Accelerated scanning test due to the re-use the response data as stimulus data

摘要

PROBLEM TO BE SOLVED: To promote a scanning test by using the scanning test response of one circuit as scanning test stimulus data for another circuit. ;SOLUTION: A tester performs control so that all circuits C1-CN can be reset. After the reset, the tester controls circuits C1-CN to capture first response for reset stimulus data. Then, the tester controls the circuits C1-CN to shift data only for the length of the scanning path of the first circuit C1. After the first shift operation, stimulus data from the tester are loaded to the scanning path of C1, and response data from C1-CN-1 are loaded to the scanning paths of C2-CN. Then, in the case of a next capturing and shift operation, C1 outputs response data to a downstream circuit and receives next stimulus data from the tester. After a second capturing and shift operation, C1 includes second stimulus data pattern from the tester and C2-CN include a second stimulus pattern obtained from a response that is outputted from the previous circuits C1-CN-1.;COPYRIGHT: (C)1998,JPO