| 摘要 |
PURPOSE:To facilitate the specification of a defective IC, by correlating the scanning signal from a scanning control circuit with the scanning signal obtained from a control signal from a system wherein the input control circuit and the output control circuit in the respective devices are connected in series sequentially. CONSTITUTION:IC devices B-Z are connected to a device A provided with a scanning control circuit 1 in series, and a scanning test circuit is formed. In each device B and the like, an input control circuit (FI), a shift register S, an output control circuit (FO) and the like are provided, respectively. The scanning signal outputted from the circuit 1 is inputted into the device B through an output signal switching circuit Oa. The signal is returned from the device Z so as to reach the circuit 1. The signal is correlated with the input scanning signal at first in the circuit 1. When the signal does not agree with the input signal, some of the devices are removed from a loop circuit, and the testing with the scanning signal is performed. Therefore the defective IC can be specified readily. |
