LINEAR TECHNOLOGY LT3080 Technical data

FEATURES

prop

LT3080

Adjustable1.1A Single

Resistor Low Dropout

Regulator

U

DESCRIPTIO

■

Outputs May be Paralleled for Higher Current and

Heat Spreading

■

Output Current: 1.1A

■

Single Resistor Programs Output Voltage

■

1% Initial Accuracy of SET Pin Current

■

Output Adjustable to 0V

■

Low Output Noise: 40μV

■

Wide Input Voltage Range: 1.2V to 36V

■

Low Dropout Voltage: 300mV

■

<1mV Load Regulation

■

<0.001%/V Line Regulation

■

Minimum Load Current: 0.5mA

■

Stable with 2.2μF Minimum Ceramic Output

(10Hz to 100kHz)

RMS

Capacitor

■

Current Limit with Foldback and Overtemperature

Protected

■

Available in 8-Lead MSOP, 3mm × 3mm DFN,

5-Lead TO-220 and 3-Lead SOT-223

U

APPLICATIO S

■

High Current All Surface Mount Supply

■

High Effi ciency Linear Regulator

■

Post Regulator for Switching Supplies

■

Low Parts Count Variable Voltage Supply

■

Low Output Voltage Power Supplies

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 cur­rent 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 300 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 TO-220 and
a simple-to-use 3-lead SOT-223 version.

, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other

trademarks are the

erty of their respective owners.

TYPICAL APPLICATIO

Variable Output Voltage 1.1A Supply

SET

LT3080

R

SET

V

OUT

+
–

V

1.2V TO 36V
V

CONTROL

1μF

IN

IN

= R

SET

U

• 10μA

OUT

3080 TA01a

V

OUT

2.2μF

Set Pin Current Distribution

N = 13792

9.80

9.90

SET PIN CURRENT DISTRIBUTION (μA)

10.00

10.10

3080 G02

10.20

3080f

1

LT3080

(

WW

W

ABSOLUTE AXI U RATI GS

V

CONTROL

Pin Voltage ..................................... 40V, –0.3V

U

(Note 1)(All Voltages Relative to V

IN Pin Voltage ................................................ 40V, –0.3V

SET Pin Current (Note 7) .....................................±10mA

SET Pin Voltage (Relative to OUT) .........................±0.3V

Output Short-Circuit Duration .......................... Indefi nite

PIN CONFIGURATION

TOP VIEW

1OUT

OUT

2

OUT

3

SET

4

8-LEAD

T

= 125°C, θJA = 64°C/W, θJC = 3°C/W

JMAX

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

9

DD PACKAGE

3mm × 3mm) PLASTIC DFN

8
7

6
5

IN
IN
NC
V

CONTROL

)

OUT

Operating Junction Temperature Range

(Notes 2, 10) .......................................... –40°C to 125°C

Storage Temperature Range: .................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec)

MS8E, T and ST Packages Only ........................ 300°C

TOP VIEW

8

OUT

1

OUT

2

OUT

SET

T

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

8-LEAD PLASTIC MSOP

= 125°C, θJA = 60°C/W, θJC = 10°C/W

JMAX

9

3
4

MS8E PACKAGE

IN

7

IN

6

NC

5

V

CONTROL

FRONT VIEW

3

IN*

TAB IS

OUT

ST PACKAGE

3-LEAD PLASTIC SOT-223

AND IN TIED TOGETHER

CONTROL

= 125°C, θJA = 55°C/W, θJC = 15°C/W

JMAX

2

OUT

1

SET

TAB IS

OUT

FRONT VIEW

5
4
3
2
1

T PACKAGE

5-LEAD PLASTIC TO-220

T

= 125°C, θJA = 40°C/W, θJC = 3°C/W

JMAX

IN
V

CONTROL

OUT
SET
NC

*IN IS V

T

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE

LT3080EDD#PBF LT3080EDD#TRPBF LCBN 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C
LT3080EMS8E#PBF LT3080EMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C
LT3080ET#PBF LT3080ET#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

LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE

LT3080EDD LT3080EDD#TR LCBN 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C
LT3080EMS8E LT3080EMS8E#TR LTCBM 8-Lead Plastic MSOP –40°C to 125°C
LT3080ET LT3080ET#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
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/

3080f

2

LT3080

The ● denotes the specifi cations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise specifi cations are at T

