The VCCT module serializes parallel test patterns so that they can be applied through the boundary scan path to detect manufacturing faults on non-scan logic surrounded by boundary scan devices. VCCT can be used to test an individual non-scan component – such as a memory device – or a cluster of non-scan devices. VCCT can also apply a combination of serial and parallel test patterns to test the non-scan logic. When both serial and parallel test patterns are used, VCCT automatically synchronizes the application of serial patterns at scan cells with parallel patterns at the ParallelRiter™ card or tester channels.

VCCT patterns can also be applied through the ParallelRiter™ card to test and assembly’s I/O pins.
VCCT uses the scan cells of boundary-scan devices as virtual channels to drive stimuli into the non-scan logic devices or clusters and detect responses from them. Stimulus patterns are conventional parallel test patterns which, VCCT regenerates into a serial format to apply via the boundary-scan path. Patterns for component test may be available from an in-circuit test library, a design pattern library, or they may have to be generated manually. VCCT testing includes the following capabilities:

• Detection of open and stuck-at faults on non-scan devices or clusters of non-scan devices using the scan chain
• Elimination of physical access requirements for testing conventional parts surrounded by boundary scan devices
• Automatic analysis to identify stimulus and measurement points for components
• Automatic serialization of parallel patterns to test non-scan devices or clusters
• Synchronous application of serial test patterns through the boundary-scan cells and parallel test patterns through the ParallelRiter™ card or in-circuit test channels