TI UC1-1

UC182-1,-2,-3,-ADJ
UC282-1,-2,-3,-ADJ
UC382-1,-2,-3,-ADJ
Fast LDO Linear Regulator
FEATURES
DESCRIPTION
• Fast Transient Response
The UC382 is a low dropout linear regulator providing a quick response to
fast load changes. Combined with its precision on-board reference, the
UC382 excels at driving GTL and BTL buses. Due to its fast response to
load transients, the total capacitance required to decouple the regulator’s
output can be significantly decreased when compared to standard LDO linear regulators.
• 10mA to 3A Load Current
• Short Circuit Protection
• Maximum Dropout of 450mV at 3A
Load Current
• Separate Bias and VIN Pins
• Available in Adjustable or Fixed
Output Voltages
• 5 Pin Package allows Kelvin Sensing
of Load Voltage
• Reverse Current Protection
Dropout voltage (VIN to VOUT) is only 450mV maximum at 100°C and
350mV typical at 3A load.
The on-board bandgap reference is stable with temperature and scaled for
a 1.200V input to the internal power amplifier. The UC382 is available in
fixed output voltages of 1.5V, 2.1V, or 2.5V. The output voltage of the adjustable version can be set with two external resistors. If the external resistors
are omitted, the output voltage defaults to 1.2V.
BLOCK DIAGRAM
UDG-96037-1
SLUS317 - JANUARY 1999
UC182-1,-2,-3,-ADJ
UC282-1,-2,-3,-ADJ
UC382-1,-2,-3,-ADJ
ABSOLUTE MAXIMUM RATINGS
ORDERING INFORMATION
VB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13V
VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7.5V
Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . +1.2V to 6.0V
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C
Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C
Temperature Range
Package
Output Voltage
1: –55°C to +125°C T: TO-220
1: 1.5V
2: –25°C to +100°C TD: TO-263 2: 2.1V
3: 0°C to +100°C
3: 2.5V
ADJ: 1.2V or Adjustable
Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages.
CONNECTION DIAGRAMS
5-Pin TO-220 (Top View)
T Package
5-Pin TO-263 (Top View)
TD Package
Note: Tab tied to Pin 3.
Note: Tab tied to Pin 3.
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these parameters apply for TA = –55°C to 125°C for the
UC182-X series, –25°C to +100°C for the UC282-X series and 0°C to +100°C for the UC382-X, VB = 5V; VIN = 3.3V, VOUT =
2.5V for the UC382-ADJ, TA = TJ.
PARAMETERS
TEST CONDITIONS
MIN
TYP
MAX UNITS
UC382-3
2.475
2.500
2.525
UC282-3 and UC182-3
2.450
2.500
2.525
V
0.5
4
mV
UC382-3 Fixed 2.5V, 3A Family
Output Voltage (IVOUT = 100mA)
Load Regulation
IVOUT = 10mA to 3A
V
VIN PSSR
80
100
dB
VB PSSR
50
60
dB
VIN Dropout Voltage = VIN–VOUT
VB Dropout = VB–VOUT
IVOUT = 3A, TJ = 25°C
350
425
mV
IVOUT = 3A, UC382-3
350
450
mV
IVOUT = 3A, UC282-3 and UC182-3
350
500
mV
IVOUT = 3A, UC382-3
1.8
2.10
V
IVOUT = 3A, UC282-3
1.8
2.20
V
IVOUT = 3A, UC182-3
1.8
2.35
V
Short Circuit Current Limit
VB Current
VIN Current
4.5
A
IVOUT = 10mA
3.3
6
9
mA
IVOUT = 3A
18
60
mA
IVOUT = 3A
2.94
2.97
A
UC382-2
2.079
2.100
2.121
V
UC282-2 and UC182-2
2.058
2.100
2.121
V
0.5
4
mV
80
100
UC382-2 Fixed 2.1V, 3A Family
Output Voltage (IVOUT = 100mA)
Load Regulation
IVOUT = 10mA to 3A
VIN PSSR
2
dB
UC182-1,-2,-3,-ADJ
UC282-1,-2,-3,-ADJ
UC382-1,-2,-3,-ADJ
ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these parameters apply for TA = –55°C to 125°C for the
UC182-X series, –25°C to +100°C for the UC282-X series and 0°C to +100°C for the UC382-X, VB = 5V; VIN = 3.3V, VOUT =
2.5V for the UC382-ADJ, TA = TJ.
