LT3080 Datasheet

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Datasheet

LT3080
1
3080fc
Adjustable1.1A Single
Resistor Low Dropout
Regulator
The LT
®
3080 is a 1.1A low dropout linear regulator that can
be paralleled to increase output current or spread heat in
surface mounted boards. Architected as a precision cur-
rent source and voltage follower allows this new regulator
to be used in many applications requiring high current,
adjustability to zero, and no heat sink. Also the device
brings out the collector of the pass transistor to allow low
dropout operation —down to 350 millivolts— when used
with multiple supplies.
A key feature of the LT3080 is the capability to supply a
wide output voltage range. By using a reference current
through a single resistor, the output voltage is programmed
to any level between zero and 36V. The LT3080 is stable
with 2.2µF of capacitance on the output, and the IC uses
small ceramic capacitors that do not require additional
ESR as is common with other regulators.
Internal protection circuitry includes current limiting and
thermal limiting. The LT3080 regulator is offered in the
8-lead MSOP (with an exposed pad for better thermal
characteristics), a 3mm × 3mm DFN, 5-lead DD-Pak,
TO-220 and a simple-to-use 3-lead SOT-223 version.
n High Current All Surface Mount Supply
n High Efficiency Linear Regulator
n Post Regulator for Switching Supplies
n Low Parts Count Variable Voltage Supply
n Low Output Voltage Power Supplies
n Outputs May be Paralleled for Higher Current and
Heat Spreading
n Output Current: 1.1A
n Single Resistor Programs Output Voltage
n 1% Initial Accuracy of SET Pin Current
n Output Adjustable to 0V
n Low Output Noise: 40µVRMS (10Hz to 100kHz)
n Wide Input Voltage Range: 1.2V to 36V
n Low Dropout Voltage: 350mV (Except SOT-223
Package)
n <1mV Load Regulation
n <0.001%/V Line Regulation
n Minimum Load Current: 0.5mA
n Stable with 2.2µF Minimum Ceramic Output Capacitor
n Current Limit with Foldback and Overtemperature
Protected
n Available in 8-Lead MSOP, 3mm × 3mm DFN,
5-Lead DD-Pak, TO-220 and 3-Lead SOT-223
Variable Output Voltage 1.1A Supply
+
LT3080
IN
VIN
1.2V TO 36V
VCONTROL
OUT
3080 TA01a
SET
1µF
2.2µF
RSET
VOUT = RSET • 10µA
VOUT
Set Pin Current Distribution
SET PIN CURRENT DISTRIBUTION (µA)
10.20
3080 G02
9.90 10.00 10.10
9.80
N = 13792
Typical applicaTion
DescripTion
FeaTures
applicaTions
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and VLDO
and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
LT3080
2
3080fc
absoluTe MaxiMuM raTings
VCONTROL Pin Voltage ..................................... 40V, –0.3V
IN Pin Voltage ................................................ 40V, –0.3V
SET Pin Current (Note 7) .....................................±10mA
SET Pin Voltage (Relative to OUT) .........................±0.3V
Output Short-Circuit Duration .......................... Indefinite
(Note 1)(All Voltages Relative to VOUT)
TOP VIEW
9
OUT
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
5
6
7
8
4
3
2
1OUT
OUT
OUT
SET
IN
IN
NC
VCONTROL
TJMAX = 125°C, θJA = 64°C/W, θJC = 3°C/W
EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB
1
2
3
4
OUT
OUT
OUT
SET
8
7
6
5
IN
IN
NC
VCONTROL
TOP VIEW
MS8E PACKAGE
8-LEAD PLASTIC MSOP
9
OUT
TJMAX = 125°C, θJA = 60°C/W, θJC = 10°C/W
EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB
Q PACKAGE
5-LEAD PLASTIC DD-PAK
TAB IS
OUT
FRONT VIEW
IN
VCONTROL
OUT
SET
NC
5
4
3
2
1
TJMAX = 125°C, θJA = 30°C/W, θJC = 3°C/W
T PACKAGE
5-LEAD PLASTIC TO-220
IN
VCONTROL
OUT
SET
NC
FRONT VIEW
5
4
3
2
1
TAB IS
OUT
TJMAX = 125°C, θJA = 40°C/W, θJC = 3°C/W
3
2
1
FRONT VIEW
TAB IS
OUT
IN*
OUT
SET
ST PACKAGE
3-LEAD PLASTIC SOT-223
*IN IS VCONTROL AND IN TIED TOGETHER
TJMAX = 125°C, θJA = 55°C/W, θJC = 15°C/W
Operating Junction Temperature Range (Notes 2, 10)
E-, I-Grades ............................................ –40°C to 125°C
Storage Temperature Range: .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MS8E, Q, T and ST Packages Only .................... 300°C
pin conFiguraTion
LT3080
3
3080fc
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3080EDD#PBF LT3080EDD#TRPBF LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C
LT3080IDD#PBF LT3080IDD#TRPBF LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C
LT3080EMS8E#PBF LT3080EMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C
LT3080IMS8E#PBF LT3080IMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C
LT3080EQ#PBF LT3080EQ#TRPBF LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C
LT3080IQ#PBF LT3080IQ#TRPBF LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C
LT3080ET#PBF LT3080ET#TRPBF LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C
LT3080IT#PBF LT3080IT#TRPBF LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C
LT3080EST#PBF LT3080EST#TRPBF 3080 3-Lead Plastic SOT-223 –40°C to 125°C
LT3080IST#PBF LT3080IST#TRPBF 3080 3-Lead Plastic SOT-223 –40°C to 125°C
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LT3080EDD LT3080EDD#TR LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C
LT3080IDD LT3080IDD#TR LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C
LT3080EMS8E LT3080EMS8E#TR LTCBM 8-Lead Plastic MSOP –40°C to 125°C
LT3080IMS8E LT3080IMS8E#TR LTCBM 8-Lead Plastic MSOP –40°C to 125°C
LT3080EQ LT3080EQ#TR LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C
LT3080IQ LT3080IQ#TR LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C
LT3080ET LT3080ET#TR LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C
LT3080IT LT3080IT#TR LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C
LT3080EST LT3080EST#TR 3080 3-Lead Plastic SOT-223 –40°C to 125°C
LT3080IST LT3080IST#TR 3080 3-Lead Plastic SOT-223 –40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
LT3080
4
3080fc
PARAMETER CONDITIONS MIN TYP MAX UNITS
SET Pin Current ISET VIN = 1V, VCONTROL = 2.0V, ILOAD = 1mA, TJ = 25°C
VIN ≥ 1V, VCONTROL ≥ 2.0V, 1mA ≤ ILOAD ≤ 1.1A (Note 9)
l
9.90
9.80
10
10
10.10
10.20
µA
µA
Output Offset Voltage (VOUT – VSET)
VIN = 1V, VCONTROL = 2V, IOUT = 1mA
VOS DFN and MSOP Package
l
–2
–3.5
2
3.5
mV
mV
SOT-223, DD-Pak and T0-220 Package
l
–5
–6
5
6
mV
mV
Load Regulation ΔISET
ΔVOS
ΔILOAD = 1mA to 1.1A
ΔILOAD = 1mA to 1.1A (Note 8)
l
–0.1
0.6
1.3
nA
mV
Line Regulation (Note 9)
DFN and MSOP Package ΔISET
ΔVOS
VIN = 1V to 25V, VCONTROL = 2V to 25V, ILOAD = 1mA
VIN = 1V to 25V, VCONTROL = 2V to 25V, ILOAD = 1mA
l 0.1
0.003
0.5 nA/V
mV/V
Line Regulation (Note 9)
SOT-223, DD-Pak and T0-220 Package
ΔISET
ΔVOS
VIN = 1V to 26V, VCONTROL = 2V to 26V, ILOAD = 1mA
VIN = 1V to 26V, VCONTROL = 2V to 26V, ILOAD = 1mA
l0.1
0.003
0.5 nA/V
mV/V
Minimum Load Current (Notes 3, 9) VIN = VCONTROL = 10V
VIN = VCONTROL = 25V (DFN and MSOP Package)
VIN = VCONTROL = 26V (SOT-223, DD-Pak and T0-220 Package)
l
l
l
300 500
1
1
µA
mA
mA
VCONTROL Dropout Voltage (Note 4) ILOAD = 100mA
ILOAD = 1.1A
l
1.2
1.35
1.6
V
V
VIN Dropout Voltage (Note 4) ILOAD = 100mA
ILOAD = 1.1A
l
l
100
350
200
500
mV
mV
VCONTROL Pin Current ILOAD = 100mA
ILOAD = 1.1A
l
l
4
17
6
30
mA
mA
Current Limit VIN = 5V, VCONTROL = 5V, VSET = 0V, VOUT = –0.1V l1.1 1.4 A
Error Amplifier RMS Output Noise (Note 6) ILOAD = 1.1A, 10Hz ≤ f ≤ 100kHz, COUT = 10µF, CSET = 0.1µF 40 µVRMS
Reference Current RMS Output Noise (Note 6) 10Hz ≤ f ≤ 100kHz 1 nARMS
Ripple Rejection f = 120Hz, VRIPPLE = 0.5VP-P , I
LOAD = 0.2A, CSET = 0.1µF, COUT = 2.2µF
f = 10kHz
f = 1MHz
75
55
20
dB
dB
dB
Thermal Regulation, ISET 10ms Pulse 0.003 %/W
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Unless otherwise specified, all voltages are with respect to VOUT.
