ETC UCC5610N

UCC5610
18-Line 3-5 Volt Low Capacitance SCSI Active Terminator
FEATURES
DESCRIPTION
•
Complies with SCSI, SCSI-2, SCSI-3
and FAST-20 (Ultra) Standards
•
2.75V to 7V Operation
The UCC5610 provides 18 lines of active termination for a SCSI (Small
Computer Systems Interface) parallel bus. The SCSI standard recommends active termination at both ends of the cable.
•
1.8pF Channel Capacitance during
Disconnect
•
0.5µA Supply Current in Disconnect
Mode
•
110 Ohm/2.5k Programmable
Termination
•
Completely Meets SCSI Hot Plugging
•
-650mA Sourcing Current for
Termination
•
+400mA Sinking Current for Active
Negation Drivers
•
Trimmed Termination Current to 4%
•
Trimmed Impedance to 7%
•
Current Limit and Thermal Shutdown
Protection
The UCC5610 is ideal for high performance 3.3V SCSI systems. The key
features contributing to such low operating voltage are the 0.1V drop out
regulator and the 2.75V reference. The reduced reference voltage was
necessary to accommodate the lower termination current dictated in the
SCSI-3 specification. During disconnect the supply current is typically
only 0.5µA, which makes the IC attractive for battery powered systems.
The UCC5610 is designed with an ultra low channel capacitance of
1.8pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus.
The UCC5610 can be programmed for either a 110 ohm or 2.5k ohm termination. The 110 ohm termination is used for standard SCSI bus lengths
and the 2.5k ohm termination is typically used in short bus applications.
When driving the TTL compatible DISCNCT pin directly, the 110 ohm termination is connected when the DISCNCT pin is driven low, and disconnected when driven high. When the DISCNCT pin is driven through an
impedance between 80k and 150k, the 2.5k ohm termination is connected when the DISCNCT pin is driven low, and disconnected when
driven high.
continued
BLOCK DIAGRAM
UDG-94128-1
Circuit Design Patented
2/97
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UCC5610
Description Continued
ohm termination impedance to a 7% tolerance, and then
most importantly, to trim the output current to a 4% tolerance, as close to the max SCSI-3 spec as possible,
which maximizes noise margin in FAST-20 SCSI operation.
The power amplifier output stage allows the UCC5610 to
source full termination current and sink active negation
current when all termination lines are actively negated.
The UCC5610 is pin for pin compatible with Unitrode’s
other 18 line SCSI terminators, allowing lower capacitance and lower voltage upgrades to existing systems.
The UCC5610, as with all Unitrode terminators, is completely hot pluggable and appears as high impedance at
the terminating channels with VTRMPWR = 0V or open.
Other features include thermal shutdown and current
limit.
Internal circuit trimming is utilized, first to trim the 110
This device is offered in low thermal resistance versions
of the industry standard 28 pin wide body SOIC, 24 pin
wide body DIP and 28 pin PLCC.
ABSOLUTE MAXIMUM RATINGS
CONNECTION DIAGRAMS
Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . Self-regulating
Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Operating Temperature . . . . . . . . . . . . . . . . . −55°C to +150°C
Lead Temperature (Soldering, 10 Sec.) . . . . . . . . . . . . . +300°C
Unless otherwise specified all voltages are with respect to
Ground. Currents are positive into, negative out of the specified terminal.
Consult Packaging Section of Unitrode Integrated Circuits databook for thermal limitations and considerations of packages.
PLCC-28 (Top View)
QP Package
RECOMMENDED OPERATING CONDITIONS
Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . 2.75V to 5.25V
Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V
Disconnect Input Voltage . . . . . . . . . . . . . . . . . . 0V to Termpwr
* QP package pins 12 - 18 serve as both heatsink and signal
ground.
DIL-24 (Top View)
N or J Package
SOIC-28 (Top View)
DWP Package
* DWP package pin 28 serves as signal ground; pins 7, 8, 9,
20, 21, 22 serve as heatsink/ground.
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Note: Drawings are not to scale.
2
UCC5610
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 0°C to 70°C.
TRMPWR = 3.3V, DISCNCT = 0V, RDISCNCT= 0 ohms. TA = TJ.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current Section
Termpwr Supply Current
Power Down Mode
All termination lines = Open
1
2
mA
All termination lines = 0.2V
415
455
mA
DISCNCT = Termpwr
0.5
5
µA
Output Section (110 ohms - Terminator Lines)
Terminator Impedance
(Note 4)
102.3
110
117.7
Ohms
Output High Voltage
(Note 1)
2.5
2.7
3.0
V
Max Output Current
VLINE = 0.2V, TJ = 25°C
VLINE = 0.2V
VLINE = 0.2V, TRMPWR = 3V, TJ = 25°C (Note 1)
VLINE = 0.2V, TRMPWR = 3V (Note 1)
−22.1
−23
−24
mA
−21
−23
−24
mA
−20.2
−23
−24
mA
−19
−23
−24
mA
−22.4
mA
Output Leakage
DISCNCT = 2.4V, TRMPWR = 0V to 5.25V
10
400
nA
Output Capacitance
DISCNCT = 2.4V (Note 2, 3) (DWP Package)
1.8
2.5
pF
kΩ
VLINE = 0.5V
Output Section (2.5k ohms - Terminator Lines) (RDISCNCT = 80k ohms)
Terminator Impedance
2
2.5
3
Output High Voltage
TRMPWR = 3V (Note 1)
2.5
2.7
3.0
V
Max Output Current
VLINE = 0.2V
−0.7
−1
−1.4
mA
VLINE = 0.2V, TRMPWR = 3V (Note 1)
−0.6
−1
−1.5
mA
Output Leakage
DISCNCT = 2.4V, TRMPWR = 0 to 5.25V
10
400
nA
Output Capacitance
DISCNCT = 2.4V (Note 2, 3) (DWP Package)
1.8
2.5
pF
Regulator Section
Regulator Output Voltage
5.25V > TRMPWR > 3V
Drop Out Voltage
All Termination Lines = 0.2V
2.5
2.7
3.0
V
0.1
0.2
V
Short Circuit Current
VREG = 0V
−450
−650
−800
mA
Sinking Current Capability
VREG = 3V
200
400
800
mA
Thermal Shutdown
(Note 2)
170
°C
Thermal Shutdown Hysteresis
(Note 2)
10
°C
Disconnect Section
Disconnect Threshold
RDISCNCT = 0 & 80k
Input Current
DISCNCT = 0V
Note 1:
Note 2:
Note 3:
Note 4:
0.8
Measuring each termination line while other 17 are low (0.2V).
Guaranteed by design. Not 100% tested in production.
Output capacitance is measured at 0.5V.
Tested by measuring IOUT with VOUT = 0.2V and VOUT = VREG - 0.1V then calculating the impedance.
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3
1.5
2.0
V
30
50
µA
UCC5610
APPLICATION INFORMATION
UDG-94130
Figure 1: Typical SCSI Bus Configurations Utilizing A UCC5610 Device
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
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4
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