Patent ID: 6856173

Claim:
An integrated circuit die comprising: a multiplexer having a first terminal coupled to a first digital signal line that when at a first state is at a voltage dependent upon a first power supply voltage, a second terminal coupled to a second digital signal line that when at a first state is at voltage dependent upon a second power supply voltage, and a third terminal, the multiplexer receiving a control signal, the multiplexer coupling its third terminal to one of at least its first terminal or its second terminal based upon the control signal; a level shifter having a first signal terminal coupled to the third terminal of the multiplexer, a second signal terminal coupled to a third circuit, and a voltage supply terminal; and a second multiplexer having a first terminal coupled to receive a voltage dependent upon the first power supply voltage, a second terminal coupled to receive a voltage dependent upon the second power supply voltage, and a third terminal coupled to the voltage supply terminal of the level shifter, the second multiplexer receiving a second control signal, wherein the second multiplexer provides at its third terminal a voltage of one of at least a voltage of its first terminal or a voltage of its second terminal based upon the second control signal.