The LT3080 is tested and specified under pulse load conditions such that
TJ TA. The LT3080E is tested at TA = 25°C. Performance of the LT3080E
over the full –40°C and 125°C operating temperature range is assured by
design, characterization, and correlation with statistical process controls.
The LT3080I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3: Minimum load current is equivalent to the quiescent current of
the part. Since all quiescent and drive current is delivered to the output
of the part, the minimum load current is the minimum current required to
maintain regulation.
Note 4: For the LT3080, dropout is caused by either minimum control
voltage (VCONTROL) or minimum input voltage (VIN). Both parameters are
specified with respect to the output voltage. The specifications represent the
minimum input-to-output differential voltage required to maintain regulation.
Note 5: The VCONTROL pin current is the drive current required for the
output transistor. This current will track output current with roughly a 1:60
ratio. The minimum value is equal to the quiescent current of the device.
Note 6: Output noise is lowered by adding a small capacitor across the
voltage setting resistor. Adding this capacitor bypasses the voltage setting
resistor shot noise and reference current noise; output noise is then equal
to error amplifier noise (see Applications Information section).
Note 7: SET pin is clamped to the output with diodes. These diodes only
carry current under transient overloads.
Note 8: Load regulation is Kelvin sensed at the package.
Note 9: Current limit may decrease to zero at input-to-output differential
voltages (VIN–VOUT) greater than 25V (DFN and MSOP package) or 26V
(SOT-223, DD-Pak and T0-220 Package). Operation at voltages for both IN
and VCONTROL is allowed up to a maximum of 36V as long as the difference
between input and output voltage is below the specified differential
(VIN–VOUT) voltage. Line and load regulation specifications are not
applicable when the device is in current limit.
Note 10: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature when
overtemperature protection is active. Continuous operation above the specified
maximum operating junction temperature may impair device reliability.
Note 11: The SOT-223 package connects the IN and VCONTROL pins
together internally. Therefore, test conditions for this pin follow the
VCONTROL conditions listed in the Electrical Characteristics Table.
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. (Note 11)
LT3080
5
3080fc
Set Pin Current Set Pin Current Distribution Offset Voltage (VOUT – VSET)
Offset Voltage Offset Voltage
Load Regulation Minimum Load Current
Dropout Voltage
(Minimum IN Voltage)
TEMPERATURE (°C)
–50
SET PIN CURRENT (µA)
10.00
10.10
150
3080 G01
9.90
9.80 050 100
–25 25 75 125
10.20
9.95
10.05
9.85
10.15
SET PIN CURRENT DISTRIBUTION (µA)
10.20
3080 G02
9.90 10.00 10.10
9.80
N = 13792
TEMPERATURE (°C)
–50
OFFSET VOLTAGE (mV)
0
1.0
150
3080 G03
–1.0
–2.0 050 100
–25 25 75 125
2.0
–0.5
0.5
–1.5
1.5
IL = 1mA
VOS DISTRIBUTION (mV)
2
3080 G04
–1 01
–2
N = 13250
INPUT-TO-OUTPUT VOLTAGE (V)
0
OFFSET VOLTAGE (mV)
–0.25
0
0.25
18 30
3080 G05
–0.50
–0.75
–1.00 6 12 24
0.50
0.75
1.00
36*
ILOAD = 1mA
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
LOAD CURRENT (A)
0
OFFSET VOLTAGE (mV)
–1.00
–0.75
–0.50
0.6 1.0
3080 G06
–1.25
–1.50
–1.75 0.2 0.4 0.8
–0.25
0
0.25
1.2
TJ = 25°C
TJ = 125°C
TEMPERATURE (°C)
–50
CHANGE IN OFFSET VOLTAGE WITH LOAD (mV)
CHANGE IN REFERENCE CURRENT WITH LOAD (nA)
–0.4
–0.2
150
3080 G07
–0.6
–0.8 050 100
–25 25 75 125
0
–0.5
–0.3
–0.7
–0.1
–20
0
–40
–60
20
–30
–10
–50
10
∆ILOAD = 1mA TO 1.1A
VIN – VOUT = 2V
CHANGE IN REFERENCE CURRENT
CHANGE IN OFFSET VOLTAGE
(VOUT – VSET)
TEMPERATURE (°C)
–50
MINIMUM LOAD CURRENT (mA)
0.4
0.6
150
3080 G08
0.2
0050 100
–25 25 75 125
0.8
0.3
0.5
0.1
0.7
VIN, CONTROL – VOUT = 36V*
VIN, CONTROL – VOUT = 1.5V
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
OUTPUT CURRENT (A)
0
MINIMUM IN VOLTAGE (VIN – VOUT) (mV)
150
200
250
0.6 1.0
3080 G09
100
50
00.2 0.4 0.8
300
350
400
1.2
TJ = 25°C
TJ = 125°C
Offset Voltage Distribution
Typical perForMance characTerisTics
LT3080
6
3080fc
Typical perForMance characTerisTics
TIME (µs)
0
OUTPUT VOLTAGE
DEVIATION (mV)LOAD CURRENT (mA)
–25
25
75
40
3080 G15
400
200
–50
0
50
300
100
0105 2015 30 35 45
25 50
VOUT = 1.5V
CSET = 0.1µF
VIN = VCONTROL = 3V
COUT = 10µF CERAMIC
COUT = 2.2µF CERAMIC
Dropout Voltage
(Minimum IN Voltage)
Dropout Voltage (Minimum
VCONTROL Pin Voltage)
Dropout Voltage (Minimum
VCONTROL Pin Voltage)
Current Limit Load Transient Response
TEMPERATURE (°C)
–50
MINIMUM IN VOLTAGE (VIN – VOUT) (mV)
200
300
150
3080 G10
100
0050 100
–25 25 75 125
400
150
