| 摘要 |
PURPOSE:To facilitate an easy inspection of a logical circuit, by incorporating a random pattern generating circuit, a counter circuit and a checking circuit of the counter circuit into the logical circuit and giving a self-inspecting function to the logical circuit. CONSTITUTION:The count value is cleared for counter circuits 601-60N, and the logic value of an external input terminal 1000 is set at 1. Thus a selecting circuit 300 feeds the signals to a logical circuit part 400 from outputs 201-20M of a random pattern generating circuit 200. While the circuits 601-60N count the changing frequencies for the output of each of outputs 501-50N of a gate. Then the count values of the circuits 601-60N are compared with correct count values which are stored in checking circuits 701-70N. Thus 0 and 1 are respectively fed to an OR gate 800 when the coincidence is obtained and no coincidence is obtained from the above-mentioned comparison. If the result of the OR operation is equal to logic value 1, it is decided that the logical circuit has a fault. |