PARAMETER CONDITIONS MIN TYP MAX UNITS

SET Pin Currrent I

Output Offset Voltage (V
V

= 1V, V

IN

CONTROL

= 2V, I

OUT

OUT

– V

= 1mA

SET

)

V

Load Regulation ΔI

ΔV

Line Regulation (Note 9)
DFN and MSOP Package

Line Regulation (Note 9)
SOT-223 and TO-220 Package

ΔI
ΔV

ΔI
ΔV

Minimum Load Current (Notes 3, 9) VIN = V

V

Dropout Voltage (Note 4) I

CONTROL

VIN Dropout Voltage (Note 4) I

CONTROL Pin Current I

Current Limit VIN = 5V, V
Error Amplifi er RMS Output Noise (Note 6) I
Reference Current RMS Output Noise (Note 6) 10Hz ≤ f ≤ 100kHz 1 nA
Ripple Rejection f = 120Hz, V

Thermal Regulation, I

SET

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 specifi ed, all voltages are with respect to V
The LT3080 is tested and specifi ed under pulse load conditions such that
T

≈ TA. The LT3080 is 100% tested at TA = 25°C. Performance at –40°C

J

and 125°C is assured by design, characterization and correlation with
statistical process controls.

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 (V

) or minimum input voltage (VIN). Both parameters are

CONTROL

specifi ed with respect to the output voltage. The specifi cations represent the
minimum input-to-output differential voltage required to maintain regulation.

Note 5: The CONTROL 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

VIN = 1V, V

SET

V

≥ 1V, V

IN

DFN and MSOP Package

OS

SOT-223 and T0-220 Package

ΔI

SET

SET

SET

OS

LOAD =

ΔI

OS

LOAD =

VIN = 1V to 25V, V
V

OS

IN

VIN = 1V to 26V, V
V

IN

V

IN

V

IN

LOAD

I

LOAD

LOAD

I

LOAD

LOAD

I

LOAD

LOAD

= 1V to 25V, V

= 1V to 26V, V

= V
= V

f = 10kHz
f = 1MHz

10ms Pulse 0.003 %/W

= 25°C. (Note 11)

A

CONTROL
CONTROL

= 2.0V, I
≥ 2.0V, 1mA ≤ I

= 1mA, TJ = 25°C

LOAD

1mA to 1.1A
1mA to 1.1A (Note 8)

=1V to 25V, I

CONTROL

=1V to 25V, I

CONTROL

=1V to 26V, I

CONTROL

=1V to 26V, I

CONTROL

= 10V

CONTROL

= 25V (DFN and MSOP Package)

CONTROL

= 26V (SOT-223 and TO-220 Package)

CONTROL

= 100mA
= 1.1A

= 100mA
= 1.1A

= 100mA
= 1.1A

CONTROL

= 5V, V

SET

= 0V, V

= 1.1A, 10Hz ≤ f ≤ 100kHz, C

RIPPLE

= 0.5V

P-P

, I

LOAD

= 0.2A, C

resistor shot noise and reference current noise; output noise is then equal
to error amplifi er noise (see Applications Information section).

Note 7: SET pin is clamped to the output with diodes. These diodes only
carry current under transient overloads.

.

OUT

Note 8: Load regulation is Kelvin sensed at the package.
Note 9: Current limit may decrease to zero at input-to-output differential

voltages (V
(SOT-223 and TO-220 package). Operation at voltages for both IN and
V

CONTROL

between input and output voltage is below the specifi ed differential (V
V

OUT

when the device is in current limit.
Note 10: This IC includes over-temperature protection that is intended

to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature
when over-temperature protection is active. Continuous operation above
the specifi ed maximum operating junction temperature may impair device
reliability.

Note 11: The SOT-223 package connects the IN and V
together internally. Therefore, test conditions for this pin follow the
V

CONTROL

≤ 1.1A (Note 9)

LOAD

●

●

●

9.90

9.801010
–2

–3.5

–5
–6

10.10

10.20
2

3.5
5

6

–0.1

LOAD
LOAD

LOAD
LOAD

=1mA
=1mA

=1mA
=1mA

●

●

●

●

●

●

0.6 1.3

0.1

0.003

0.1

0.003
300 500

0.5 nA/V

0.5 nA/V

1
1

1.2

OUT

= 10μF, C

OUT

= –0.1V

SET

= 0.1μF, C

SET

●

●

●

●

●

●

= 0.1μF 40 μV

= 2.2μF

OUT

1.35 1.6
100

350

17

200
500

4

6

30

1.1 1.4 A

75
55
20

) greater than 25V (DFN and MSOP package) or 26V

IN–VOUT

is allowed up to a maximum of 36V as long as the difference

) voltage. Line and load regulation specifi cations are not applicable

pins

CONTROL

conditions listed in the Electrical Characteristics Table.

