the selected operational mode, and generating the control signal based on a result of comparison between the value indicated by the output signal of the converter and the value held by the control register, wherein the voltage monitoring circuit outputs the control signal to the regulator so that the regulator supplies the output voltage, which is adjusted to an optimal output voltage for the selected operational mode by the control signal, to the internal module.