Testability of the Philips 80C51 micro-controller

This paper presents the research results of the sequential testability of the Philips 80C51 microcontroller. The motivations for this research were to save chip area and test application time (i.e., reducing the production costs), and to evaluate the effectiveness and efficiency of the Delft Automatic Test (DAT) generation system for sequential circuits on real industrial sequential circuits, such as the 80C51. ATPG has been performed on a fully sequential version (non-scan), and on several partial-scan versions of the 80C51. The stuck-at fault coverage of the full-scan version is above 91%, while the fault coverage of the non-scan version is almost zero. Therefore, partial-scan versions of the 80C51 have been developed to achieve the fault coverage level of the full-scan version. Experimental results demonstrate that almost 50% of the FFs have to be scannable in order to approach the fault coverage of the full-scan version. The fault coverage is reduced by ±10%, when ±30% of the FFs have been selected for scan