TI UC5612

UC5612
9-Line Low Capacitance SCSI Active Terminator
FEATURES
DESCRIPTION
•
Complies with SCSI, SCSI-2
and SPI-2 Standards
•
5pF Channel Capacitance
during Disconnect
The UC5612 provides 9 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 segment.
•
Meets SCSI Hot Plugging
•
−400mA Sourcing Current for
Termination
•
+100mA Sinking Current for
Active Negation
•
1V Dropout Voltage Regulator
•
Logic High Command
Disconnects all Termination
Lines
•
100µA Supply Current in
Disconnect Mode
•
Trimmed Termination Current
to 5%
•
Trimmed Impedance to 5%
•
Low Thermal Resistance
Surface Mount Packages
The only functional differences between the UC5603 and UC5612 is the absence of the negative clamps on the output lines. Parametrically, the UC5612
has a 5% tolerance on impedance and current compared to a 3% tolerance on
the UC5603. Custom power packages are utilized to allow normal operation at
full power (2 Watts).
The UC5612 provides a disconnect feature which, when opened or driven high,
disconnects all terminating resistors, disables the regulator and greatly reduces
standby power consumption. The output channels remain high impedance even
without Termpwr applied. A low channel capacitance of 5pF allows interim
points of the bus to have little to no effect on the signal integrity.
Internal circuit trimming is utilized, first to trim the impedance to a 5% tolerance,
and then most importantly, to trim the output current to a 5% tolerance, as close
to the maximum SCSI specification as possible. This maximizes the 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 ZIP (zig-zag in line package) and 24 pin
TSSOP.
BLOCK DIAGRAM
UDG-94133
Circuit Design Patented
3/97
UC5612
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED OPERATING CONDITIONS
Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6A
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.
Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 3.8V to 5.25V
Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V
Disconnect Input Voltage . . . . . . . . . . . . . . . . . . 0V to Termpwr
CONNECTION DIAGRAMS
DIL-16 (Top View)
N or J Package
ZIP-16 (Top View)
Z Package
SOIC-16 (Top View)
DP Package
TSSOP-24 (Top View)
PWP Package
* DP package pin 5 serves as signal ground; pins 4, 12, 13
serve as heatsink/ground.
* PWP package pin 9 serves as signal ground; pins 5, 6, 7, 8,
17, 18, 19, and 20 serve as heatsink/ground.
Note: Drawings are not to scale.
2
UC5612
ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 0°C to 70°C.
TRMPWR = 4.75V, DISCNCT = 0V, TA = TJ.
PARAMETER
Supply Current Section
Termpwr Supply Current
TEST CONDITIONS
All termination lines = Open
All termination lines = 0.5V
Power Down Mode
DISCNCT = Open
Output Section (Termination Lines)
Terminator Impedance
∆ILINE = -5mA to -15mA
Output High Voltage
Max Output Current
VLINE = 0.5V
Max Output Current
Output Leakage
Output Capacitance
Regulator Section
Regulator Output Voltage
Line Regulation
Drop Out Voltage
Short Circuit Current
Sinking Current Capability
Thermal Shutdown
Thermal Shutdown Hysteresis
Disconnect Section
Disconnect Threshold
Input Current
TJ = 25°C
0°C < TJ < 70°C
VLINE = 0.5V, TRMPWR = 4V (Note 1) TJ = 25°C
0°C < TJ < 70°C
VLINE = 0.2V, TRMPWR = 4V to 5.25V 0°C < TJ < 70°C
DISCNCT = 4V
REG = 0V
VLINE = 0 to 4V
TRMPWR = 0V to 5.25V
VLINE = 5.25V
REG = Open VLINE = 0V to 5.25V
DISCNCT = Open (Note 2) (DP Package)
All Termination Lines = 4V
TRMPWR = 4V to 6V
All Termination Lines = 0.5V
REG = 0V
REG = 3.5V
MIN
104.5
2.65
-20.3
-19.8
-19.5
-19.0
-21.6
TYP
MAX
UNITS
17
200
100
23
225
150
mA
mA
µA
110
2.9
-21.5
-21.5
-21.5
-21.5
-24.0
10
115.5
3.1
-22.4
-22.4
-22.4
-22.4
-25.4
400
100
400
6
Ohms
V
mA
mA
mA
mA
mA
nA
µA
nA
pF
2.9
2.9
10
1.0
-400
100
170
10
3.1
3.1
20
1.2
-600
400
V
V
mV
V
mA
mA
°C
°C
1.4
-10
1.7
-20
V
µA
10
5
2.7
2.7
-200
75
1.1
DISCNCT = 0V
Note 1: Measuring each termination line while other 8 are low.
Note 2: Guaranteed by design. Not 100% tested in production.
APPLICATION INFORMATION
UDG-94134
Figure 1: Typical SCSI Bus Configurations Utilizing 2 UC5612 Devices
3
UC5612
APPLICATION INFORMATION (cont.)
UDG-94135
Figure 2: Typical Wide SCSI Bus Configurations Utilizing 3 UC5612 Devices.
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TEL. (603) 424-2410 • FAX (603) 424-3460
4
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