Test input vectors for supply current testing of TTL combinational circuits

Abstract

In this paper, test input vectors for ISCAS-85 benchmark circuits are derived, with which single faults of each signal line in the lTL combinational circuits can be detected by their quiescent supply currents. Also, they are compared with the vectors for fault detection methods based on the primary output logic values. It is shown that by detecting faults with supply currents of T7z circuits, smaller size of test inputs can be derived for most of the circuits than fault detection methods based on the primary output logic values, and ako, if both the output logic values and the supply current are used for detecting faults, the number of the test inputs can be reduced.

Supply current test for unit-to-unit variations of electrical characteristics in gates

“…It is found that open-circuit faults are very difficult to be detected from the test generation results in [6] and [7]. In order to examine the worst-case testability of our supply current testing, single open-circuit faults are attempted to be detected.…”

“…In the past, we proposed a random test generation algorithm [6] and a deterministic one [7]. The algorithms can be used for generating test input vectors, only by changing the criterion for judging whether 7;.…”

“…Also, we proposed two kinds of test generation algorithms for the supply current testing and derived the test input vectors of ISCAS-85 benchmark circuits, with which more faults can be detected than the logic testing [6,7]. In [6] and [7], the test inputs are derived in an ideal condition that there are not any unit-to-unit variations of supply current in logic gates. Thus the fault coverage obtained by the test inputs corresponds to the maximum one and is not practical one.…”

Practical Fault Coverage of Supply Current Tests for Bipolar ICs

“…With the distributions of the unfaulty circuit and a circuit having an open fault, it is determined whether an input vector can be selected as a test vector. In the past, we proposed a random test generation algorithm [4] and a deterministic one [5] for the supply current tests. In our experiments, test input vectors are derived by a modified random test input generation method, which is almost the same as in [6].…”

“…The method is to detect faults by measuring the quiescent supply current of a circuit under test and comparing it with one of the unfaulty circuit. Also, we proposed a fast random test input generation method for the supply current tests and an algorithmic one in [4] and [5], respectively.…”