250
50
350 ILOAD = 1.1A
ILOAD = 500mA
ILOAD = 100mA
OUTPUT CURRENT (A)
0
MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V)
0.6
0.8
1.0
0.6 1.0
3080 G11
0.4
0.2
00.2 0.4 0.8
1.2
1.4
1.6
1.2
TJ = 125°C
TJ = –50°C
TJ = 25°C
TEMPERATURE (°C)
–50
MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V)
0.8
1.2
150
3080 G12
0.4
0050 100
–25 25 75 125
1.6
0.6
1.0
0.2
1.4 ILOAD = 1.1A
ILOAD = 1mA
Current Limit
TEMPERATURE (°C)
–50
CURRENT LIMIT (A)
0.8
1.2
150
3080 G13
0.4
0050 100
–25 25 75 125
1.6
0.6
1.0
0.2
1.4
VIN = 7V
VOUT = 0V
INPUT-TO-OUTPUT DIFFERENTIAL (V)
0
CURRENT LIMIT (A)
0.6
0.8
1.0
18 30
3080 G14
0.4
0.2
06 12 24
1.2
1.4
1.6
36*
SOT-223, DD-PAK
AND TO-220
MSOP
AND
DFN
TJ = 25°C
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
TIME (µs)
0
OUTPUT VOLTAGE
DEVIATION (mV)LOAD CURRENT (A)
–50
50
150
40
3080 G16
1.2
0.6
–100
0
100
0.9
0.3
0105 2015 30 35 45
25 50
VIN = VCONTROL = 3V
VOUT = 1.5V
COUT = 10µF CERAMIC
CSET = 0.1µF
Load Transient Response Line Transient Response
TIME (µs)
0
IN/CONTROL VOLTAGE (V)
OUTPUT VOLTAGE
DEVIATION (mV)
–25
25
75
80
3080 G17
6
4
–50
0
50
5
3
22010 4030 60 70 90
50 100
VOUT = 1.5V
ILOAD = 10mA
COUT = 2.2µF
CERAMIC
CSET = 0.1µF
CERAMIC
Turn-On Response
TIME (µs)
0
OUTPUT VOLTAGE (V) INPUT VOLTAGE (V)
1
3
5
8
3080 G18
2.0
1.0
0
2
4
1.5
0.5
021 43 6 7 9
510
RSET = 100k
CSET = 0
RLOAD = 1Ω
COUT = 2.2µF CERAMIC
LT3080
7
3080fc
Typical perForMance characTerisTics
VCONTROL Pin Current
Residual Output Voltage with
Less Than Minimum Load
Ripple Rejection, Single Supply
Ripple Rejection, Dual Supply,
IN Pin
Ripple Rejection, Dual Supply,
VCONTROL Pin
VCONTROL Pin Current
Ripple Rejection (120Hz) Noise Spectral Density
INPUT-TO-OUTPUT DIFFERENTIAL (V)
0
0
CONTROL PIN CURRENT (mA)
5
10
15
20
25
612 18 24
3080 G19
30 36*
ILOAD = 1.1A
ILOAD = 1mA
DEVICE IN
CURRENT LIMIT
*SEE NOTE 9 IN ELECTRICAL
CHARACTERISTICS TABLE
LOAD CURRENT (A)
0
0
CONTROL PIN CURRENT (mA)
5
10
15
20
30
0.2 0.4 0.6 0.8
3080 G20
1.0 1.2
25
VCONTROL – VOUT = 2V
VIN – VOUT = 1V
TJ = –50°C
TJ = 125°C
TJ = 25°C
RTEST (Ω)
0
OUTPUT VOLTAGE (V)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
3080 G21
2k1k
VIN = 20V
VIN = 5V
SET PIN = 0V
VIN VOUT
RTEST
VIN = 10V
FREQUENCY (Hz)
0
RIPPLE REJECTION (dB)
40
100
10k 100k10010 1k 1M
3080 G22
20
60
80
30
90
10
50
70
VIN = VCONTROL = VOUT (NOMINAL) + 2V
RIPPLE = 50mVP-P
COUT = 2.2µF CERAMIC
ILOAD = 100mA
ILOAD = 1.1A
FREQUENCY (Hz)
0
40
10k 100k10010 1k 1M
3080 G23
20
60
80
30
90
10
50
70
VIN = VOUT (NOMINAL) + 1V
VCONTROL = VOUT (NOMINAL) +2V
COUT = 2.2µF CERAMIC
RIPPLE = 50mVP-P
ILOAD = 100mA
ILOAD = 1.1A
FREQUENCY (Hz)
0
RIPPLE REJECTION (dB)
40
100
10k 100k10010 1k 1M
3080 G24
20
60
80
30
90
10
50
70
VIN = VOUT (NOMINAL) + 1V
VCONTROL = VOUT (NOMINAL) +2V
RIPPLE = 50mVP-P
COUT = 2.2µF CERAMIC
ILOAD = 1.1A
TEMPERATURE (°C)
–50
70
RIPPLE REJECTION (dB)
71
73
74
75
80
77
050 75
3080 G25
72
78
79
76
–25 25 100 125 150
SINGLE SUPPLY OPERATION
VIN = VOUT(NOMINAL) + 2V
RIPPLE = 500mVP-P, f = 120Hz
ILOAD = 1.1A
CSET = 0.1µF, COUT = 2.2µF
FREQUENCY (Hz)
1
ERROR AMPLIFIER NOISE
SPECTRAL DENSITY (nV/√Hz)
REFERENCE CURRENT NOISE
SPECTRAL DENSITY (pA/ √Hz)
10k
10k 100k10010 1k
3080 G26
100
10
1k
0.1
1k
10
1.0
100
LT3080
8
3080fc
Typical perForMance characTerisTics
Output Voltage Noise Error Amplifier Gain and Phase
VCONTROL (Pin 5/Pin 5/Pin 4/Pin 4/NA): This pin is the
supply pin for the control circuitry of the device. The cur-
rent flow into this pin is about 1.7% of the output current.
For the device to regulate, this voltage must be more than
1.2V to 1.35V greater than the output voltage (see dropout
specifications).
IN (Pins 7, 8/Pins 7, 8/Pin 5/Pin 5/Pin 3): This is the
collector to the power device of the LT3080. The output
load current is supplied through this pin. For the device
to regulate, the voltage at this pin must be more than
0.1V to 0.5V greater than the output voltage (see dropout
specifications).
NC (Pin 6/Pin 6/Pin 1/Pin 1/NA): No Connection. No con-
nect pins have no connection to internal circuitry and may
be tied to VIN, VCONTROL, VOUT , GND or floated.
OUT (Pins 1-3/Pins 1-3/Pin 3/Pin 3/Pin 2): This is the
power output of the device. There must be a minimum
load current of 1mA or the output may not regulate.
SET (Pin 4/Pin 4/Pin 2/Pin 2/Pin 1): This pin is the input
to the error amplifier and the regulation set point for
the device. A fixed current of 10µA flows out of this pin
through a single external resistor, which programs the
output voltage of the device. Output voltage range is zero
to the absolute maximum rated output voltage. Transient
performance can be improved by adding a small capacitor
from the SET pin to ground.
Exposed Pad (Pin 9/Pin 9/NA/NA/NA): OUT on MS8E and
DFN packages.
