Datasheet

SN54ABTH18502A, SN54ABTH182502A, SN74ABTH18502A, SN74ABTH182502A
SCAN TEST DEVICES
WITH 18-BIT UNIVERSAL BUS TRANSCEIVERS
SCBS164E – AUGUST 1993 – REVISED DECEMBER 1996
18
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
parallel-signature analysis (PSA)
Data appearing at the selected device input-mode I/O pins is compressed into a 36-bit parallel signature in the
shift-register elements of the selected BSCs on each rising edge of TCK. Data in the shadow latches of the
selected output-mode BSCs remains constant and is applied to the associated device I/O pins. Figures 7 and 8
illustrate the 36-bit linear-feedback shift-register algorithms through which the signature is generated. An initial
seed value should be scanned into the BSR before performing this operation.
=
1B8-I/O 1B7-I/O 1B6-I/O 1B5-I/O 1B4-I/O 1B3-I/O 1B2-I/O 1B1-I/O1B9-I/O
1A7-I/O 1A6-I/O 1A5-I/O 1A4-I/O 1A3-I/O 1A2-I/O 1A1-I/O1A8-I/O1A9-I/O
2A7-I/O 2A6-I/O 2A5-I/O 2A4-I/O 2A3-I/O 2A2-I/O 2A1-I/O2A8-I/O2A9-I/O
2B8-I/O 2B7-I/O 2B6-I/O 2B5-I/O 2B4-I/O 2B3-I/O 2B2-I/O 2B1-I/O2B9-I/O
=
Figure 7. 36-Bit PSA Configuration (1OEAB = 2OEAB = 0, 1OEBA = 2OEBA = 1)