R96MFX test strategy

摘要

The author describes the design for test features and overall test strategy for the R96MFX integrated circuit. This product is a 9600-b-per second half duplex modem used in facsimile equipment. It is implemented by two separate silicon dies mounted within one 64-pin package. Each of these two circuits had been previously designed and used in separate packages, so combining them in one package resulted in an I/O (input/output) pin consolidation which seriously limited the circuits' controllability and observability. The test strategy utilized to solve this limitation relies on the complementary test that IC manufacturers may perform; that is, they may thoroughly test a device at the wafer level and then test the device again after packaging for those failures induced by the packaging process. A self-test feature was implemented in the firmware instructions in one of the two chips thereby enabling extensive testing to be accomplished in spite of the controllability/observability limitations.