SN74ABT8245DWR

八进制总线收发器扫描测试设备 SCAN TEST DEVICES WITH OCTAL BUS TRANSCEIVERS

The "ABT8245 scan test devices with octal bus transceivers are members of the Texas Instruments SCOPETM 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 "F245 and "ABT245 octal 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 SCOPETM octal bus transceivers.

Data flow is controlled by the direction-control DIR and output-enable inputs. Data transmission is allowed from the A bus to the B bus or from the B bus to the A bus, depending on the logic level at DIR. The output-enable input can be used to disable the device so that the buses are effectively isolated.

In the test mode, the normal operation of the SCOPETM bus transceivers is inhibited and the test circuitry is enabled to observe and control the I/O boundary of the device. When enabled, the test circuitry can perform boundary-scan test operations as described in IEEE Standard 1149.1-1990.

Four dedicated test pins control the operation of the test circuitry: test data input TDI, test data output TDO, test mode select TMS, and test clock TCK. Additionally, the test circuitry performs other testing functions such as parallel-signature analysis PSA on data inputs and pseudo-random pattern generation PRPG from data outputs. All testing and scan operations are synchronized to the TAP interface.

The SN54ABT8245 is characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ABT8245 is characterized for operation from -40°C to 85°C.