UCC5641
SLUS397 - JANUARY 2000
FEATURES
•
First LVD only Active Terminator
•
Meets SCSI SPI-2 Ultra2 (Fast-40)
and Ultra3 / Ultra160 (Fast-80)
Standards
•
2.7V to 5.25V Operation
•
Differential Failsafe Bias
•
Reversed Disconnect Polarity
Low Voltage Differential (LVD) SCSI 9 Line Terminator
REF 1.25V
15DISCNCT
27 LVD*
1
REG
11
DIFFB
4
L1–
3
L1+
26 L9–
25 L9+
56mV
SOURCE/SINK REGULATOR
REF 1.3V
1.3V ± 0.1V
0.7V > 0.5V
2.4V > 1.9V
HIGH IMPEDANCE RECEIVER
EVEN WITH POWER OFF
SINGLE
ENDED
HIGH POWER
DIFFERENTIAL
12
DIFSENS
SOURCE 5–15mA
SINK 200µAMAXIMUM(NOISELOAD)
OPEN CIRCUIT ON POWER OFF
OR OPEN CIRCUIT IN A
DISABLED TERMINATOR MODE
10µA
28TRMPWR
LOW
FREQUENCY
FILTER
50Hz – 60Hz
20k
124
124
52
52
52
52
4.7µF
0.1µF
14
GND
SOURCE ONLY FROM TRMPWR AND THE ENABLED TERMINATIONS
2.7V to 5.25V
56mV
+–
–+
56mV
+–
56mV
–+
BLOCK DIAGRAM
UDG-99160
DESCRIPTION
The UCC5641 is an active terminator for Low Voltage Differential (LVD)
SCSI networks. This LVD only design allows the user to reach peak bus
performance while reducing system cost. The device is designed as an
active Y-terminator to improve the frequency response of the LVD Bus.
Designed with a 1.5pF channel capacitance, the UCC5641 allows for mini
mal bus loading for a maximum number of peripherals. With the
UCC5641, the designer will be able to comply with the Fast-40 SPI-2 and
Fast-80 SPI-3 specifications. The UCC5641 also provides a much-needed
system migration path for ever improving SCSI system standards. This de
vice is available in the 24 pin TSSOP and 28 pin TSSOP for ease of lay
out use.
The UCC5641 is not designed for use in single ended or high voltage dif
ferential systems.
* 28 pin package only
2
UCC5641
ABSOLUTE MAXIMUM RATINGS
TERMPWR Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to 3.6V
Package Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1W
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
Currents are positive into negative out of the specified terminal.
consult Packaging Section of Databook for thermal limitations
and considerations of package.
RECOMMENDED OPERATING CONDITIONS
TERMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.25V
DIFFB
L6+
L8–
L8+
L7–
TRMPWR
L1+
L4–
L3+
L4+
L1–
L2+
L2–
REG
L3–
DIFSENS
L7+
L6–
L5–
12
11
10
9
8
7
6
5
4
3
2
1
13
14
15
16
17
18
19
20
21
22
23
24
L5+
L9–
L9+
GND DISCNCT
CONNECTION DIAGRAMS
TSSOP-24 (Top View)
PW24 Package
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, specifications apply for T
A
= 0°C to 70°C,
TRMPWR = 3.3V. T
A=TJ
.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
TRMPWR Supply Current Section
TRMPWR Supply Current No Load 25 mA
Disabled Terminator 400 µA
TRMPWR Voltage 2.7 5.25 V
DIFFB
L6+
L8–
L8+
L7–
TRMPWR
L1+
N/C
L4–
L3+
L4+
L1–
L2+
L2–
REG
L3–
DIFSENS
L7+
L6–
L5–
N/C
GND
14
13
12
11
10
9
8
7
6
5
4
3
2
1
15
16
17
18
19
20
21
22
23
24
25
26
27
28
L5+
N/C
DISCNCT
L9–
L9+
LV D
TSSOP-28 (Top View)
PW28 Package
3
UCC5641
ELECTRICAL CHARACTERISTICS:
Unless otherwise stated, specifications apply for TA= 0°C to 70°C,
TRMPWR = 3.3V. T
A=TJ
.
