Technique for Vlsi In-Circuit Testing
Original Publication Date: 1988-Sep-01
Included in the Prior Art Database: 2005-Feb-15
In-circuit testing (ICT) is carried out to check that the I/O functions of a module on a card are working. Inputs and outputs are connected together via a simple logic test path which bypasses the internal module functions. Using an 'AND' bypass, selected test patterns set all the inputs to a high state to check that all outputs go high. Then each input, in turn, is set low to check that all outputs go low. These tests check that all input and output pin functions perform correctly. Many current cards are tested using well known ICT techniques. The basic requirement for these tests is that they guarantee operation of the I/O functions of the devices on the card (to reveal manufacturing-induced defects) without any particular necessity to test the internal function of the device (which is proved during module manufacture).