Patent ID: 8373499

Claim:
A semiconductor integrated circuit having a normal operation mode and a self-refresh mode, comprising: a first internal step-down circuit which generates a first internal power supply voltage from a supplied external power supply voltage; a second internal step-down circuit which generates a second internal power supply voltage lower than said first internal power supply voltage, from the supplied external power supply voltage; and a switching unit which supplies said first internal power supply voltage output from said first internal step-down circuit to an internal circuit in said normal operation mode and supplies said second internal power supply voltage output from said second internal step-down circuit to said internal circuit in said self-refresh mode, wherein at a time of operation mode switching from said normal operation mode to said self-refresh mode, said switching unit activates said second internal step-down circuit at a timing earlier than a switching timing of operation mode and stops said first internal step-down circuit at said switching timing, and at a time of operation mode switching from said self-refresh mode to said normal operation mode, said switching unit activates said first internal step-down circuit at a switching timing of operation mode and stops said second internal step-down circuit at a timing later than said switching timing.