μA
μA

mV
mV

mV
mV

nA

mV

mV/V

mV/V

μA
mA
mA

mV
mV

mA
mA

RMS

RMS

dB

dB

dB

–

IN

3080f

V
V

3

LT3080

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Set Pin Current

10.20

10.15

10.10

10.05

10.00

9.95

SET PIN CURRENT (μA)

9.90

9.85

9.80
–50

–25

0

50

25

TEMPERATURE (°C)

75

100

125

150

3080 G01

Offset Voltage Distribution

N = 13250

–2

–1

VOS DISTRIBUTION (mV)

Load Regulation Minimum Load Current

0

ΔI

= 1mA TO 1.1A

LOAD

– V

V

–0.1

IN

OUT

–0.2

–0.3

–0.4

–0.5

–0.6

–0.7

CHANGE IN OFFSET VOLTAGE WITH LOAD (mV)

–0.8

CHANGE IN REFERENCE CURRENT

CHANGE IN OFFSET VOLTAGE

–50

–25

0

0

= 2V

(V

– V

OUT

25

TEMPERATURE (°C)

)

SET

50

75

100

125

3080 G04

3080 G07

2

CHANGE IN REFERENCE CURRENT WITH LOAD (nA)

20

10

0

–10

–20

–30

–40

–50

–60

150

1

Set Pin Current Distribution Offset Voltage (V

N = 13792

9.80

9.90

SET PIN CURRENT DISTRIBUTION (μA)

Offset Voltage Offset Voltage

1.00
I

= 1mA

LOAD

0.75

0.50

0.25

0

–0.25

OFFSET VOLTAGE (mV)

–0.50

–0.75

–1.00

0.8

0.7

0.6

0.5

0.4

0.3

0.2

MINIMUM LOAD CURRENT (mA)

0.1

612 24

0

INPUT-TO-OUTPUT VOLTAGE (V)

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

V

IN, CONTROL

V

IN, CONTROL

0

–50

–25

0

25

TEMPERATURE (°C)

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

– V

– V

10.00

18

OUT

OUT

50

= 36V*

= 1.5V

75

10.10

100

– V

2.0

OUT

IL = 1mA

1.5

1.0

0.5

0

–0.5

OFFSET VOLTAGE (mV)

–1.0

–1.5

36*

–2.0

–50

0.25

0

–0.25

–0.50

–0.75

–1.00

OFFSET VOLTAGE (mV)

–1.25

–1.50

–1.75

–25

0

TEMPERATURE (°C)

TJ = 125°C

0.2 0.4 0.8

0

LOAD CURRENT (A)

25

TJ = 25°C

50

0.6

10.20

3080 G02

30

3080 G05

)

SET

75

100

1.0

125

150

3080 G03

1.2

3080 G06

Dropout Voltage (Minimum IN
Voltage)

400

350

125

3080 G08

150

) (mV)

OUT

300

– V

250

IN

200

150

100

50

MINIMUM IN VOLTAGE (V

0

0.2 0.4 0.8

0

OUTPUT CURRENT (A)

TJ = 125°C

0.6

TJ = 25°C

1.0

1.2

3080 G09

4

3080f

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LT3080

Dropout Voltage (Minimum IN
Voltage)

400

350

) (mV)

OUT

300

– V

IN

250

I

200

150

100

50

MINIMUM IN VOLTAGE (V

0

–25

–50

0

TEMPERATURE (°C)

LOAD

I

LOAD

50

25

Current Limit

1.6

1.4

1.2

VIN = 7V

1.0

0.8

0.6

CURRENT LIMIT (A)

0.4

0.2

0

–50

V

–25

OUT

= 0V

0

50

25

TEMPERATURE (°C)

I

LOAD

= 500mA

= 100mA

75

75

= 1.1A

100

100

125

125

3080 G10

3080 G13

150

150

Dropout Voltage (Minimum

Pin Voltage)

TJ = –50°C

TJ = 25°C

0.2 0.4 0.8

0.6

OUTPUT CURRENT (A)

) (V)

