Semiconductor integrated circuit device

Abstract

A semiconductor integrated circuit device for transmitting data between a plurality of circuit blocks at least one thereof including a sequential circuit and enabling the circuit blocks to test in a scan testing type which has a plurality of scan registers provided between the plurality of circuit blocks corresponding to the number of bits of data to be transmitted for outputting the output data of the previous stage circuit block as it is at ordinary operating time and for holding and outputting the output data of the previous circuit block or test data for scan test synchronously with an external clock at testing time so that the circuits are connected by a shift register pass in such a manner that the entirety has one shaft register function, and a latch circuit provided at its data input terminal to the data output terminal of the corresponding scan register for outputtting the output data of the corresponding scan register as it is to the circuit block of next stage at ordinary operation time and holding the output data of the corresponding scan register before the scanning operation in a scan mode at testing time to continuously apply the data to the circuit block of next stage and holding and outputting the output data of the corresponding scan register in a test mode synchronously with the external clock, test data setting means for setting serial data of test from the exterior of the circuit device to each of the scan registers, test result outputting means for sequentially outputting the data of each scan register as serial data out of the circuit device, and operation switching means for switching the ordinary operation and the testing operation and switching the scan mode and the test mode, thereby enabling the semiconductor integrated circuit device to be readily subjected to a scan test together with circuit blocks including asynchronous sequential circuits.