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