Pseudo-memory circuit for testing for stuck open faults

摘要

A method and apparatus are disclosed for testing for stuck- open faults in integrated circuits (10) having a plurality of combinational logic devices (18, 20). The apparatus includes a chain of shift register stages (22), with each stage including at least two latches (L1 and L3). The bits of an initialization test are shifted down the shift register and loaded into one of the latches (L3), while the bits of a detection test pattern are subsequently shifted down the chain and stored in the other latch (L1). A multiplexer (50) is provided for selecting one of the outputs from the two latches (L1, L3) so that the initialization test pattern and then the detection test pattern can be quickly applied to the combinational logic so as to minimize hazards which could invalidate the test results.