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Regulator Section
1.25V Regulator DIFSENS connected to DIFFB 1.15 1.25 1.35 V
1.25V Regulator Source Current DIFSENS connected to DIFFB –100 –80 mA
1.25V Regulator Sink Current DIFSENS connected to DIFFB 80 100 mA
1.3V Regulator DIFFB connected to GND 1.2 1.3 1.4 V
1.3V Regulator Source Current DIFSENS to GND –15 –5 mA
1.3V Sink Current DIFSENS to 3.3V 50 200 µA
Differential Termination Section
Differential Impedance –2.5mA to 4.5mA 100 105 110 Ω
Common Mode Impedance L+ connected to L– 110 150 165 Ω
Differential Bias Voltage No load, L+ or L– 100 125 mV
Common Mode Bias 1.15 1.25 1.35 V
Output Leakage, Disconnect DISCNCT
, TRMPWR = 0 to 5.25V,
V
LINE
= 0.2 to 5.25V
10 400 nA
Output Capacitance Single ended measurement to ground (Note 1) 3 pF
Low Voltage Differential (LVD) Status Bit Section
I
SOURCE
V
LOAD
= 2.4V –6 –4 mA
I
SINK
V
LOAD
= 0.4V 2 5 mA
Disconnect & Differential Sense Input Section
DISCNCT
Threshold 0.8 2 V
Input Current At 0V and 3.3V –30 –10 µA
Differential Sense SE to LVD Threshold 0.5 0.7 V
Differential Sense LVD to HPD Threshold 1.9 2.4 V
Note 1: Guaranteed by design. Not 100% tested in production.
PIN DESCRIPTION
DIFFB: Differential sense filter pin should be connected
to a 0.1µF capacitor and 20k
resistor to Diff Sense.
DIFSENS: The SCSI bus differential sense line to detect
what type of devices are connected to the SCSI Bus.
DISCNCT
: Disconnect pin shuts down the terminator
when it is not at the end of the bus.
GND: Ground.
L
n
–: Negative line in differential applications for the
SCSI Bus.
L
n
+: Positive line for differential applications for the
SCSI Bus.
LVD: (28 pin package only) Indicates that the bus is in
LVD mode.
REG: Regulator bypass; must be connected to a 4.7
F
capacitor to ground.
TRMPWR: V
IN
2.7V to 5.25V supply.
4
UCC5641
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
REG
TRMPWR
DISCNCT
TRMPWR
DIFFB REG
Te r m p ow e r
Te r m p ow e r
28
15
12
1 11
11
1
24
DISCNCT 13
CONTROL LINES (9)
20k20k
DIFF SENSE
3 2
4 3
4.7µF
0.1µF
25 22
26 23
L1+
L1–
L9+
L9–
L1+
L1–
L9+
L9–
4.7µF
DIFFB
10
0.1µF
REG
TRMPWR
DISCNCT
TRMPWR
DIFFB REG
28
15
1 11 1
24
DISCNCT 13
DATA LINES (9)
3 2
4 3
4.7µF
25 22
26 23
L1+
L1–
L9+
L9–
L1+
L1–
L9+
L9–
4.7µF
DIFFB
10
REG
TRMPWR
DISCNCT
TRMPWR
DIFFB REG
28
15
1 11 1
24
DISCNCT
13
DATA LINES (9)
3 2
4 3
4.7µF
25 22
26 23
L1+
L1–
L9+
L9–
L1+
L1–
L9+
L9–
4.7µF
DIFFB
10
4.7µF
4.7µF
UCC5641PW28 UCC5641PW24
UCC5641PW24UCC5641PW28
UCC5641PW24UCC5641PW28
27 LVD
S2*
S1*
* CLOSE S1 AND S2 TO DISABLE TERMINATORS
Figure 1. Application diagram.
APPLICATION INFORMATION
UDG-99159
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