The 'ABT8543 scan test devices with octal registered bus transceivers are members of the Texas Instruments SCOPETMtestability 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 'F543 and 'ABT543 octal registered bus transceivers. 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 SCOPETMoctal registered bus transceivers.

Data flow in each direction is controlled by latch-enable (and), chip-enable (and), and output-enable (and) inputs. For A-to-B data flow, the device operates in the transparent mode whenandare both low. When eitheroris high, the A data is latched. The B outputs are active whenandare both low. When eitheroris high, the B outputs are in the high-impedance state. Control for B-to-A data flow is similar to that for A-to-B, but uses,, and.Read more