Semiconductor integrated circuit having a voltage stepdown mechanism

A semiconductor integrated circuit, adapted for receiving a chip selection signal, comprising:

• an internal circuit having a node;
• means for receiving a supply voltage;
• voltage detecting means for detecting a value of the supply voltage to generate a control signal;
• first voltage stepdown means for operating in one of
• an active mode for stepping down the supply voltage to apply a voltage to the node, and
• an inactive mode, the first voltage stepdown means operating in either the active mode or in the inactive mode in response to the control signal and the chip selection signal;
• second voltage stepdown means for operating in one of
• an active mode for stepping down the supply voltage to apply a voltage to the node, and
• an inactive mode, the second voltage stepdown means operating in either the active mode or in the inactive mode in response to the control signal;
• and
• means, responsive to the voltage detecting means, for switching the receiving means to the node at times when the first and second voltage stepdown means are both operating in the inactive mode.

A semiconductor integrated circuit, adapted for receiving a chip selection signal, comprising:

• an internal circuit having a node;
• means for receiving a power supply voltage;
• voltage detecting means for detecting a value of the supply voltage to generate a first control signal to indicate whether the value of the supply voltage is less than a first predetermined value and a second control signal to indicate whether the value of the supply voltage is less than a second predetermined value;
• first voltage stepdown means for operating in one of
• an active mode for stepping down the supply voltage to apply a voltage to the node, and
• an inactive mode, the first voltage stepdown means operating in either the active mode or in the inactive mode in response to the first control signal and the chip selection signal;
• second voltage stepdown means for operating in one of
• an active mode for stepping down the supply voltage to apply a voltage to the node, and
• an inactive mode, the second voltage stepdown means operating in either the active mode or in the inactive mode in response to the first control signal;
• and
• means, responsive to the second control signal, for switching the receiving means to the node in response to the second control signal.