Hi reliability fault tolerant terminating resistor

Abstract

A data bus for a fault tolerant avionics digital autonomous terminal access communications system is provided with a terminating resistor for absorbing or sufficiently attenuating signals incident on it so that they are not reflected back into the transmission line at amplitudes where they would cause distortion of the data signal. The data bus and terminating resistors are designed to continue providing full operational capability even if the electrical resistance of the terminating resistor increases by about 5%. The terminating resistor has at least about twenty resistive elements connected in parallel across two conductors in the data bus at one end thereof. Each resistive element includes a non-conductive substrate having a face surface on which is deposited a conductive film to produce a primary resistor. Leads on the substrate establish electrical contact with each of the bus conductors, and a coating of non-conductive glass frit is applied over the conductive film to protect the film from mechanical damage and prevent shorting of the film. Each resistive element has about the same electrical characteristics as the other elements and is designed to fail by opening rather than by shorting. Failure of one of the resistive elements increases the resistance of the terminating resistor by no more than about 5%, so the data bus remains fully operational despite the failure.

Dependencies are inferred from the claim text.