| 摘要 |
A power supply circuit for supplying a semiconductor memory device with power to perform refreshing. The power supply circuit is connected to an external power supply. The power supply circuit includes a first power supply circuit, which generates a step down voltage by decreasing a first voltage on the external power supply in a normal operation mode, a second power supply circuit, which supplies the internal circuit with a second voltage on the external power supply in a self-refresh mode, and a detection circuit, which detects entry to the self-refresh mode and a voltage level of the external power supply and generates a detection signal based on the detection. During the self-refresh mode, the first power supply circuit receives the second voltage from the external power supply, and the first and second power supply circuits supply the internal circuit with the second voltage based on the detection signal.
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