Texas Instruments Corporation

Daniel D Edmonson

Bernhard H Andresen

Jeffrey A Niehaus

Robert J Landers

Mark G Harward

An output buffer includes a pair of P-channel transistors and two cascode pull-down N-channel transistors to drive an output node. The output pull-up transistor has the gate thereof connected through a P-channel control transistor to an input driving signal. The control signal is isolated from the output node by a P-channel transistor which only conducts during overvoltage conditions. During normal operation, the control transistor is maintained in a conductive state to allow the gate of the output pull-up transistor to be pulled high and low. During an overvoltage condition, the P-channel transistor connected between the output node and the control transistor is turned on in order to effectively turn off the control transistor. The P-channel transistors in the output buffer are floating well-type transistors with the wells thereof tied to a switched voltage that is either the supply voltage during the normal operating mode or the output node during overvoltage conditions.

5 volt tolerant I/O buffer circuit

Programmable circuitry (10) is provided including a plurality of logic modules (12) each having at least one input conductor (16). A nearest neighbor conductor (36) is fusibly coupled to output circuitry (25) of a selected logic module (12), the nearest neighbor conductor (36) intersecting the input conductor (16) of a nearest neighbor logic module (12). A fuse (40) disposed at the intersection of the nearest neighbor conductor (36) and the input conductor (16) of the nearest neighbor logic module (12) is provided for selectively establishing electrical coupling therebetween.

Growing community of inventors

Carrollton, TX, United States of America

Daniel D Edmonson