Patent Document ID: 7479799
Application ID: 11376593
Patent Status: 1

Claim One:
1. An output buffer, comprising: a first drive circuit having an output adapted to drive a signal line terminated with a termination resistor; and a means for switching the output impedance of said first drive circuit between a first, relatively low output impedance when said output buffer is operated in a first mode and a second output impedance which is greater than said first output impedance when said output buffer is operated in a second mode, so as to reduce the power dissipation in said termination resistor when said output buffer is operated in said second mode; wherein said output buffer is connected between and powered by first supply voltage VDD and a second supply voltage, said means for switching the output impedance of said drive circuit comprising: an n-type transistor connected between V DD and said output; and a p-type transistor connected between said output and said second supply voltage; said buffer arranged to operate said transistors so as to increase the effective output impedance of said drive circuit when said output buffer is operated in said second mode.