N-detection under transparent-scan

We study the quality of test sequences under a test application scheme called transparent-scan as n-detection test sequences. We obtain transparent-scan sequences from combinational test sets. We show that for the same number of clock cycles required to apply a compact single-detection combinational test set, a transparent-scan sequence detects faults more times than the combinational test set. We note that a transparent-scan sequence based on a combinational test set contains unspecified values. We consider several procedures for specifying the unspecified values of the transparent-scan sequence, and study their effects. We also study the extension of a transparent-scan test sequence into an n-detection test sequence that detects every target fault at least n times.