Patent ID: 6452854
Filing Date: 2002-09-17
Classification: G11C,H01L

Abstract:
A power supply circuit for supplying an internal circuit of a semiconductor memory device with power from an external power supply, the power supply circuit comprising:a first power supply circuit connected to the external power supply and the internal circuit for generating a step down voltage by decreasing a first voltage on the external power supply and supplying the internal circuit with the step down voltage when the semiconductor memory device is in a normal operation mode; a second power supply circuit connected to the external power supply and the internal circuit for supplying the internal circuit with a second voltage on the external power supply when the semiconductor memory device is in a self-refresh mode; a detection circuit connected to the external power supply and the first and second power supply circuits for detecting entry to the self-refresh mode and a voltage level of the external power supply and generating a detection signal based on the detection of the entry and the voltage level, wherein the first power supply circuit receives the second voltage from the external power supply during the self-refresh mode, and the first and second power supply circuits supply the internal circuit with the second voltage based on the detection signal during the self-refresh mode.