LT3080EDD#PBF - LINEAR TECHNOLOGY

LT3080

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

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

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

OUT

DD PACKAGE

8-LEAD (3mm × 3mm) PLASTIC DFN

1OUT

OUT

SET

VCONTROL

TJMAX = 125°C, θJA = 64°C/W, θJC = 3°C/W

EXPOSED PAD (PIN 9) IS OUT, MUST BE SOLDERED TO PCB

OUT

SET

VCONTROL

TOP VIEW

MS8E PACKAGE

8-LEAD PLASTIC MSOP

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

VCONTROL

OUT

SET

TJMAX = 125°C, θJA = 30°C/W, θJC = 3°C/W

T PACKAGE

5-LEAD PLASTIC TO-220

VCONTROL

OUT

SET

FRONT VIEW

TAB IS

OUT

TJMAX = 125°C, θJA = 40°C/W, θJC = 3°C/W

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

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

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)

9.90

9.80

10.10

10.20

µA

Output Offset Voltage (VOUT – VSET)

VIN = 1V, VCONTROL = 2V, IOUT = 1mA

VOS DFN and MSOP Package

–2

–3.5

3.5

SOT-223, DD-Pak and T0-220 Package

–5

–6

Load Regulation ΔISET

ΔVOS

ΔILOAD = 1mA to 1.1A

ΔILOAD = 1mA to 1.1A (Note 8)

–0.1

0.6

1.3

Line Regulation (Note 9)

DFN and MSOP Package ΔISET

ΔVOS

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

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)

300 500

µA

VCONTROL Dropout Voltage (Note 4) ILOAD = 100mA

ILOAD = 1.1A

1.2

1.35

1.6

VIN Dropout Voltage (Note 4) ILOAD = 100mA

ILOAD = 1.1A

100

350

200

500

VCONTROL Pin Current ILOAD = 100mA

ILOAD = 1.1A

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

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

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)

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)

3080 G04

–1 01

–2

N = 13250

INPUT-TO-OUTPUT VOLTAGE (V)

OFFSET VOLTAGE (mV)

–0.25

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)

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

0.25

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

–0.5

–0.3

–0.7

–0.1

–20

–40

–60

–30

–10

–50

∆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)

MINIMUM IN VOLTAGE (VIN – VOUT) (mV)

150

200

250

0.6 1.0

3080 G09

100

00.2 0.4 0.8

300

350

400

1.2

TJ = 25°C

TJ = 125°C

Offset Voltage Distribution

Typical perForMance characTerisTics

LT3080

3080fc

Typical perForMance characTerisTics

TIME (µs)

OUTPUT VOLTAGE

DEVIATION (mV)LOAD CURRENT (mA)

–25

3080 G15

400

200

–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

350 ILOAD = 1.1A

ILOAD = 500mA

ILOAD = 100mA

OUTPUT CURRENT (A)

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)

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)

OUTPUT VOLTAGE

DEVIATION (mV)LOAD CURRENT (A)

–50

150

3080 G16

1.2

0.6

–100

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)

IN/CONTROL VOLTAGE (V)

OUTPUT VOLTAGE

DEVIATION (mV)

–25

3080 G17

–50

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)

OUTPUT VOLTAGE (V) INPUT VOLTAGE (V)

3080 G18

2.0

1.0

1.5

0.5

021 43 6 7 9

510

RSET = 100k

CSET = 0

RLOAD = 1Ω

COUT = 2.2µF CERAMIC

LT3080

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)

CONTROL PIN CURRENT (mA)

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)

CONTROL PIN CURRENT (mA)

0.2 0.4 0.6 0.8

3080 G20

1.0 1.2

VCONTROL – VOUT = 2V

VIN – VOUT = 1V

TJ = –50°C

TJ = 125°C

TJ = 25°C

RTEST (Ω)

OUTPUT VOLTAGE (V)

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

3080 G21

2k1k

VIN = 20V

VIN = 5V

SET PIN = 0V

VIN VOUT

RTEST

VIN = 10V

FREQUENCY (Hz)

