| 摘要 |
PURPOSE:To improve the operating margin, operating speed and the reliability of a semiconductor LSI device by forming on a chip a programmable step-down power source circuit capable of variably setting a voltage value by the connection or disconnection of a fuse element and an MOS LSI circuit which operates by the output voltage of the power source circuit, and setting the voltage by the power source circuit. CONSTITUTION:The source and drain of a step-down P-channel type MOS transistor TP are respectively connected between an external supply power terminal Vcc and an internal step-down power line LINT, and controlled to be conducted by the output of an operational amplifier. Accordingly, a voltage VINT on the power line LINT becomes the same value as the constant voltage output value Vi set by the connection or disconnection of a fuse. The voltage values VF when forward currents flow to diodes D1-D8 might be different according to each process, and the operating voltage of the MOS LSI circuit is different at every process or performance. Accordingly, the fuse elements F1-F8 are sequentially fused or conducted by a laser or the like, thereby obtaining an optimum voltage VINT. |