TAB: OUT on DD-Pak, TO-220 and SOT-223 packages.
pin FuncTions
(DD/MS8E/Q/T/ST)
VOUT
100µV/DIV
TIME 1ms/DIV 3080 G27
VOUT = 1V
RSET = 100k
CSET = O.1µF
COUT = 10µF
ILOAD = 1.1A
FREQUENCY (Hz)
–30
GAIN (dB)
PHASE (DEGREES)
–10
20
10k 100k10010 1k 1M
3080 G28
–20
0
10
–15
15
–25
–5
5
–200
0
300
–100
100
200
–50
250
–150
50
150
IL = 1.1A
IL = 100mA
IL = 100mA
IL = 1.1A
LT3080
9
3080fc
The LT3080 regulator is easy to use and has all the pro-
tection features expected in high performance regulators.
Included are short-circuit protection and safe operating
area protection, as well as thermal shutdown.
The LT3080 is especially well suited to applications needing
multiple rails. The new architecture adjusts down to zero
with a single resistor handling modern low voltage digital
IC’s as well as allowing easy parallel operation and thermal
management without heat sinks. Adjusting to “zero” output
allows shutting off the powered circuitry and when the
input is pre-regulated—such as a 5V or 3.3V input supply
—external resistors can help spread the heat.
A precision “0” TC 10µA internal current source is con-
nected to the noninverting input of a power operational
amplifier. The power operational amplifier provides a low
impedance buffered output to the voltage on the noninvert-
ing input. A single resistor from the noninverting input to
ground sets the output voltage and if this resistor is set
to zero, zero output results. As can be seen, any output
voltage can be obtained from zero up to the maximum
defined by the input power supply.
What is not so obvious from this architecture are the ben-
efits of using a true internal current source as the reference
as opposed to a bootstrapped reference in older regulators.
A true current source allows the regulator to have gain
and frequency response independent of the impedance on
the positive input. Older adjustable regulators, such as the
LT1086 have a change in loop gain with output voltage
as well as bandwidth changes when the adjustment pin
is bypassed to ground. For the LT3080, the loop gain is
unchanged by changing the output voltage or bypassing.
Output regulation is not fixed at a percentage of the output
voltage but is a fixed fraction of millivolts. Use of a true
current source allows all the gain in the buffer amplifier
to provide regulation and none of that gain is needed to
amplify up the reference to a higher output voltage.
The LT3080 has the collector of the output transistor
connected to a separate pin from the control input. Since
the dropout on the collector (IN pin) is only 350mV, two
supplies can be used to power the LT3080 to reduce dis-
sipation: a higher voltage supply for the control circuitry
and a lower voltage supply for the collector. This increases
efficiency and reduces dissipation. To further spread the
heat, a resistor can be inserted in series with the collector
to move some of the heat out of the IC and spread it on
the PC board.
The LT3080 can be operated in two modes. Three-terminal
mode has the control pin connected to the power input pin
which gives a limitation of 1.35V dropout. Alternatively,
the “control” pin can be tied to a higher voltage and the
power IN pin to a lower voltage giving 350mV dropout
on the IN pin and minimizing the power dissipation. This
allows for a 1.1A supply regulating from 2.5VIN to 1.8VOUT
or 1.8VIN to 1.2VOUT with low dissipation.
+
VCONTROL
IN
10µA
3080 BD
OUTSET
block DiagraM
applicaTions inForMaTion
LT3080
10
3080fc
Figure 1. Basic Adjustable Regulator
+
LT3080
IN
VCONTROL
VCONTROL
OUT
3080 F01
SET
COUT
RSET
VOUT
CSET
+
VIN
+
Output Voltage
The LT3080 generates a 10µA reference current that flows
out of the SET pin. Connecting a resistor from SET to
ground generates a voltage that becomes the reference
point for the error amplifier (see Figure 1). The reference
voltage is a straight
multiplication of the SET pin current
and the value of the resistor. Any voltage can be generated
and there is no minimum output voltage for the regulator.
A minimum load current of 1mA is required to maintain
regulation regardless of output voltage. For true zero
voltage output operation, this 1mA load current must be
returned to a negative supply voltage.
With the low level current used to generate the reference
voltage, leakage paths to or from the SET pin can create
errors in the reference and output voltages. High quality
insulation should be used (e.g., Teflon, Kel-F); cleaning
of all insulating surfaces to remove fluxes and other resi-
dues will probably be required. Surface coating may be
necessary to provide a moisture barrier in high humidity
environments.
Board leakage can be minimized by encircling the SET
pin and circuitry with a guard ring operated at a potential
close to itself; the guard ring should be tied to the OUT
pin. Guarding both sides of the circuit board is required.
Bulk leakage reduction depends on the guard ring width.
Ten nanoamperes of leakage into or out of the SET pin and
associated circuitry creates a 0.1% error in the reference
voltage. Leakages of this magnitude, coupled with other
sources of leakage, can cause significant offset voltage
and reference drift, especially over the possible operating
temperature range.
If guardring techniques are used, this bootstraps any
stray capacitance at the SET pin. Since the SET pin is
a high impedance node, unwanted signals may couple
into the SET pin and cause erratic behavior. This will
be most noticeable when operating with minimum
output capacitors at full load current. The easiest way
to remedy this is to bypass the SET pin with a small
amount of capacitance from SET to ground, 10pF to
20pF is sufficient.
Stability and Output Capacitance
The LT3080 requires an output capacitor for stability. It
is designed to be stable with most low ESR capacitors
(typically ceramic, tantalum or low ESR electrolytic).
A minimum output capacitor of 2.2µF with an ESR of 0.5Ω
or less is recommended to prevent oscillations.
Larger
values of output capacitance decrease peak
deviations
and provide improved transient response for larger load
current changes. Bypass capacitors, used to decouple
individual components powered by the LT3080, increase
the effective output capacitor value.
For improvement in transient performance, place a capaci-
tor across the voltage setting resistor. Capacitors up to
1µF can be used. This bypass capacitor reduces system
noise as well, but start-up time is proportional to the time
constant of the voltage setting resistor (R
SET
in Figure 1)
and SET pin bypass capacitor.
Extra consideration must be given to the use of ceramic
capacitors. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior across
temperature and applied voltage. The most common
dielectrics used are specified with EIA temperature char-
acteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but they tend to have strong volt-
age and temperature coefficients as shown in Figures 2
and 3. When used with a 5V regulator, a 16V 10µF Y5V
capacitor can exhibit an effective value as low as 1µF to
2µF for the DC bias voltage applied and over the operating
temperature range. The X5R and X7R dielectrics result in
more stable characteristics and are more suitable for use
as the output capacitor. The X7R type has better stability
across temperature, while the X5R is less expensive and is
applicaTions inForMaTion
LT3080
11
3080fc
available in higher values. Care still must be exercised when
using X5R and X7R capacitors; the X5R and X7R codes
only specify operating temperature range and maximum
capacitance change over temperature. Capacitance change
due to DC bias with X5R and X7R capacitors is better than
Y5V and Z5U capacitors, but can still be significant enough
to drop capacitor values below appropriate levels. Capaci-
tor DC bias characteristics tend to improve as component
case size increases, but expected capacitance at operating
voltage should be verified.
Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates
voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric microphone works. For a
ceramic capacitor the stress can be induced by vibrations
in the system or thermal transients.
Paralleling Devices
LT3080’s may be paralleled to obtain higher output current.
