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SLUS349B − DECEMBER 1994 − REVISED APRIL 2005
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FEATURES
DComplies with SCSI, SCSI−2 and SPI−2 Single
Ended Standards
D2.7-V to 5.25-V Operation
D1.8-pF Channel Capacitance during
Disconnect
D0.5-µA Supply Current in Disconnect Mode
D110-Ω/2.5-kΩ Programmable Termination
DCompletely Meets SCSI Hot Plugging
D−400-mA Sourcing Current for Termination
D+400-mA Sinking Current for Active Negation
Drivers
DTrimmed Termination Current to 4%
DTrimmed Impedance to 7%
DCurrent Limit and Thermal Shutdown
Protection
DESCRIPTION
The UCC5614 provides 9 lines of active termination for
a small computer system’s interface (SCSI) parallel
bus. The SCSI standard recommends active
termination at both ends of the cable segment.
The UCC5614 is ideal for high performance 3.3-V SCSI
systems. The key features contributing to such low
operating voltage are the 0.1-V drop-out regulator and
the 2.7-V reference. During disconnect the supply
current is typically only 0.5 µA, which makes the device
attractive for battery powered systems.
The UCC5614 is designed with an ultra low channel
capacitance o f 1.8 pF, which eliminates effects on signal
integrity from disconnected terminators at interim points
on the bus.
BLOCK DIAGRAM
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Copyright 2005, Texas Instruments Incorporated
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SLUS349B − DECEMBER 1994 − REVISED APRIL 2005
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DESCRIPTION (CONTINUED)
The UCC5614 can be programmed for either a 110-Ω or 2.5-kΩ termination. The 110-Ω termination is used for
standard SCSI bus lengths and the 2.5-kΩ termination is typically used in short bus applications. When driving
the TTL compatible DISCNCT pin directly, the 110-Ω 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
80 kΩ and 150 kΩ, the terminator is in short bus mode. The 2.5-kΩ termination is connected when the DISCNCT
pin is driven low and disconnected when driven high.
The power amplifier output stage allows the UCC5614 to source full termination current and sink active negation
current when all termination lines are actively negated.
The UCC5614 is pin for pin compatible with Unitrode’s other 9-line SCSI terminators, allowing lower capacitance
and lower voltage upgrades to existing systems. The UCC5614, as with all Unitrode terminators, is completely
hot pluggable and appears as high impedance at the terminating channels with VTRMPWR = 0 V or open.
Internal circuit trimming is utilized, first to trim the 110-Ω 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 specification as possible,
which maximizes noise margin in fast SCSI operation.
Other features include thermal shutdown and current limit.
This device is offered in low thermal resistance versions of the industry standard 16-pin narrow body SOIC,
16-pin N and 24-pin TSSOP.
ORDERING INFORMATION
TA
PACKAGED DEVICE
T
ASOIC-16 (DP){DIL-16 (N) TSSOP-24 (PW)}
0°C to 70°C UCC5614DP UCC5614N UCC5614PW
††The DP package is available taped and reeled in quanities of 2,500. Add TR suffix to device type (e.g. UCC5614DPTR) to order quantities of
2,500 devices per reel.
‡The PW package is available taped and reeled in quanities of 2,000. Add TR suffix to device type (e.g. UCC5614PWTR) to order quantities of
2,000 devices per reel.
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SLUS349B − DECEMBER 1994 − REVISED APRIL 2005
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CONNECTION DIAGRAMS
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
LINE7
LINE8
LINE9
GND
SGND
D
ISCNCT
LINE1
LINE2
LINE6
LINE5
REG
GND
GND
TRMPWR
LINE4
LINE3
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
LINE7
LINE8
LINE9
N/C
SGND
DISCNCT
LINE1
LINE2
LINE6
LINE5
REG
N/C
N/C
TRMPWR
LINE4
LINE3
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
LINE7
LINE8
LINE9
N/C
SGND
GND
GND
GND
GND
DISCNCT
LINE1
LINE2
LINE6
LINE5
REG
REG
GND
GND
GND
GND
TRMPWR
TRMPWR
LINE4
LINE3
SOIC−16 (Top View)
DP Package (1) (2)
DIL−16 (Top View)
N Package (1)
TSSOP−24 (Top View)
PW Package (1) (3)
NOTES: (1). Drawings are not to scale.
(2). DP package pin 5 serves as ground and pins 4,12 and 13 serve as heatsink ground.
