Patent ID: 6407538
Filing Date: 2002-06-18
Classification: G05F

Abstract:
A voltage down converter comprising a first voltage down converting circuit to lower an external power supply voltage on a first input node to generate an internal power supply voltage at a first output node, and a second voltage down converting circuit to lower said external power supply voltage on a second input node to generate said internal power supply voltage at a second output node, for operating an internal circuit by said internal power supply voltage generated on said first output node or said second output node,said first voltage down converting circuit including; a first voltage down converting partial circuit to lower said external power supply voltage by passing an operating current from said first input node to said first output node to generate said internal power supply voltage on said first output node, and a digital driving circuit to drive said first voltage down converting partial circuit to maintain a voltage on said first output node at said internal power supply voltage by varying said operating current stepwise according to a level of said external power supply voltage or said internal power supply voltage only during a period when said internal power supply voltage falls below a predetermined voltage, said second voltage down converting circuit including; a comparison circuit to perform an operational amplification on a result of comparison of said internal power supply voltage on said second output node and an internal reference voltage to output the result of amplification, and a second voltage down converting partial circuit to receive an output of said comparison circuit and to lower said external power supply voltage to generate said internal power supply voltage on said second output node.