The SET pins are tied together and the IN pins are tied
together. This is the same whether it’s in three terminal
mode or has separate input supplies. The outputs are
connected in common using a small piece of PC trace
as a ballast resistor to equalize the currents. PC trace
resistance in milliohms/inch is shown in Table 1. Only a
tiny area is needed for ballasting.
Table 1. PC Board Trace Resistance
WEIGHT (oz) 10 mil WIDTH 20 mil WIDTH
1 54.3 27.1
2 27.1 13.6
Trace resistance is measured in mOhms/in
The worse case offset between the set pin and the output
of only ± 2 millivolts allows very small ballast resistors
to be used. As shown in Figure 4, the two devices have
a small 10 milliohm ballast resistor, which at full output
current gives better than 80 percent equalized sharing
of the current. The external resistance of 10 milliohms
+
LT3080
VIN
VCONTROL
OUT
SET
10mΩ
+
LT3080
VIN
VIN
4.8V TO 28V
VOUT
3.3V
2A
VCONTROL
OUT
10µF
F
SET
165k
3080 F04
10mΩ
Figure 4. Parallel Devices
applicaTions inForMaTion
DC BIAS VOLTAGE (V)
CHANGE IN VALUE (%)
3080 F02
20
0
–20
–40
–60
–80
–100 04810
2 6 12 14
X5R
Y5V
16
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
Figure 2. Ceramic Capacitor DC Bias Characteristics
TEMPERATURE (°C)
–50
40
20
0
–20
–40
–60
–80
–100 25 75
3080 F03
–25 0 50 100 125
Y5V
CHANGE IN VALUE (%)
X5R
BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10µF
Figure 3. Ceramic Capacitor Temperature Characteristics
LT3080
12
3080fc
(5 milliohms for the two devices in parallel) only adds about
10 millivolts of output regulation drop at an output of 2A.
Even with an output voltage as low as 1V, this only adds
1% to the regulation. Of course, more than two LT3080’s
can be paralleled for even higher output current. They are
spread out on the PC board, spreading the heat. Input
resistors can further spread the heat if the input-to-output
difference is high.
Thermal Performance
In this example, two LT3080 3mm × 3mm DFN devices
are mounted on a 1oz copper 4-layer PC board. They are
placed approximately 1.5 inches apart and the board is
mounted vertically for convection cooling. Two tests were
set up to measure the cooling performance and current
sharing of these devices.
The first test was done with approximately 0.7V input-
to-output and 1A per device. This gave a 700 milliwatt
dissipation in each device and a 2A output current. The
temperature rise above ambient is approximately 28°C
and both devices were within plus or minus 1°C. Both the
thermal and electrical sharing of these devices is excel-
lent. The thermograph in Figure 5 shows the temperature
distribution between these devices and the PC board
reaches ambient temperature within about a half an inch
from the devices.
The power is then increased with 1.7V across each device.
This gives 1.7 watts dissipation in each device and a device
temperature of about 90°C, about 65°C above ambient
as shown in Figure 6. Again, the temperature matching
between the devices is within 2°C, showing excellent
tracking between the devices. The board temperature has
reached approximately 40°C within about 0.75 inches of
each device.
While 90°C is an acceptable operating temperature for these
devices, this is in 25°C ambient. For higher ambients, the
temperature must be controlled to prevent device tempera-
ture from exceeding 125°C. A 3-meter-per-second airflow
across the devices will decrease the device temperature
about 20°C providing a margin for higher operating ambi-
ent temperatures.
Both at low power and relatively high power levels de-
vices can be paralleled for higher output current. Current
sharing and thermal sharing is excellent, showing that
acceptable operation can be had while keeping the peak
temperatures below excessive operating temperatures on
a board. This technique allows higher operating current
linear regulation to be used in systems where it could
never be used before.
Quieting the Noise
The LT3080 offers numerous advantages when it comes
to dealing with noise. There are several sources of noise
in a linear regulator. The most critical noise source for any
LDO is the reference; from there, the noise contribution
Figure 6. Temperature Rise at 1.7W Dissipation
Figure 5. Temperature Rise at 700mW Dissipation
applicaTions inForMaTion
LT3080
13
3080fc
from the error amplifier must be considered, and the gain
created by using a resistor divider cannot be forgotten.
Traditional low noise regulators bring the voltage refer-
ence out to an external pin (usually through a large value
resistor) to allow for bypassing and noise reduction of
reference noise. The LT3080 does not use a traditional
voltage reference like other linear regulators, but instead
uses a reference current. That current operates with typi-
cal noise current levels of 3.2pA/√Hz (1nARMS over the
10Hz to 100kHz bandwidth). The voltage noise of this
is equal to the noise current multiplied by the resistor
value. The resistor generates spot noise equal to √4kTR
(k = Boltzmann’s constant, 1.38 10–23 J/°K, and T is
absolute temperature) which is RMS summed with the
reference current noise. To lower reference noise, the
voltage setting resistor may be bypassed with a capacitor,
though this causes start-up time to increase as a factor
of the RC time constant.
The LT3080 uses a unity-gain follower from the SET pin
to drive the output, and there is no requirement to use
a resistor to set the output voltage. Use a high accuracy
voltage reference placed at the SET pin to remove the er-
rors in output voltage due to reference current tolerance
and resistor tolerance. Active driving of the SET pin is
acceptable; the limitations are the creativity and ingenuity
of the circuit designer.
One problem that a normal linear regulator sees with refer-
ence voltage noise is that noise is gained up along with the
output when using a resistor divider to operate at levels
higher than the normal reference voltage. With the LT3080,
the unity-gain follower presents no gain whatsoever from
the SET pin to the output, so noise figures do not increase
accordingly. Error amplifier noise is typically 125nV/√Hz
(40µVRMS over the 10Hz to 100kHz bandwidth); this is
another factor that is RMS summed in to give a final noise
figure for the regulator.
Curves in the Typical Performance Characteristics show
noise spectral density and peak-to-peak noise character-
istics for both the reference current and error amplifier
over the 10Hz to 100kHz bandwidth.
Overload Recovery
Like many IC power regulators, the LT3080 has safe operat-
ing area (SOA) protection. The SOA protection decreases
current limit as the input-to-output voltage increases and
keeps the power dissipation at safe levels for all values
of input-to-output voltage. The LT3080 provides some
output current at all values of input-to-output voltage up
to the device breakdown. See the Current Limit curve in
the Typical Performance Characteristics.
When power is first turned on, the input voltage rises and
the output follows the input, allowing the regulator to start
into very heavy loads. During start-up, as the input voltage
is rising, the input-to-output voltage differential is small,
allowing the regulator to supply large output currents.
With a high input voltage, a problem can occur wherein
removal of an output short will not allow the output volt-
age to recover. Other regulators, such as the LT1085 and
LT1764A, also exhibit this phenomenon so it is not unique
to the LT3080.
The problem occurs with a heavy output load when the
input voltage is high and the output voltage is low. Com-
mon situations are immediately after the removal of a
short circuit. The load line for such a load may intersect
the output current curve at two points. If this happens,
there are two stable operating points for the regulator.
With this double intersection, the input power supply may
need to be cycled down to zero and brought up again to
make the output recover.
