SN74ABT8952

The 'ABT8952 scan test devices with octal registered bus transceivers are members of the Texas Instruments SCOPEE testability integrated-circuit family. This  'ABT8952  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  'ABT8952  devices are functionally equivalent to the 'BCT2952 and 'ABT2952 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 SCOPEE octal registered bus transceivers.

Data flow in each direction of  'ABT8952  is controlled by clock (CLKAB and CLKBA), clock-enable (CLKENAB and CLKENBA), and output-enable (OEAB and OEBA) inputs. For A-to-B data flow, A-bus data is stored in the associated registers on the low-to-high transition of CLKAB, provided that CLKENAB is low. Otherwise, if CLKENAB is high or CLKAB remains at a static low or high level, the register contents are not changed. When OEAB is low, the B outputs are active. When OEAB is 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 CLKBA, CLKENBA, and OEBA.

In the test mode, the normal operation of the   'ABT8952  SCOPEE registered 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 performs boundary-scan test operations as described in IEEE Standard 1149.1-1990.

Four dedicated test pins of  'ABT8952  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 SN54ABT8952 is characterized for operation over the full military temperature range of 55°C to 125°C.The SN74ABT8952 is characterized for operation from 40°C to 85°C.