The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 22, 1995
Filed:
Jun. 09, 1993
Jean-Claude Perraud, St. aubin S/Mer, FR;
U.S. Philips Corporation, New York, NY (US);
Abstract
An interface circuit for linking microprocessors, intended to limit the current (Iout) in the link (L1-L2) by inserting in the link the emitter-collector path of a first transistor (T.sub.1) which is in the saturated state during operation. This circuit includes a second transistor (T.sub.2) which has a geometry k times smaller than that of the first transistor (T.sub.1) and which is coupled to the first transistor (T.sub.1) so as to produce a copy (Iy) of the link current (Iout), and a base current generator (10) which produces an output current (Iz) which feeds the bases of the first and the second transistor (T.sub.1, T.sub.2), and which is a regressive function of the copy current (Iy), on the basis of a fixed reference current (I.sub.0). A pair of transistors (T.sub.3, T.sub.4), similar to the first and the second transistor (T.sub.1, T.sub.2) but connected to the link (L1-L2) in an inverted manner, provides protection for bidirectional operation. The interface circuit can be used for temporary links between different microprocessors, for example in chip cards.