• Reverse Disconnect
• Complies with SCSI, SCSI-2 and SPI-2
Standards
• 6pF Channel Capacitance during
Disconnect
• 100µA Supply Current in Disconnect
Mode
• Meets SCSI Hot Plugging Capability
•−650mA Sourcing Current for
Termination
• +200mA Sinking Current for Active
Negation
• Provides Active Termination for 18 Lines
• Logic Command Disconnects all
Termination Lines
• Trimmed Termination Current to 5%
• Trimmed Impedance to 5%
• Current Limit and Thermal Shutdown
Protection
The UC5609 provi des 18 lines of active termination for a SCSI (Small
Computer Sy s t em s I nt er f ac e ) par all el bus. The SCS I s tandard recommends active termination at both ends of the bus cable.
The UC5609 is pin-for-pin compatible with its predecessors, the
UC5601, UC 5602 and UC5608 - 18 Lin e Active Terminators, except
for the r everse disconnect sense. Parametrica lly the UC5609 has a
5% tolerance on impedan ce and curre nt compared to a 3% tolerance
on the UC56 01 and the si nk current i s increased from 20 to 200mA.
The low sid e clamps have been re moved. Custom power pac kages
are utilized to allow normal operation at full power conditions (2
Watts).
When in disconnect mode the terminator will disconnect all terminating resistors and disable the regulator, greatly reducing standby
power. The output channels remain high impedance even without
Termpwr applied.
Internal circuit trimming is utilized to tri m the impedance to a 5% tolerance and, most importantly, to trim the outp ut current to a 5% tolerance, as c lose to the max SCSI spec as possible, which maximizes
noise margin in fast SCSI operation.
Other feat ures include 4.0 to 5.25V Termpwr, thermal shutdown and
current limit.
This device is offered in low the rmal re sistance v ersions of the industry standard 28 pin wide body SOIC, 28 pin wide body TSSOP, and 28
pin PLCC, as well as 24 pin DIP.
UC5609
18-Line Low Capacitance SCSI Active Terminator
FEATURES DESCRIPTION
BLOCK DIAGRAM
Circuit Design Patented
4/97
UDG-94126
* PWP package pin 23 serves as signal ground; pins 7, 8, 9,
20, 21 and 22 serve as heats in k/ gro un d.
TSSOP-28 (To p View)
PWP Package
ABSOLUTE MAXIMUM RATINGS
Termpwr Vo ltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −55°C to +150°C
Lead Temperature (Soldering, 10 Sec.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C
RECOMMENDED OPERATING CONDITIONS
Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8V to 5.25V
Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V
Disconnect Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to Termpwr
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 consid era ti on s of pac ka ges.
UC5609
CONNECTION DIAGRAMS
PLCC-28 (Top View)
QP Package
* QP package pins 12 - 18 serve as both heatsink and signal
ground.
* DWP package pin 28 serves as signal ground; pins 7, 8, 9,
20, 21, 22 serve as heatsink/ground.
SOIC-28 (Top View)
DWP Package
Note: Drawings are not to scale.
DIL-24 (Top View)
N or J Package
2
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Supply Current Section
Termpwr Supply Current All termination lines = Open 17 25 mA
All termination li ne s = 0. 5V 400 430 mA
Power Down Mode DISCNCT = GND 100 150 µA
Output Section (Termina tor Li ne s)
Terminator Impedance ∆I
LINE
= -5mA to -15mA 104.5 110 115.5 Ω
Output High Voltage V
TRMPWR
= 4V (Note 1) 2.65 2.9 3.0 V
Max Output Cur r e nt V
LINE
= 0.5V TJ = 25°C -20.3 -21.5 -22.4 mA
0°C < T
J
< 70°C -19.8 -21.5 -22.4 mA
Max Output Cur r e nt V
LINE
= 0.5V, TRMPWR = 4V (Note 1) TJ = 25°C -19.5 -21.5 -22.4 mA
0°C < T
J
< 70°C -19.0 -21.5 -22.4 mA
V
LINE
= 0.2V, TRMPWR = 4V to 5.25V 0°C < TJ < 70°C -21.6 -24.0 -25.4 mA
Output Leakage
DISCNCT = GND
TRMPWR = 0V to 5.25V
REG = 0V
V
LINE
= 0 to 4V 10 400 nA
V
LINE
= 5.25V 100 µA
TRMPWR = 0V to 5.25V, REG = Open
V
LINE
= 0V to 5.25V
10 400 nA
Output Capacitance
DISCNCT = GND (Note 2) 6 7 pF
Regulator Section
Regulator Output Voltage 2.8 2.9 3 V
Regulator Output Voltage All Termination Lines = 4V 2.8 2.9 3 V
Line Regulation TRMPWR = 4V to 6V 10 20 mV
Drop Out Voltage All Termination Lines = 0.5V 1.0 1.2 V
Short Circuit Current V
REG
= 0V -450 -650 -950 mA
Sinking Current Capability V
REG
= 3.5V 100 200 500 mA
Thermal Shutdown 170 °C
Thermal Shutdown Hysteresis 10 °C
Disconnect Section
Disconnect Threshold 1.1 1.4 1.7 V
ELECTRICAL CHARACTERISTICS
Unless otherwise st at ed, th ese sp ecif icat io ns app ly for TA = 0°C to 70°C. TRM PWR =
4.75V, DISCNCT = 2 .4V . TA = TJ.
Note 1: Measuring each t ermin ation line while other 17 are low (0.5V).
Note 2: Guaranteed by des ig n. Not 100% tested in production.
Figure 1: Typical SCSI Bus Configuration
APPLICATION INFORMATION
UDG-94127
UNITRODE CORPORATI ON
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424- 24 10 • FAX (603) 424-3460
UC5609
3
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