Datasheet
SN54ABT8543, SN74ABT8543
SCAN TEST DEVICES WITH
OCTAL REGISTERED BUS TRANSCEIVERS
SCBS120E – AUGUST 1991 – REVISED JULY 1996
13
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
pseudo-random pattern generation (PRPG)
A pseudo-random pattern is generated in the shift-register elements of the selected BSCs on each rising edge
of TCK, updated in the shadow latches, and applied to the associated device output pins on each falling edge
of TCK. This data also is updated in the shadow latches of the selected input BSCs and applied to the inputs
of the normal on-chip logic. Figures 4 and 5 show the 16-bit linear-feedback shift-register algorithms 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 does not produce additional patterns.
=
A8-I
B8-O
A7-I A6-I A5-I A4-I A3-I A2-I A1-I
B7-O B6-O B5-O B4-O B3-O B2-O B1-O
Figure 4. 16-Bit PRPG Configuration (OEA = 0, OEB = 1)
=
B8-I
A8-O
B7-I B6-I B5-I B4-I B3-I B2-I B1-I
A7-O A6-O A5-O A4-O A3-O A2-O A1-O
Figure 5. 16-Bit PRPG Configuration (OEA=1, OEB= 0)