PARAMETERS
TEST CONDITIONS
MIN
TYP
52
62
MAX UNITS
UC382-2 Fixed 2.1V, 3A Family (cont.)
VB PSSR
VIN Dropout Voltage = VIN–VOUT
VB Dropout = VB–VOUT
IVOUT = 3A, TJ = 25°C
350
425
mV
IVOUT = 3A, UC382-2
350
450
mV
IVOUT = 3A, UC282-2 and UC182-2
350
500
mV
IVOUT = 3A, UC382-2
1.8
2.10
V
IVOUT = 3A, UC282-2
1.8
2.20
V
1.8
2.35
V
4.5
A
IVOUT = 3A, UC182-2
Short Circuit Current Limit
VB Current
VIN Current
dB
3.3
IVOUT = 10mA
6
9
mA
IVOUT = 3A
18
60
mA
IVOUT = 3A
2.94
2.97
A
UC382-1
1.485 1.500
1.515
V
UC282-1 and UC182-1
1.470
1.500
1.515
V
0.5
4
mV
80
100
UC382-1 Fixed 1.5V, 3A Family
Output Voltage (IVOUT = 100mA)
Load Regulation
IVOUT = 10mA to 3A
VIN PSSR
VB PSSR
VIN Dropout Voltage = VIN–VOUT
VB Dropout = VB–VOUT
55
dB
350
425
mV
IVOUT = 3A, UC282-1
350
450
mV
IVOUT = 3A, UC282-2 and UC182-1
350
500
mV
IVOUT = 3A, UC382-1
1.8
2.10
V
IVOUT = 3A, UC282-1
1.8
2.20
V
1.8
2.35
V
IVOUT = 3A, UC182-1
3.3
IVOUT = 10mA
IVOUT = 3A
VIN Current
65
IVOUT = 3A, TJ = 25°C
Short Circuit Current Limit
VB Current
dB
4.5
A
6
9
mA
18
60
mA
IVOUT = 3A
2.94
2.97
A
UC382-ADJ
1.188
1.200
1.212
UC282-ADJ and UC182-ADJ
1.176
1.200
1.212
V
0.5
4
mV
UC382-ADJ Adjustable, 3A Family
ADJ Voltage (IVOUT = 100 mA)
V
Load Regulation
IVOUT = 10mA to 3A
VIN PSSR
VOUT Programmed for 2.5V
80
100
dB
VB PSSR
VOUT Programmed for 2.5V
50
60
dB
VIN Dropout Voltage = VIN–VOUT
VB Dropout = VB–VOUT
IVOUT = 3A, TJ = 25°C
350
425
mV
IVOUT = 3A, UC382-ADJ
350
450
mV
IVOUT = 3A, UC282-ADJ and UC182-ADJ
350
500
mV
IVOUT = 3A, UC382-ADJ
1.8
2.10
V
1.8
2.20
V
4.5
A
IVOUT = 3A, UC282-ADJ
Short Circuit Current Limit
VB Current
VIN Current
3.3
IVOUT = 10mA
6
9
mA
IVOUT = 3A
18
60
mA
IVOUT = 3A
2.94
3
2.97
A
UC182-1,-2,-3,-ADJ
UC282-1,-2,-3,-ADJ
UC382-1,-2,-3,-ADJ
PIN DESCRIPTIONS
impedance and fast response. (Dropout is derated for
junction temperatures below 0°C.)
ADJ: In the adjustable version, the user programs the
output voltage with two external resistors. The resistors
should be 0.1% for high accuracy. The output amplifier is
configured as a non-inverting operational amplifier. The
resistors should meet the criteria of R3 || R4 < 100Ω.
