Patent ID: 7479799
Filing Date: 2009-01-20
Classification: H03K

Abstract:
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: 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.