Schaltung zur Erzeugung künstlicher Zufallszahlenmuster

摘要

An artificial random-number pattern generating circuit has a plurality of flip-flops (11-14; 11-15) each having a set signal input terminal and a clock signal input terminal; a plurality of selectors (21-23,25,27; 21-24,26,28) each of which forwards its output to the corresponding flip-flop and receives a first operation mode signal (C1) and/or a second operation mode signal (C2); and an exclusive logical OR gate (30). The artificial random-number pattern generating circuit functions in three different ways, that is, as an artificial random-number pattern generator, a boundary scanning buffer or an input buffer, in accordance with the combinations of the first and second operation mode signals. The circuit can make not only a diagnosis of failure in the internal circuit of the LSI but also overall tests including those for input and output buffer circuits of the mounted LSI chip on a board or those for external wirings for the LSI.