ETC UC560T

UC560
27-Line SCSI Source/Sink Regulator
FEATURES
DESCRIPTION
• Complies with SCSI, SCSI-2, SCSI-3
SPI and Ultra SCSI (Fast-20)
The UC560 provides current for up to 27 lines of active termination for a
SCSI (Small Computers Systems Interface) parallel bus. The SCSI
standard requires active termination at both ends of the cable. The
UC560 is based on the UC5603 and UC5613 SCSI Active Terminators.
It uses the voltage regulator and internal logic circuits of those parts,
but has no termination circuits. The UC560 provides greater source current drive capability compared to the UC5603 and UC5613.
• 2.85V Regulated Output Voltage With
1.4% Tolerance
• Provides Current for up to 27 Lines of
Active Termination for SCSI Buses
• −750mA Sourcing Current for
Termination
• +300mA Sinking Current for Active
Negation Drivers
• 0.9V Dropout Voltage Regulator at
750mA and 2.75V Output
• 100µA Supply Current in Disconnect
Mode
The UC560 sink current maintains regulation with all active-negation
drivers negated. It provides a disconnect feature which disables the
regulator to greatly reduce standby power. Internal circuit trimming is
utilized for a 1.4% tolerance output voltage. Other features include thermal shutdown and current limit for short circuit conditions.
The UC560 is available in low thermal resistance versions of the industry standard 8-pin power SOIC, 5-pin TO-220 and 5-pin TO-263.
• Current Limit and Thermal Shutdown
Protection
• Low Thermal Resistance Surface Mount
Packages
BLOCK DIAGRAM
Pin Numbers refer to 8-pin DP package.
UDG-95136-1
SLUS213 - APRIL 1998
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UC560
CONNECTION DIAGRAMS
ABSOLUTE MAXIMUM RATINGS
TERMPWR Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
ENBL Voltage . . . . . . . . . . . . . . . . –0.3V to TERMPWR + 0.3V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4A
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5W
Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
SOIC-8 (Top View)
DP Package
Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.
RECOMMENDED OPERATING CONDITIONS
Note: Pins 2,3,6, and 7 are heat sinking pins. Pin 2 is the
connect point for electrical ground.
TERMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . . 4.0V to 6.0V
ENBL Voltage . . . . . . . . . . . . . . . . . . . . . . . . 0V to TERMPWR
5-Pin TO-220 (Top View)
T Package
5-Pin TO-263 (Top View)
TD Package
Note: TAB is ground.
Note: TAB is ground.
ELECTRICAL CHARACTERISTICS Unless otherwise specified, TA = 0°C to 70°C, TERMPWR = 4.75V, ENBL = 0V,
COUT = 4.7µF, CTERMPWR = 4.7µF, TA = TJ.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX UNITS
Supply Current Section
TERMPWR Supply Current
No Load
16
22
mA
IOUT = –700mA
Power Down Mode
ENBL = 2.0V
710
750
mA
100
140
µA
2.85
2.89
V
Regulator Section
Regulator Output Voltage
25°C, No Load
2.81
Load Regulation
IOUT = 300mA to –750mA (Note 2)
25
30
mV
Line Regulation
TERMPWR = 4.0V to 6.0V, No Load (Note 2)
10
20
mV
0.9
1.2
V
500
600
mA
1
2
mA
Dropout Voltage
IOUT = –750mA, VOUT = 2.75V
Short Circuit Current
VOUT = 0.0V
Sinking Current
VOUT = 3.5V
Thermal Shutdown
(Note 1)
170
°C
Thermal Shutdown Hysteresis
(Note 1)
10
°C
–0.85
ENBL = 2.0V, VOUT = 3.0V
–1.3
A
Shutdown Section
ENBL Threshold
1.1
1.4
Threshold Hysteresis
100
ENBL Output Current
–10
Note 1: Guaranteed by design. Not 100% tested in production.
Note 2: Tested at a constant junction temperature by low duty cycle pulse testing.
2
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1.7
V
mV
–15
µA
UC560
PIN DESCRIPTIONS
rent to prevent damage. When the part is in disabled
mode (ENBL ≥ 1.4V typical), the output goes to 0V with
no external supply source on OUT. The part will sink current, though, if there is an external supply voltage applied
to OUT when in disabled mode. For best perfomance, a
4.7µF low ESR capacitor is recommended.
ENBL: Enable Bar pin. The ENBL function is active low,
and the pin will source 10µA typically when at ground
and TERMPWR is between 4V and 6V. The part will go
into disable mode if ENBL is above 1.4V typical, and will
turn back on when ENBL drops below 1.3V typical. The
part also greatly reduces TERMPWR current when disabled (100µA typical).
TERMPWR: Supply voltage pin. The pin should be decoupled with at least a 2.2µF low ESR output capacitor.
For best perfomance, a 4.7µF low ESR capacitor is recommended. Lead lengths should be kept at a minimum.
GND: Ground pin.
OUT: 2.85V regulated output voltage pin. The part is internally current limited for both sinking and sourcing cur-
APPLICATIONS INFORMATION
UDG-96034
UDG-96033
Figure 1. Typical SCSI Bus Configuration Utilizing
UC560 Device
Figure 2. Typical Wide SCSI Bus Configuration
Utilizing UC560 Device
3
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UC560
TYPICAL CHARACTERISTICS
IOUT = -750mA
NO LOAD
IOUT = 300mA
LOAD REG (mV)
2.9
2.89
VOUT (V)
2.88
2.87
2.86
2.85
2.84
2.83
2.82
2.81
2.8
0
20
40
60
30
29
28
27
26
25
24
23
22
21
20
0
80
Figure 3. VOUT vs Temperature
40
60
80
Figure 5. Load Regulation vs. Temperature
(IOUT = 300mA to –750mA)
1.3
4
1.2
2
LINE REG (mV)
VIN - VOUT (V)
20
TEMPERATURE (°C)
TEMPERATURE (°C)
1.1
1
0.9
0.8
0
-2
-4
-6
-8
0.7
-10
-12
0.6
0
20
40
60
0
80
Figure 4. Dropout Voltage vs. Temperature
(IOUT = –750mA, VOUT = 2.75V)
40
60
Figure 6. Line Regulation vs Temperature
(TERMPWR = 4.0V to 6.0V)
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 • FAX (603) 424-3460
4
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20
TEMPERATURE (°C)
TEMPERATURE (°C)
80
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