The 'ABT8543 scan test devices with octal registered 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)
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 SCOPETM octal
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 when and are both low. When either or is high, the A data is latched.
The B outputs are active when and are both low.
When either or 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 ,
, and .
In the test mode, the normal operation of the SCOPETM
registered bus transceiver 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 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
The SN54ABT8543 is characterized for operation over the full
military temperature range of -55°C to 125°C. The
SN74ABT8543 is characterized for operation from -40°C to
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