Load Regulation
Because the LT3080 is a floating device (there is no ground
pin on the part, all quiescent and drive current is delivered
to the load), it is not possible to provide true remote load
sensing. Load regulation will be limited by the resistance
Figure 7. Connections for Best Load Regulation
+
LT3080
IN
VCONTROL
OUT
3080 F07
SET RSET
RP
PARASITIC
RESISTANCE
RP
RP
LOAD
applicaTions inForMaTion
LT3080
14
3080fc
Table 2. MSE Package, 8-Lead MSOP
COPPER AREA THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE* BACKSIDE BOARD AREA
2500mm22500mm22500mm255°C/W
1000mm22500mm22500mm257°C/W
225mm22500mm22500mm260°C/W
100mm22500mm22500mm265°C/W
*Device is mounted on topside
Table 3. DD Package, 8-Lead DFN
COPPER AREA THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE* BACKSIDE BOARD AREA
2500mm22500mm22500mm260°C/W
1000mm22500mm22500mm262°C/W
225mm22500mm22500mm265°C/W
100mm22500mm22500mm268°C/W
*Device is mounted on topside
Table 4. ST Package, 3-Lead SOT-223
COPPER AREA THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE* BACKSIDE BOARD AREA
2500mm22500mm22500mm248°C/W
1000mm22500mm22500mm248°C/W
225mm22500mm22500mm256°C/W
100mm22500mm22500mm262°C/W
*Device is mounted on topside
Table 5. Q Package, 5-Lead DD-Pak
COPPER AREA THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
TOPSIDE* BACKSIDE BOARD AREA
2500mm22500mm22500mm225°C/W
1000mm22500mm22500mm230°C/W
125mm22500mm22500mm235°C/W
*Device is mounted on topside
T Package, 5-Lead TO-220
Thermal Resistance (Junction-to-Case) = 3°C/W
Calculating Junction Temperature
Example: Given an output voltage of 0.9V, a VCONTROL
voltage of 3.3V ±10%, an IN voltage of 1.5V ±5%, output
current range from 1mA to 1A and a maximum ambient
temperature of 50°C, what will the maximum junction
temperature be for the DFN package on a 2500mm2 board
with topside copper area of 500mm2?
of the connections between the regulator and the load.
The data sheet specification for load regulation is Kelvin
sensed at the pins of the package. Negative side sensing
is a true Kelvin connection, with the bottom of the voltage
setting resistor returned to the negative side of the load
(see Figure 7). Connected as shown, system load regula-
tion will be the sum of the LT3080 load regulation and the
parasitic line resistance multiplied by the output current.
It is important to keep the positive connection between
the regulator and load as short as possible and use large
wire or PC board traces.
Thermal Considerations
The LT3080 has internal power and thermal limiting cir-
cuitry designed to protect it under overload conditions.
For continuous normal load conditions, maximum junc-
tion temperature must not be exceeded. It is important
to give consideration to all sources of thermal resistance
from junction to ambient. This includes junction-to-case,
case-to-heat sink interface, heat sink resistance or circuit
board-to-ambient as the application dictates. Additional
heat sources nearby must also be considered.
For surface mount devices, heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Surface mount heat sinks and plated
through-holes can also be used to spread the heat gener-
ated by power devices.
Junction-to-case thermal resistance is specified from the
IC junction to the bottom of the case directly below the
die. This is the lowest resistance path for heat flow. Proper
mounting is required to ensure the best possible thermal
flow from this area of the package to the heat sinking
material. For the TO-220 package, thermal compound is
strongly recommended for mechanical connections to a
heat sink. A thermally conductive spacer can be used for
electrical isolation as long as the added contribution to
thermal resistance is considered. Note that the Tab or
Exposed Pad (depending on package) is electrically
connected to the output.
The following tables list thermal resistance for several
different copper areas given a fixed board size. All mea-
surements were taken in still air on two-sided 1/16” FR-4
board with one ounce copper.
applicaTions inForMaTion
LT3080
15
3080fc
The power in the drive circuit equals:
PDRIVE = (VCONTROL – VOUT)(ICONTROL)
where ICONTROL is equal to IOUT/60. ICONTROL is a function
of output current. A curve of ICONTROL vs IOUT can be found
in the Typical Performance Characteristics curves.
The power in the output transistor equals:
POUTPUT = (VIN – VOUT)(IOUT)
The total power equals:
PTOTAL = PDRIVE + POUTPUT
The current delivered to the SET pin is negligible and can
be ignored.
VCONTROL(MAX CONTINUOUS) = 3.630V (3.3V + 10%)
VIN(MAX CONTINUOUS) = 1.575V (1.5V + 5%)
VOUT = 0.9V, IOUT = 1A, TA = 50°C
Power dissipation under these conditions is equal to:
PDRIVE = (VCONTROL – VOUT)(ICONTROL)
ICONTROL =IOUT
60 =1A
60 =17mA
PDRIVE = (3.630V – 0.9V)(17mA) = 46mW
POUTPUT = (VIN – VOUT)(IOUT)
POUTPUT = (1.575V – 0.9V)(1A) = 675mW
Total Power Dissipation = 721mW
Junction Temperature will be equal to:
TJ = TA + PTOTALθJA (approximated using tables)
TJ = 50°C + 721mW • 64°C/W = 96°C
In this case, the junction temperature is below the maxi-
mum rating, ensuring reliable operation.
Reducing Power Dissipation
In some applications it may be necessary to reduce
the power dissipation in the LT3080 package without
sacrificing output current capability. Two techniques are
available. The first technique, illustrated in Figure 8, em-
ploys a resistor in series with the regulators input. The
voltage drop across RS decreases the LT3080’s IN-to-OUT
differential voltage and correspondingly decreases the
LT3080’s power dissipation.
As an example, assume: VIN = VCONTROL = 5V, VOUT = 3.3V
and IOUT(MAX) = 1A. Use the formulas from the Calculating
Junction Temperature section previously discussed.
Without series resistor RS, power dissipation in the LT3080
equals:
PTOTAL =5V – 3.3V
( )
1A
60
+5V – 3.3V
( )
1A
=1.73W
If the voltage differential (VDIFF) across the NPN pass
transistor is chosen as 0.5V, then RS equals:
RS=5V – 3.3V
0.5V
1A =1.2
Power dissipation in the LT3080 now equals:
PTOTAL =5V – 3.3V
( )
1A
60
+0.5V
( )
1A =0.53W
The LT3080’s power dissipation is now only 30% compared
to no series resistor. RS dissipates 1.2W of power. Choose
appropriate wattage resistors to handle and dissipate the
power properly.
Figure 8. Reducing Power Dissipation Using a Series Resistor
+
LT3080 IN
VCONTROL
OUT VOUT
VINʹ
VIN
C2
3080 F08
SET
RSET
RS
C1
applicaTions inForMaTion
LT3080
16
3080fc
The second technique for reducing power dissipation,
shown in Figure 9, uses a resistor in parallel with the
LT3080. This resistor provides a parallel path for current
flow, reducing the current flowing through the LT3080.
This technique works well if input voltage is reasonably
constant and output load current changes are small. This
technique also increases the maximum available output
current at the expense of minimum load requirements.
As an example, assume: VIN = VCONTROL = 5V, VIN(MAX) =
5.5V, VOUT = 3.3V, VOUT(MIN) = 3.2V, IOUT(MAX) = 1A and
IOUT(MIN) = 0.7A. Also, assuming that RP carries no more
than 90% of IOUT(MIN) = 630mA.