(3). PW package pin 5 serves as ground and pins 6,7,8,9,17,18,19 and 20 serve as heatsink ground.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted{}
UCC5629 UNIT
TRMPWR voltage 6
V
Input voltage 0 to 7 V
Regulator output current 2 W
Storage temperature, Tstg −65 to 150
Operating junction temperature, TJ–55 to 150 °C
Lead temperature (soldering, 10 sec.) 300
C
†Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is
not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect
to GND. Currents are positive into and negative out of, the specified terminal.
‡Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and
considerations of packages. All voltages are referenced to GND.
RECOMMENDED OPERATING CONDITIONS
MIN NOM MAX UNIT
TRMPWR voltage 2.7 5.25 V
Temperature ranges 0 70 °C
Signal line voltage 0 5
V
DISCNCT input voltage 0 TRMPWR V
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SLUS349B − DECEMBER 1994 − REVISED APRIL 2005
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ELECTRICAL CHARACTERISTICS
TA = 0 °C to 70°C, TRMPWR = 3.3 V, DISCNCT = 0 V, RDISCNCT = 0 Ω, TA = TJ, (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Supply Current Section
Termpwr supply current
All termination lines = Open 1 2
mA
Termpwr supply current All termination lines = 0.2 V 210 218 mA
Power down mode DISCNCT = Trmpwr 0.5 5 µA
Output Section (110 Ω − Terminator Lines)
Terminator impedance 102.3 110 117.7 Ohms
Output high voltage (Note 1) 2.5 2.7 3.0 V
VLINE = 0.2 V TJ = 25°C −22.1 −23 −24
VLINE = 0.2 V −21 −23 −24
Max output current VLINE = 0.2 , TRMPWR = 3 V, TJ = 25°C (Note
1) −20.2 −23 −24 mA
VLINE = 0.2 V, TRMPWR = 3 V (Note 1) −19 −23 −24
VLINE = 0.5 V −22.4
Output leakage DISCNCT = 2.4 V, TRMPWR = 0 V to 5.25 V 10 400 nA
Output capacitance DISCNCT = 2.4 V (Note 2) (DP Package) 1.8 2.5 pF
Output Section (2.5 kΩ − Terminator Lines) (RDISCNCT = 80 kΩ)
Terminator impedance 2 2.5 3 kΩ
Output high voltage TRMPWR = 3 V (Note 1) 2.5 2.7 3.0 V
Max output current VLINE = 0.2 V −0.7 −1 −1.4
mA
VLINE = 0.2 V, TRMPWR = 3 V (Note 1) −0.6 −1 −1.5 mA
Output leakage DISCNCT = 2.4 V, TRMPWR = 0 to 5.25 V 10 400 nA
Output capacitance DISCNCT = 2.4 V (Note 2) (DP Package) 1.8 2.5 pF
Regulator Section
Regulator output voltage 5.25 V > TRMPWR > 3 V 2.5 2.7 3.0
V
Drop out voltage All Termination Lines = 0.2 V 0.1 0.2 V
Short circuit current VREG = 0 V −200 −400 −800
mA
Sinking current capability VREG = 3 V 200 400 800 mA
Thermal shutdown (Note 2) 170
°C
Thermal shutdown hysteresis (Note 2) 10 °C
Disconnect Section
Disconnect threshold RDISCNCT = 0 & 80 kΩ0.8 1.5 2.0 V
Input current DISCNCT = 0 V 30 50 mA
NOTES: 1. Measuring each termination line while other eight are low (0.2 V).
2. Ensured by design. Not production tested.
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SLUS349B − DECEMBER 1994 − REVISED APRIL 2005
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Terminal Functions
TERMINAL
I/O
DESCRIPTION
NAME NO.
I/O
DESCRIPTION
DISCNCT 7 I Taking this pin high causes the 9 channels to become high impedance and the chip to go into low
power mode. In short laptop buses an 80-kΩ to 150-kΩ resister to ground terminates the bus at 2.5
kΩ. Less than 110 Ω to ground enables the terminator.
GND 9 Ground reference for the device
LINE1 TO
LINE9 4 I 110-Ω termination channels
REG 9 o Output of the internal 2.7-V regulator
TRMPWR 4 I Power for the device
APPLICATION INFORMATION
Figure 1. Typical SCSI Bus Configuration Utilizing two UCC5614 Devices
Figure 2. Typical Wide SCSI Bus Configuration Utilizing three UCC5614 Devices
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