1.6

OUT

1.4

– V

1.2

CONTROL

1.0

0.8

0.6

0.4

0.2

0

MINIMUM CONTROL VOLTAGE (V

V

CONTROL

0

Current Limit

1.6

1.4

1.2

1.0

0.8

0.6

CURRENT LIMIT (A)

MSOP

0.4

0.2

0

612 24

0

INPUT-TO-OUTPUT DIFFERENTIAL (V)

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

SOT-223
AND
TO-220

AND

DFN

18

TJ = 125°C

TJ = 25°C

1.0

30

3080 G11

3080 G14

1.2

36*

Dropout Voltage (Minimum

) (V)

1.6

OUT

1.4

– V

1.2

CONTROL

1.0

0.8

0.6

0.4

0.2

0

MINIMUM CONTROL VOLTAGE (V

–50

V

CONTROL

–25

0

Pin Voltage)

I

= 1mA

LOAD

50

25

TEMPERATURE (°C)

Load Transient Response

75

50

25

0

–25

–50

OUTPUT VOLTAGE DEVIATION (mV)LOAD CURRENT (mA)

400

300

200

100

C

OUT

0

105

0

C

OUT

= 2.2μF CERAMIC

2015

25

TIME (μs)

I

= 1.1A

LOAD

75

100

V

= 1.5V

OUT

= 0.1μF

C

SET

= V

V

IN

CONTROL

= 10μF CERAMIC

30 35 45

40

125

150

3080 G12

= 3V

50

3080 G15

Load Transient Response Line Transient Response

150

100

50

0

–50

–100

OUTPUT VOLTAGE DEVIATION (mV)LOAD CURRENT (A)

1.2

0.9

0.6

0.3

0

105

0

VIN = V
V
C
C

2015

25

TIME (μs)

CONTROL

= 1.5V

OUT

= 10μF CERAMIC

OUT

= 0.1μF

SET

30 35 45

40

= 3V

50

3080 G16

75

50

25

0

–25

–50

6

5

4

3

2

2010

0

IN/CONTROL VOLTAGE (V) OUTPUT VOLTAGE DEVIATION (mV)

4030

50

TIME (μs)

V

= 1.5V

OUT

= 10mA

I

LOAD

= 2.2μF

C

OUT

CERAMIC

= 0.1μF

C

SET

CERAMIC

60 70 90

80

3080 G17

100

Turn-On Response

5

4

3

2

1

0

2.0

1.5

1.0

0.5

0

OUTPUT VOLTAGE (V) INPUT VOLTAGE (V)

21

0

C

= 2.2μF CERAMIC

OUT

43

5

TIME (μs)

R

= 100k

SET

= 0

C

SET

= 1Ω

R

LOAD

67 9

8

3080 G27

3080f

5

10

LT3080

UW

TYPICAL PERFOR A CE CHARACTERISTICS

V

CONTROL

25

20

15

10

CONTROL PIN CURRENT (mA)

5

0

0

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

Pin Currrent

I

= 1.1A

LOAD

DEVICE IN
CURRENT LIMIT

I

= 1mA

LOAD

12 18 24

6

INPUT-TO-OUTPUT DIFFERENTIAL (V)

Ripple Rejection - Single Supply

100

VIN = V

90

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

10

= 2.2μF CERAMIC

C

OUT

0

CONTROL

I

= 1.1A

LOAD

FREQUENCY (Hz)

= V

OUT (NOMINAL)

RIPPLE = 50mV

10k 100k10010 1k 1M

I

LOAD

30 36*

+ 2V

= 100mA

3080 G18

P–P

3080 G21

V

CONTROL

30

V
V

25

20

15

10

CONTROL PIN CURRENT (mA)

5

0

0

Ripple Rejection - Dual Supply

- V

100

90

80

70

60

50

40

VIN = V
V

30

RIPPLE REJECTION (dB)

C

20

10

0

Pin Current

– V

CONTROL

– V

= 1V

IN

OUT

0.4 0.6 0.8

0.2
LOAD CURRENT (A)

Pin

CONTROL

I

LOAD

OUT (NOMINAL)

= V

CONTROL

= 2.2μF CERAMIC

OUT

RIPPLE = 50mV

= 2V

OUT

TJ = –50°C

= 125°C

T

J

= 1.1A

+ 1V

OUT (NOMINAL)

P–P

FREQUENCY (Hz)