Calculating RP yields:
RP=
5.5V 3.2V
0.63A =3.65
(5% Standard value = 3.6Ω)
The maximum total power dissipation is (5.5V – 3.2V) •
1A = 2.3W. However the LT3080 supplies only:
1A –
5.5V 3.2V
3.6=0.36A
Therefore, the LT3080’s power dissipation is only:
PDIS = (5.5V – 3.2V) • 0.36A = 0.83W
RP dissipates 1.47W of power. As with the first technique,
choose appropriate wattage resistors to handle and dis-
sipate the power properly. With this configuration, the
LT3080 supplies only 0.36A. Therefore, load current can
increase by 0.64A to 1.64A while keeping the LT3080 in
its normal operating range.
Figure 9. Reducing Power Dissipation Using a Parallel Resistor
+
LT3080 IN
VCONTROL
OUT VOUT
VIN
C2
3080 F09
SET
RSET
RP
C1
applicaTions inForMaTion
LT3080
17
3080fc
Higher Output Current Adding Shutdown
Current Source Low Dropout Voltage LED Driver
+
LT3080
IN
50Ω
MJ4502
VCONTROL
OUT
3080 TA02
SET 4.7µF
332k
VOUT
3.3V
5A
+
1µF
100µF
+
100µF
VIN
6V
+
LT3080
IN
VCONTROL
OUT
100k
3080 TA03
SET
IOUT
0A TO 1A
4.7µF
VIN
10V
1µF +
LT3080 IN
100mA
D1
VCONTROL
OUT
VIN
3080 TA05
SET
R1
24.9k
R2
2.49Ω
C1
+
LT3080
IN
VIN
VCONTROL
OUT VOUT
3080 TA04
SET
1N4148
R1
ON OFF
SHUTDOWN
Q1
VN2222LL
Q2*
VN2222LL
Q2 INSURES ZERO OUTPUT
IN THE ABSENCE OF ANY
OUTPUT LOAD.
*
Using a Lower Value SET Resistor
+
LT3080
IN
1mA
VIN
12V
VCONTROL
OUT
COUT
4.7µF
VOUT
0.5V TO 10V
3080 TA06
SET
R1
49.9k
1%
RSET
10k
R2
499Ω
1%
C1
F
VOUT = 0.5V + 1mA • RSET
Typical applicaTions
LT3080
18
3080fc
Adding Soft-Start
Coincident Tracking
Typical applicaTions
+
LT3080
+
LT3080 ININ
VIN
12V TO 18V
VCONTROL
VCONTROL
OUTOUT
4.7µF 100µF
VOUT
0V TO 10V
3080 TA09
SETSET +
15µF R4
1MEG
100k
0A TO 1A
+
15µF
+
Lab Supply
+
LT3080
IN
VCONTROL
OUT
4.7µF
VOUT3
5V
SET
C3
4.7µF
+
LT3080
IN
VCONTROL
OUT VOUT2
3.3V
3080 TA07
SET
R2
80.6k
169k
C2
4.7µF
C1
1.5µF
+
LT3080
IN
VCONTROL
VIN
7V TO 28V
OUT
SET
R1
249k
VOUT1
2.5V
1A
+
LT3080
IN
VIN
4.8V to 28V
VCONTROL
OUT VOUT
3.3V
1A
COUT
4.7µF
3080 TA08
SET
R1
332k
C2
0.01µF
C1
1µF
D1
1N4148
LT3080
19
3080fc
High Voltage Regulator
Ramp Generator
+
LT3080
6.1V
IN
1N4148
VIN
50V
VCONTROL
OUT VOUT
1A VOUT = 20V
VOUT = 10µA • RSET
3080 TA10
SET
RSET
2MEG
4.7µF
15µF
10µF
BUZ11
10k
+
+
Ground Clamp
Reference Buffer
+
LT3080
IN
VIN
VCONTROL
OUT
4.7µF
VOUT
VEXT
3080 TA13
1N4148
5k
20Ω
1µF
Boosting Fixed Output Regulators
Typical applicaTions
+
LT3080
IN
V
IN
5V
VCONTROL
OUT VOUT
3080 TA11
SET
1N4148
VN2222LL VN2222LL 4.7µF
1µF
1µF
+
LT3080
IN
VIN
VCONTROL
OUT VOUT*
3080 TA12
SET
OUTPUT
INPUT
C1
F
GND
C2
4.7µF
LT1019
*MIN LOAD 0.5mA
3080 TA14
20mΩ
20mΩ
42Ω* 47µF
3.3VOUT
2.6A
33k
*4mV DROP ENSURES LT3080 IS
OFF WITH NO LOAD
MULTIPLE LT3080’S CAN BE USED
+
LT3080
10µF
5V
OUT
SET
LT1963-3.3
LT3080
20
3080fc
Low Voltage, High Current Adjustable High Efficiency Regulator*
Typical applicaTions
2.7V TO 5.5V
100µF 2.2MEG 100k 470pF
10k
1000pF
100µF
294k
12.1k
0.47µH
78.7k
100k
124k
PVIN SW
2N3906
SVIN ITH
RT
VFB
SYNC/MODE
PGOOD
RUN/SS
SGND PGND
LTC3414
+
LT3080
IN
VCONTROL
OUT
SET
+
LT3080
IN
VCONTROL
OUT 0V TO 4V
4A
SET
+
LT3080
IN
VCONTROL
OUT
SET
3080 TA15
+
LT3080
IN
VCONTROL
OUT
100µF
SET
+
+
+
*DIFFERENTIAL VOLTAGE ON LT3080
IS 0.6V SET BY THE VBE OF THE 2N3906 PNP.
20mΩ
20mΩ
20mΩ
20mΩ
MAXIMUM OUTPUT VOLTAGE IS 1.5V
BELOW INPUT VOLTAGE
LT3080
21
3080fc
Adjustable High Efficiency Regulator*
2 Terminal Current Source
Typical applicaTions
3080 TA16
4.5V TO 25V
10µF 100k
0.1µF 68µF
10µH
MBRM140
10k
10k
F
VIN BOOST
SW
FB
SHDN
GND
LT3493
CMDSH-4E
0.1µF
TP0610L
+
LT3080
IN
VCONTROL
OUT
SET 4.7µF
0V TO 10V
1A
*DIFFERENTIAL VOLTAGE ON LT3080
≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD.
1MEG
MAXIMUM OUTPUT VOLTAGE IS 2V
BELOW INPUT VOLTAGE
200k
3080 TA17
R1
100k
+
LT3080
C
COMP
*
IN
VCONTROL
SET
*CCOMP
R1 ≤ 10Ω 10µF
R1 ≥ 10Ω 2.2µF
IOUT = 1V
R1
LT3080
22
3080fc
package DescripTion
3.00 ±0.10
(4 SIDES)
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON TOP AND BOTTOM OF PACKAGE
0.40 ± 0.10
BOTTOM VIEW—EXPOSED PAD
1.65 ± 0.10
(2 SIDES)
0.75 ±0.05
R = 0.125
TYP
2.38 ±0.10
14
85
PIN 1
TOP MARK
(NOTE 6)
0.200 REF
0.00 – 0.05
(DD8) DFN 0509 REV C
0.25 ± 0.05
2.38 ±0.05
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
1.65 ±0.05
(2 SIDES)2.10 ±0.05
0.50
BSC
0.70 ±0.05
3.5 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
DD Package
8-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1698 Rev C)
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LT3080
23
3080fc
package DescripTion
MSOP (MS8E) 0210 REV F
0.53 ± 0.152
(.021 ± .006)
SEATING
PLANE
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
6. EXPOSED PAD DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD
SHALL NOT EXCEED 0.254mm (.010") PER SIDE.
