This scan test device with a 18-bit bus transceiver and register is a member of the Texas Instruments SCOPE? testability IC family. This device supports IEEE Std 1149.1-1990 boundary scan to facilitate testing of complex circuit board assemblies. Scan access to the test circuitry is accomplished via the four-wire test access port (TAP) interface.

In the normal mode, this device is an 18-bit bus transceiver and register that allows for multiplexed transmission of data directly from the input bus or from the internal registers. It can be used either as two 9-bit transceivers or one 18-bit transceiver. The test circuitry can be activated by the TAP to take snapshot samples of the data appearing at the device pins or to perform a self-test on the boundary test cells.