UCC5617
DESCRIPTION
The UCC5617 provides 18 lines of active termination for a SCSI (Small
Computers Systems Interface) parallel bus. The SCSI standard recom-
mends and Fast-20 (Ultra) requires active termination at both ends of the
cable.
Pin for pin compatible with the UC5609, the UCC5617 is ideal for high per-
formance 5V SCSI systems, Termpwr 4.0-5.25V. During disconnect the
supply current is only 50 A typical, which makes the IC attractive for lower
powered systems.
The UCC5617 is designed with a low channel capacitance of 2pF, which
eliminates effects on signal integrity from disconnected terminators at in-
terim points on the bus.
The power amplifier output stage allows the UCC5617 to source full termi-
nation current and sink active negation current when all termination lines
are actively negated.
The UCC5617, as with all Unitrode terminators, is completely hot pluggable
and appears as high impedance at the terminating channels with
TRMPWR = 0V or open.
Internal circuit trimming is utilized, first to trim the 110
impedance, and
then most importantly, to trim the output current as close to the maximum
SCSI-3 specification as possible, which maximizes noise margin in fast
SCSI operation.
This device is offered in low thermal resistance versions of the industry
standard 28 pin wide body SOIC.
18-Line SCSI Terminator (Reverse Disconnect)
FEATURES
Complies with SCSI, SCSI-2, SCSI-3,
SPI and FAST-20 Standards
2pF Channel Capacitance During
Disconnect
50mA Supply Current in Disconnect
Mode
110 Termination
SCSI Hot Plugging Compliant, 10nA
Typical
+400mA Sinking Current for Active
Negation
650mA Sourcing Current for
Termination
Trimmed Impedance to 5%
Thermal Shutdown
Current Limit
SLUS351A - APRIL 1997 - REVISED AUGUST 2002
BLOCK DIAGRAM
UDG-96073
Patented Circuit Design
2
UCC5617
ABSOLUTE MAXIMUM RATINGS
TEMPWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A
Storage Temperature . . . . . . . . . . . . . . . . . . . 65C to +150C
Operating Junction Temperature . . . . . . . . . . 55C to +150C
Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300C
All currents are positive into, negative out of the specified
terminal. Consult Packaging Section of Databook for thermal
limitations and considerations of packages.
* DWP package pin 28 serves as signal ground; pins 7, 8, 9,
20, 21, 22 serve as heatsink/ground.
CONNECTION DIAGRAMS
SOIC-28 (Top View)
DWP Package
3
UCC5617
ELECTRICAL CHARACTERISTICS:
Unless otherwise stated these specifications apply for T
A
= 0C to 70C,
TRMPWR = 4.75V, DISCNCT = 0V, T
A
= T
J
.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current Section
TERMPWR Supply Current
All Termination Lines = Open
1
2
mA
All Termination Lines = 0.2V
420
440
mA
Power Down Mode
DISCNCT = 0V
50
100
A
Output Section (Termination Lines)
Termination Impedance
(Note 3)
104.5
110
115.5
Output High Voltage
V
TRMPWR
= 4V (Note 1)
2.6
2.8
3
V
Max Output Current
V
LINE
= 0.2V, T
J
= 25C
22.1
23.3
24
mA
V
LINE
= 0.2V
20.7
23.3
24
mA
V
LINE
= 0.2V, TERMPWR = 4V, T
J
= 25C
(Note 1)
21
23.3
24
mA
V
LINE
= 0.2V, TRMPWR = 4V (Note 1)
20
23
24
mA
V
LINE
= 0.5V
22.4
mA
Output Leakage
DISCNCT = 2.4V, TRMPWR = 0V to 5.25V,
REG = 0.2V, V
LINE
= 5.25V
10
400
nA
Output Capacitance
DISCNCT = 2.4V (Note 2)
2
3.5
pF
Regulator Section
Regulator Output Voltage
2.6
2.8
3
V
Drop Out Voltage
All Termination Lines = 0.2V
0.4
0.8
V
Short Circuit Current
V
REG
= 0V
475
650
850
mA
Sinking Current Capability
V
REG
= 3.5V
200
400
800
mA
Thermal Shutdown
170
C
Thermal Shutdown Hysteresis
10
C
Disconnect Section
Disconnect Threshold
0.8
1.5
2
V
Input Current
DISCNCT = 0V
10
30
A
Note 1: Measuring each termination line while other 17 are low (0.2V).
Note 2: Guaranteed by design. Not 100% tested in production.
Note 3: Tested by measuring I
OUT
with V
OUT
= 0.2V and V
OUT
with no load, then calculating: Z
V
N L
V
I
at
V
OUT
OUT
=
. . .
.
0 2
0 2
PIN DESCRIPTIONS
DISCNCT: Taking this pin low causes the 18 channels to
become high impedance and the chip to go into
low-power mode; a high or open state allows the
channels to provide normal termination.
GND: Ground reference for the IC.
LINE1LINE18: 110
termination channels.
REG: Output of the internal 2.8V regulator.
TRMPWR: Power for the IC.
4
UCC5617
UDG-96074
Figure 1. Termline Impedance Measurement Circuit
APPLICATION INFORMATION
Procedure:
1) Measure V
REG
N.L.
2) Set V
L
= 0.2V
3) Measure I
MAX
at 0.2V
4) Impedance =
V
N L
V
I
REG
MAX
. . .
0 2
UDG-96108
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