RIPPLE REJECTION (dB)

100

10k 100k10010 1k 1M

3080 G22

VIN = VCONTROL = VOUT (NOMINAL) + 2V

RIPPLE = 50mVP-P

COUT = 2.2µF CERAMIC

ILOAD = 100mA

ILOAD = 1.1A

FREQUENCY (Hz)

RIPPLE REJECTION (dB)

100

10k 100k10010 1k 1M

3080 G23

VIN = VOUT (NOMINAL) + 1V

VCONTROL = VOUT (NOMINAL) +2V

COUT = 2.2µF CERAMIC

RIPPLE = 50mVP-P

ILOAD = 100mA

ILOAD = 1.1A

FREQUENCY (Hz)

RIPPLE REJECTION (dB)

100

10k 100k10010 1k 1M

3080 G24

VIN = VOUT (NOMINAL) + 1V

VCONTROL = VOUT (NOMINAL) +2V

RIPPLE = 50mVP-P

COUT = 2.2µF CERAMIC

ILOAD = 1.1A

TEMPERATURE (°C)

–50

RIPPLE REJECTION (dB)

050 75

3080 G25

–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)

ERROR AMPLIFIER NOISE

SPECTRAL DENSITY (nV/√Hz)

REFERENCE CURRENT NOISE

SPECTRAL DENSITY (pA/ √Hz)

10k

10k 100k10010 1k

3080 G26

100

0.1

1.0

100

LT3080

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

10k 100k10010 1k 1M

3080 G28

–20

–15

–25

–5

–200

300

–100

100

200

–50

250

–150

150

IL = 1.1A

IL = 100mA

IL = 1.1A

LT3080

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

10µA

3080 BD

OUTSET

block DiagraM

applicaTions inForMaTion

LT3080

3080fc

Figure 1. Basic Adjustable Regulator

–

LT3080

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

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

4.8V TO 28V

VOUT

3.3V

VCONTROL

OUT

10µF

1µF

SET

165k

3080 F04

10mΩ

Figure 4. Parallel Devices

applicaTions inForMaTion

DC BIAS VOLTAGE (V)

CHANGE IN VALUE (%)

3080 F02

–20

–40

–60

–80

–100 04810

2 6 12 14

X5R

Y5V

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

Figure 2. Ceramic Capacitor DC Bias Characteristics

TEMPERATURE (°C)

–50

–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

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

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

VCONTROL

OUT

3080 F07

SET RSET

PARASITIC

RESISTANCE

LOAD

applicaTions inForMaTion

LT3080

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

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 + PTOTAL • θJA (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 regulator’s 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









+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 =1.2Ω

Power dissipation in the LT3080 now equals:

PTOTAL =5V – 3.3V

( )

•1A









+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

3080 F08

SET

RSET

applicaTions inForMaTion

LT3080

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 =3.65Ω

(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

3.6Ω=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

3080 F09

SET

RSET

applicaTions inForMaTion

LT3080

3080fc

Higher Output Current Adding Shutdown

Current Source Low Dropout Voltage LED Driver

–

LT3080

50Ω

MJ4502

VCONTROL

OUT

3080 TA02

SET 4.7µF

332k

VOUT

3.3V

1µF

100µF

VIN

–

LT3080

VCONTROL

OUT 1Ω

100k

3080 TA03

SET

IOUT

0A TO 1A

4.7µF

VIN

10V

1µF +

–

LT3080 IN

100mA

VCONTROL

OUT

VIN

3080 TA05

SET

24.9k

2.49Ω

–

LT3080

VIN

VCONTROL

OUT VOUT

3080 TA04

SET

1N4148

ON OFF

SHUTDOWN

VN2222LL

Q2*

VN2222LL

Q2 INSURES ZERO OUTPUT

IN THE ABSENCE OF ANY

OUTPUT LOAD.

