18-Line SCSI Terminator (Reverse Disconnect)
UCC5617
FEATURES
Complies with SCSI, SCSI-2, SCSI-3,
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SPI and FAST-20 Standards
2pF Channel Capacitance During
•
Disconnect
50mA Supply Current in Disconnect
•
Mode
110
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•
•
•
• Trimmed Impedance to 5%
• Thermal Shutdown
• Current Limit
Termination
SCSI Hot Plugging Compliant, 10nA
Typical
+400mA Sinking Current for Active
Negation
–650mA Sourcing Current for
Termination
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
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
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.
A typical, which makes the IC attractive for lower
impedance, and
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BLOCK DIAGRAM
This device is offered in low thermal resistance versions of the industry
standard 28 pin wide body SOIC.
Patented Circuit Design
SLUS351A - APRIL 1997 - REVISED AUGUST 2002
UDG-96073
UCC5617
CONNECTION DIAGRAMS
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.
ABSOLUTE MAXIMUM RATINGS
TEMPWR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Operating Junction Temperature . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C
All currents are positive into, negative out of the specified
terminal. Consult Packaging Section of Databook for thermal
limitations and considerations of packages.
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