The ’ABT8646 and scan test devices with octal bus transceivers and registers are members of the Texas Instruments SCOPE™ testability integrated-circuit family. This family of devices supports IEEE Standard 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.

In the normal mode, these devices are functionally equivalent to the ’F646 and ’ABT646 octal bus transceivers and registers. 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. Activating the TAP in normal mode does not affect the functional operation of the SCOPE™ octal bus transceivers and registers.

Transceiver function is controlled by output-enable (OE)\ and direction (DIR) inputs. When OE\ is low, the transceiver is active and operates in the A-to-B direction when DIR is high or in the B-to-A direction when DIR is low. When OE\ is high, both the A and B outputs are in the high-impedance state, effectively isolating both buses.Read more