The 'LVTH18646A and 'LVTH182646A scan test devices with 18-bit bus transceivers and registers are members of the Texas Instruments (TI) SCOPE testability integrated-circuit family. This family of devices 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 4-wire test access port (TAP) interface.

Additionally, these devices are designed specifically for low-voltage (3.3-V) V_CC operation, but with the capability to provide a TTL interface to a 5-V system environment.

In the normal mode, these devices are 18-bit bus transceivers and registers that allow for multiplexed transmission of data directly from the input bus or from the internal registers.