Connect ADJ to VOUT for an output voltage of 1.2V. Note
that the point at which the feedback network is
connected to the output is the Kelvin sense point.
VIN: Supplies the current to the collector of the output
power transistor only. The dropout (VIN-VOUT) is under
100mV for light loads; maximum dropout is 450mV at 3A
for TJ = 0°C to +110°C. (Dropout is derated for junction
temperatures over 110°C.) At full load, the majority of the
VB current is going to the load.
GND: For accurate results, the GND pin should be
referenced to the load ground.
VOUT: This pin should be connected to the load via a
low impedance path. Avoid connectors which add
significant inductance and resistance. Note that even
though a Kelvin sense is available through a 5 pin
package, care must be taken since voltage drops along
wire traces add to the dropout voltage.
VB: Supplies power to all circuits of the regulator except
the collector of the output power transistor. The 2V
headroom from VB to VOUT allows the use of a
Darlington output stage for inherently low output
400
VDROPOUT (mV)
VDROPOUT (V)
1.9
1.8
1.7
1
2
200
100
100mA
1.6
0
300
3
1A
2A
3A
IL
IL (A)
Figure 2. Typical Dropout (VIN - VOUT), TJ = 27°C
Figure 1. Typical Dropout (VB - VOUT), TJ = 27°C
APPLICATION INFORMATION
will vary according to speed and magnitude of the load
transients and the tolerance allowed for transients on
VOUT. When specifying the decoupling capacitors, the
series resistance of the capacitor bank is an important
factor in its ability to filter load transients.
The UC382 is easy to use. The adjustable version requires two 0.1% resistors to set the output voltage. The
fixed versions of the UC382 require no external resistors.
All versions of the UC382 require decoupling capacitors
on the input and output. In a typical application, VB and
VIN are driven from switching power supplies which may
have large filter capacitors at their outputs. If the UC382
is further than 12 inches from the power supply, it is recommended to add local decoupling as close as possible
to the linear regulator.
The UC382 allows for Kelvin sensing the voltage at the
load. This improves regulation performance and eliminates the voltage drops due to wire trace resistance. This
voltage drop must be added to the headroom (VIN to
VOUT and VB to VOUT). The dropout of 450mV is measured at the pins and does not include additional drops
due to trace resistance. The minimum load current is
10mA.
Decouple the output of the UC382 with at least 100µF of
high quality tantalum or Sanyo OSCON capacitors close
to the VOUT pin for maximum stability. Many applications
involving ultra fast GTL or BTL applications require additional capacitance close to the load. The exact amount
Two or more UC382’s may be used in parallel. While stable, this arrangement does degrade the transient response.
4
UC182-1,-2,-3,-ADJ
UC282-1,-2,-3,-ADJ
UC382-1,-2,-3,-ADJ
APPLICATION INFORMATION (cont.)
Figure 3. Open Loop Gain (100µF Output
Capacitance, 1A Load).
Figure 4. Open Loop Phase (100µF Output
Capacitance, 1A Load).
60
50
dB
40
30
20
10
0
100
1k
10k
100k
1M
10M
FREQUENCY (Hz)
Figure 5. PSRR (VB) 2.5V Out.
UDG-96038
Figure 6. Transient test circuit.
5
UC182-1,-2,-3,-ADJ
UC282-1,-2,-3,-ADJ
UC382-1,-2,-3,-ADJ
APPLICATION INFORMATION (cont.)
∆VO
10mV/DIV
IL
1A/DIV
2µs/DIV
Figure 7. 10mA to 3A/µs load transient response.
UDG-96039
UDG-96040
Figure 8. Typical UC382-ADJ application
Figure 9. Typical UC382-1, -2, or -3 application
UNITRODE CORPORATION
7 CONTINENTAL BLVD. • MERRIMACK, NH 03054
TEL. (603) 424-2410 FAX (603) 424-3460
6