0.18
(.007)
0.254
(.010)
1.10
(.043)
MAX
0.22 – 0.38
(.009 – .015)
TYP
0.86
(.034)
REF
0.65
(.0256)
BSC
0° – 6° TYP
DETAIL “A”
DETAIL “A”
GAUGE PLANE
1 2 34
4.90 ± 0.152
(.193 ± .006)
8
8
1
BOTTOM VIEW OF
EXPOSED PAD OPTION
765
3.00 ± 0.102
(.118 ± .004)
(NOTE 3)
3.00 ± 0.102
(.118 ± .004)
(NOTE 4)
0.52
(.0205)
REF
1.68
(.066)
1.88
(.074)
5.23
(.206)
MIN
3.20 – 3.45
(.126 – .136)
1.68 ± 0.102
(.066 ± .004)
1.88 ± 0.102
(.074 ± .004)
0.889 ± 0.127
(.035 ± .005)
RECOMMENDED SOLDER PAD LAYOUT
0.42 ± 0.038
(.0165 ± .0015)
TYP
0.65
(.0256)
BSC
0.1016 ± 0.0508
(.004 ± .002)
MS8E Package
8-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1662 Rev F)
DETAIL “B”
DETAIL “B”
CORNER TAIL IS PART OF
THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
NO MEASUREMENT PURPOSE
0.05 REF
0.29
REF
MS8E Package
8-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1662 Rev F)
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LT3080
24
3080fc
Q Package
5-Lead Plastic DD-Pak
(Reference LTC DWG # 05-08-1461)
package DescripTion
Q(DD5) 0502
.028 – .038
(0.711 – 0.965)
TYP
.143 +.012
–.020
( )
3.632+0.305
–0.508
.067
(1.702)
BSC
.013 – .023
(0.330 – 0.584)
.095 – .115
(2.413 – 2.921)
.004 +.008
–.004
( )
0.102+0.203
–0.102
.050 ± .012
(1.270 ± 0.305)
.059
(1.499)
TYP
.045 – .055
(1.143 – 1.397)
.165 – .180
(4.191 – 4.572)
.330 – .370
(8.382 – 9.398)
.060
(1.524)
TYP
.390 – .415
(9.906 – 10.541)
15° TYP
.420
.350
.565
.090
.042
.067
RECOMMENDED SOLDER PAD LAYOUT
.325
.205
.080
.565
.090
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
.042
.067
.420
.276
.320
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.300
(7.620)
.075
(1.905)
.183
(4.648)
.060
(1.524)
.060
(1.524)
.256
(6.502)
BOTTOM VIEW OF DD-PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LT3080
25
3080fc
package DescripTion
T Package
5-Lead Plastic TO-220 (Standard)
(Reference LTC DWG # 05-08-1421)
T5 (TO-220) 0801
.028 – .038
(0.711 – 0.965)
.067
(1.70) .135 – .165
(3.429 – 4.191)
.700 – .728
(17.78 – 18.491)
.045 – .055
(1.143 – 1.397)
.095 – .115
(2.413 – 2.921)
.013 – .023
(0.330 – 0.584)
.620
(15.75)
TYP
.155 – .195*
(3.937 – 4.953)
.152 – .202
(3.861 – 5.131)
.260 – .320
(6.60 – 8.13)
.165 – .180
(4.191 – 4.572)
.147 – .155
(3.734 – 3.937)
DIA
.390 – .415
(9.906 – 10.541)
.330 – .370
(8.382 – 9.398)
.460 .500
(11.684 12.700)
.570 – .620
(14.478 – 15.748)
.230 – .270
(5.842 – 6.858)
BSC
SEATING PLANE
* MEASURED AT THE SEATING PLANE
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LT3080
26
3080fc
package DescripTion
ST Package
3-Lead Plastic SOT-223
(Reference LTC DWG # 05-08-1630)
.114 – .124
(2.90 – 3.15)
.248 – .264
(6.30 – 6.71)
.130 – .146
(3.30 – 3.71)
.264 – .287
(6.70 – 7.30)
.0905
(2.30)
BSC
.033 – .041
(0.84 – 1.04)
.181
(4.60)
BSC
.024 – .033
(0.60 – 0.84)
.071
(1.80)
MAX
10°
MAX
.012
(0.31)
MIN
.0008 – .0040
(0.0203 – 0.1016)
10° – 16°
.010 – .014
(0.25 – 0.36)
10° – 16°
RECOMMENDED SOLDER PAD LAYOUT
ST3 (SOT-233) 0502
.129 MAX
.059 MAX
.059 MAX
.181 MAX
.039 MAX
.248 BSC
.090
BSC
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
LT3080
27
3080fc
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
B 6/10 Made minor updates to Features and Description sections
Revised Line Regulation Conditions and Note 2
Made minor text edits in Applications Information section
Added 200k resistor to drawing 3080 TA19 in Typical Applications section
Updated Package Description drawings
1
3
9
20
21, 22
C 9/11 Added I-grade information to the Absolute Maximum Ratings section and the Order Information table.
Updated Note 2.
2
3
(Revision history begins at Rev B)
LT3080
28
3080fc
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
LINEAR TECHNOLOGY CORPORATION 2007
LT 0911 REV C • PRINTED IN USA
PART NUMBER DESCRIPTION COMMENTS
LDOs
LT1086 1.5A Low Dropout Regulator Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output
LT1117 800mA Low Dropout Regulator 1V Dropout, Adjustable or Fixed Output, DD-Pak, SOT-223 Packages
LT1118 800mA Low Dropout Regulator OK for Sinking and Sourcing, S0-8 and SOT-223 Packages
LT1963A 1.5A Low Noise, Fast Transient Response LDO 340mV Dropout Voltage, Low Noise: 40µVRMS, VIN = 2.5V to 20V,
TO-220, DD-Pak, SOT-223 and SO-8 Packages
LT1965 1.1A Low Noise LDO 290mV Dropout Voltage, Low Noise 40µVRMS, VIN = 1.8V to 20V,
VOUT = 1.2V to 19.5V, Stable with Ceramic Caps TO-220, DD-Pak,
MSOP and 3mm × 3mm DFN packages.
LTC
®
3026 1.5A Low Input Voltage VLDO
TM
Regulator VIN: 1.14V to 3.5V (Boost Enabled), 1.14V to 5.5V (with External 5V),
VDO = 0.1V, IQ = 950µA, Stable with 10µF Ceramic Capacitors, 10-Lead
MSOP and DFN Packages
Switching Regulators
LT1976 High Voltage, 1.5A Step-Down Switching Regulator f = 200kHz, IQ = 100µA, TSSOP-16E Package
LTC3414 4A (IOUT), 4MHz Synchronous Step-Down DC/DC
Converter
95% Efficiency, VIN: 2.25V to 5.5V, VOUT(MIN) = 0.8V, TSSOP Package
LTC3406/LTC3406B 600mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC
Converter
95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN) = 0.6V, IQ = 20µA,
ISD < 1µA, ThinSOT
TM
Package
LTC3411 1.25A (IOUT), 4MHz Synchronous Step-Down DC/DC
Converter
95% Efficiency, VIN: 2.5V to 5.5V, VOUT(MIN) = 0.8V, IQ = 60µA,
ISD < 1µA, 10-Lead MS or DFN Packages
Paralleling Regulators
relaTeD parTs
Typical applicaTion
+
LT3080
IN
VIN
4.8V TO 28V
VCONTROL
OUT 20mΩ
10µF
VOUT
3.3V
2A
3080 TA18
165k
SET
1µF
+
LT3080
IN
VCONTROL
OUT 20mΩ
SET

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