| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve efficiency of voltage step-up, in a flash memory built-in in a microcomputer. <P>SOLUTION: The semiconductor integrated circuit is provided with a booster circuit for generating step-up voltage by receiving prescribed voltage. The booster circuit, for generating the step-up voltage, comprises a charge pump circuit (47) having a step-up node connected to a MOS transistor and a capacitor, and a switching means (460) for switching substrate bias voltage so that the threshold of the MOS transistor, decreases from starting of step-up operation, until voltage output by the booster circuit reaches the step-up voltage. The threshold voltage of the MOS transistor becomes small, thereby electric charges are easily moved via the MOS transistor operating the charge pump. This fact improves the step-up operating efficiency so as to shorten the time until the prescribed step-up voltage is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