Using a Lower Value SET Resistor

–

LT3080

1mA

VIN

12V

VCONTROL

OUT

COUT

4.7µF

VOUT

0.5V TO 10V

3080 TA06

SET

49.9k

RSET

10k

499Ω

1µF

VOUT = 0.5V + 1mA • RSET

Typical applicaTions

LT3080

3080fc

Adding Soft-Start

Coincident Tracking

Typical applicaTions

–

LT3080

–

LT3080 ININ

VIN

12V TO 18V

VCONTROL

OUTOUT

4.7µF 100µF

VOUT

0V TO 10V

3080 TA09

SETSET +

15µF R4

1MEG

1Ω

100k

0A TO 1A

15µF

Lab Supply

–

LT3080

VCONTROL

OUT

4.7µF

VOUT3

SET

4.7µF

–

LT3080

VCONTROL

OUT VOUT2

3.3V

3080 TA07

SET

80.6k

169k

4.7µF

1.5µF

–

LT3080

VCONTROL

VIN

7V TO 28V

OUT

SET

249k

VOUT1

2.5V

–

LT3080

VIN

4.8V to 28V

VCONTROL

OUT VOUT

3.3V

COUT

4.7µF

3080 TA08

SET

332k

0.01µF

1µF

1N4148

LT3080

3080fc

High Voltage Regulator

Ramp Generator

–

LT3080

6.1V

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

VIN

VCONTROL

OUT

4.7µF

VOUT

VEXT

3080 TA13

1N4148

20Ω

1µF

Boosting Fixed Output Regulators

Typical applicaTions

–

LT3080

VCONTROL

OUT VOUT

3080 TA11

SET

1N4148

VN2222LL VN2222LL 4.7µF

1µF

–

LT3080

VIN

VCONTROL

OUT VOUT*

3080 TA12

SET

OUTPUT

INPUT

1µF

GND

4.7µF

LT1019

*MIN LOAD 0.5mA

3080 TA14

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

OUT

SET

LT1963-3.3

LT3080

3080fc

Low Voltage, High Current Adjustable High Efﬁciency Regulator*

Typical applicaTions

2.7V TO 5.5V†

2×

100µF 2.2MEG 100k 470pF

10k

1000pF

2×

100µF

294k

12.1k

0.47µH

78.7k

100k

124k

PVIN SW

2N3906

SVIN ITH

VFB

SYNC/MODE

PGOOD

RUN/SS

SGND PGND

LTC3414

–

LT3080

VCONTROL

OUT

SET

–

LT3080

VCONTROL

OUT 0V TO 4V†

SET

–

LT3080

VCONTROL

OUT

SET

3080 TA15

–

LT3080

VCONTROL

OUT

100µF

SET

*DIFFERENTIAL VOLTAGE ON LT3080

IS 0.6V SET BY THE VBE OF THE 2N3906 PNP.

20mΩ

†MAXIMUM OUTPUT VOLTAGE IS 1.5V

BELOW INPUT VOLTAGE

LT3080

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

1µF

VIN BOOST

SHDN

GND

LT3493

CMDSH-4E

0.1µF

TP0610L

–

LT3080

VCONTROL

OUT

SET 4.7µF

0V TO 10V†

*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

100k

–

LT3080

COMP

VCONTROL

SET

*CCOMP

R1 ≤ 10Ω 10µF

R1 ≥ 10Ω 2.2µF

IOUT = 1V

LT3080

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

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

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”

GAUGE PLANE

1 2 34

4.90 ± 0.152

(.193 ± .006)

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”

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

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

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

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

.181 MAX

.039 MAX

.248 BSC

.090

BSC

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

LT3080

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

21, 22

C 9/11 Added I-grade information to the Absolute Maximum Ratings section and the Order Information table.

Updated Note 2.

(Revision history begins at Rev B)

LT3080

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

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

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

VIN

4.8V TO 28V

VCONTROL

OUT 20mΩ

10µF

VOUT

3.3V

3080 TA18

165k

SET

1µF

–

LT3080

VCONTROL

OUT 20mΩ

SET