Patent ID: 6201428
Filing Date: 2001-03-13
Classification: H03K

Abstract:
A buffer/driver apparatus having an input terminal and an output terminal, said buffer/driver apparatus comprising:a level-shifter circuit that operates on an input signal on the input terminal to provide output signals, a pull-up signal and a pull-down signal, with wider voltage swings than the input signal,the level shifter circuit including:connections to power supplies, receiving supply voltages, including an operating voltage, an intermediate voltage and a ground level voltage,a differential pair of transistors, one driven by the input signal and the other by an inverted signal of the input signal, directing a current through two different paths,a cross-coupled pair of transistors driven by said current to switch the pull-up signal between the intermediate voltage and the operating voltage, anda series of inverters operatively connected to the input signal at its input and to the pull-down signal at its output, said series of inverters operating to drive the pull-down signal, such that the pull-down signal switches between the ground level voltage and the intermediate voltage;a push-pull circuit operatively connected to the level-shifter circuit, such that output signals of said level shifter circuit controls the push-pull circuit to provide sufficient capability at the output terminal to drive a particular interface connected to the output terminal; andan over-voltage detect circuit connected to detect particular voltages at the output terminal, such that an amount of operation of the push-pull circuit can be limited if the particular voltages are detected.