Datasheet

5
UCC5672
nation for the bus as follows. If the DIFSENS signal is
below 0.5V, the termination network is set for single
ended. Between 0.7V and 1.9V, the termination network
switches to LVD SCSI, and above 2.4V indicates HVD
SCSI, causing the terminators to disconnect from the
bus. These thresholds accommodate differences in
ground potential that can occur with long lines.
Three UCC5672 multi-mode parts are required at each
end of the bus to terminate 27 (18 data, plus 9 control)
lines. Each part includes a DIFSENS driver, but only one
is necessary to drive the line. The DIFFB inputs on all
three parts are connected together, allowing them to
share the same 50Hz noise filter. This multi-mode termi
-
nator operates in full specification down to 2.7V
TRMPWR voltage. This accommodates 3.3V systems,
APPLICATION INFORMATION (cont.)
REG DIFFB
16
1 17
16
CONTROL LINES (9)
20 k20 k
DIFF SENSE
4 2
5 3
4.7 F
0.1 µF
31 25
32 26
L1+
L1–
L9+
L9–
L1+
L1–
L9+
L9–
DIFFS
UCC5672
UCC5672
DIFFS
REGDIFFB
117
4.7 F
0.1 µF
REG DIFFB
1 17
DATA LINES (9)
4 2
5 3
4.7 F
31 25
32 26
L1+
L1–
L9+
L9–
L1+
L1–
L9+
L9–
UCC5672
UCC5672
REGDIFFB
117
4.7 F
REG
TRMPWR
DIFFB
28
1 17
DATA LINES (9)
2 2
3 3
4.7 F
25 25
26 26
L1+
L1–
L9+
L9–
L1+
L1–
L9+
L9–
UCC5672
UCC5672
27 TRMPWR
13 DISCNCT
REGDIFFB
117
4.7 F
TRMPWR28
27 TRMPWR
13 DISCNCT
TRMPWR
28
27 TRMPWR
13 DISCNCT
28
27
13
TRMPWR
TRMPWR
DISCNCT
28
27
13
TRMPWR
TRMPWR
DISCNCT
28
27
13
TRMPWR
TRMPWR
DISCNCT
16 NC
16 NCNC 16
NC
16
4.7 F
4.7 F
Termpower
Termpower
Figure 1. Application diagram.
Note: Indicated pinout is for 28 pin TSSOP package.
UDG-99126