Self-diagnostic circuit for logic circuit block

摘要

A self-diagnostic circuit comprises a plurality logic of circuits to be diagnosed and a plurality of first and second storage circuits provided for the logic circuits respectively. The first storage circuits have outputs which indicate whether or not the corresponding logic circuits are being diagnosed. The second storage circuits stored results of diagnoses of the corresponding logic circuits. The first and second storage circuits and logic circuits have a sequential diagnostic operation mode in which logic circuits are sequentially diagnosed according to a diagnosis starting signal, and a scan operation mode in which a specific one among the logic circuits is selected and diagnosed. The scan operation mode is realized during the supply of the diagnosis starting signal and by supplying selection signals that select the specific one among the logic circuits.