SN74BCT8373 Datasheet, PDF (13/21 Pages) Texas Instruments – SCAN TEST DEVICE WITH OCTAL D-TYPE LATCHES

SN74BCT8373
SCAN TEST DEVICE
WITH OCTAL DĆTYPE LATCHES
SCBS471 − JUNE 1990 − REVISED JUNE 1994
pseudo-random pattern generation (PRPG)
A pseudo-random pattern is generated in the shift-register elements of the BSCs on each rising edge of TCK
and then updated in the shadow latches and applied to the device output terminals on each falling edge of TCK.
This data also is updated in the shadow latches of the input BSCs and applied to the inputs of the normal on-chip
logic. Figure 5 illustrates the 16-bit linear-feedback shift-register algorithm through which the patterns are
generated. An initial seed value should be scanned into the BSR before performing this operation. A seed value
of all zeroes will not produce additional patterns.
1D
2D
3D
4D
5D
6D
7D
8D
=
1Q
2Q
3Q
4Q
5Q
6Q
7Q
8Q
Figure 5. 16-Bit PRPG Configuration
parallel-signature analysis (PSA)
Data appearing at the device input terminals is compressed into a 16-bit parallel signature in the shift-register
elements of the BSCs on each rising edge of TCK. This data is then updated in the shadow latches of the input
BSCs and applied to the inputs of the normal on-chip logic. Data in the shadow latches of the output BSCs
remains constant and is applied to the device outputs. Figure 6 illustrates the 16-bit linear-feedback shift-register
algorithm through which the signature is generated. An initial seed value should be scanned into the BSR before
performing this operation.
1D
2D
3D
4D
5D
6D
7D
8D
=
=
1Q
2Q
3Q
4Q
5Q
6Q
7Q
8Q
Figure 6. 16-Bit PSA Configuration
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