Patent ID: 8138814

Claim:
A signal driver for an interface circuit, said signal driver comprising: a first stage level shifter operable to accept input signals and to output signals at a first signal level; a second stage level shifter coupled to said first stage level shifter and operable to output signals at a second signal level, wherein electronic components of said first stage level shifter and said second stage level shifter have reliability limits less than said second signal level, and wherein said first stage level shifter and said second stage level shifter are configured to apply to said electronic components only terminal to terminal signal levels within said reliability limits when processing signals for output at said second signal level; wherein said second stage level shifter is operable to selectively output signals at said first signal level and said second signal level, and wherein said first stage level shifter and said second stage level shifter are configured to apply to said electronic components only terminal to terminal signal levels within said reliability limits when processing signals for output at said first signal level and said second signal level; wherein said second stage level shifter is biased with a first bias voltage when processing signals for output at said first signal level and biased with a second bias voltage when processing signals for output at said second signal level, said first bias voltage being less than said second bias voltage; and a mode control circuit selectively providing said first bias voltage and said second bias voltage to said second stage level shifter.