+2V

10k 100k10010 1k 1M

I

LOAD

T

J

= 25°C

1.0 1.2

3080 G19

= 100mA

3080 G22

Residual Output Voltage with
Less Than Minimum Load

0.8
SET PIN = 0V

0.7

0.6

0.5

0.4

0.3

OUTPUT VOLTAGE (V)

0.2

0.1

0

V

IN

V

= 10V

IN

0

V

OUT

R

TEST

= 5V

V

IN

R

(Ω)

TEST

Ripple Rejection - Dual Supply

- IN Pin

100

90

80

70

60

50

VIN = V

40

30

RIPPLE REJECTION (dB)

20

10

V

CONTROL

RIPPLE = 50mV

C

= 2.2μF CERAMIC

OUT

= 1.1A

I

LOAD

0

OUT (NOMINAL)

= V

+ 1V

OUT (NOMINAL)

P–P

FREQUENCY (Hz)

+2V

10k 100k10010 1k 1M

VIN = 20V

2k1k

3080 G20

3080 G23

6

Ripple Rejection (120Hz)

80

79

78

77

76

75

74

73

RIPPLE REJECTION (dB)

72

71

70

–50

SINGLE SUPPLY OPERATION

= V

V

IN

RIPPLE = 500mV

= 1.1A

I

LOAD

= 0.1μF, C

C

SET

–25 25

0

TEMPERATURE (°C)

OUT(NOMINAL)

REFERENCE CURRENT NOISE SPECTRAL DENSITY (pA/ √Hz)

Noise Spectral Density

10k

1k

100

+ 2V

, f=120Hz

P-P

= 2.2μF

OUT

125

50

100

75

150

3080 G24

10

1

ERROR AMPLIFIER NOISE SPECTRAL DENSITY (nV/√Hz)

FREQUENCY (Hz)

10k 100k10010 1k

1k

100

10

1.0

0.1

3080 G25

3080f

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LT3080

Output Voltage Noise

V

OUT

100μV/DIV

3080 G26

V

OUT

R

SET

C

SET

C

OUT

I

LOAD

= 1V

TIME 1ms/DIV

= 100k
= O.1μF

= 10μF

= 1.1A

UUU

PI FU CTIO S

V

CONTROL

pin for the control circuitry of the device. The current fl ow
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
specifi cations).

IN (Pins 7, 8/Pins 7, 8/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 specifi cations).

(Pin 5/Pin 5/Pin 4/NA): This pin is the supply

(DD/MS8E/T/ST)

Error Amplifi er Gain and Phase

3080 G28

300

250

200

PHASE (DEGREES)

150

100

50

0

–50

–100

–150

–200

20

15

10

5

0

–5

GAIN (dB)

–10

–15

–20

–25

–30

FREQUENCY (Hz)

10k 100k10010 1k 1M

IL = 1.1A

= 100mA

I

L

IL = 1.1A

IL = 100mA

OUT (Pins 1-3/Pins 1-3/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 1): This pin is the input to the
error amplifi er and the regulation set point for the device.
A fi xed current of 10μA fl ows 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.

NC (Pin 6/Pin 6/Pin 1/NA): No Connection. No Connect
pins have no connection to internal circuitry and may be
tied to V

IN

, V

CONTROL

, V

, GND, or fl oated.

OUT

Exposed Pad (Pin 9/Pin 9/NA/NA): OUT on MS8E and
DFN packages.

TAB: OUT on TO-220 and SOT-223 packages.

3080f

7

LT3080

BLOCK DIAGRA

W

V

CONTROL

IN

10μA

+

–

3080 BD

OUTSET

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APPLICATIO S I FOR ATIO

The LT3080 regulator is easy to use and has all the pro­tection 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 con­nected to the non-inverting input of a power operational
amplifi er. The power operational amplifi er provides a low
impedance buffered output to the voltage on the non-invert­ing input. A single resistor from the non-inverting 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
defi ned by the input power supply.

What is not so obvious from this architecture are the ben­efi ts 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 fi xed at a percentage of the output
voltage but is a fi xed fraction of millivolts. Use of a true
current source allows all the gain in the buffer amplifi er
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 300mV, two
supplies can be used to power the LT3080 to reduce dis­sipation: a higher voltage supply for the control circuitry
and a lower voltage supply for the collector. This increases
effi ciency 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 300mV dropout
on the IN pin and minimizing the power dissipation. This
allows for a 1.1A supply regulating from 2.5V
or 1.8V

to 1.2V

IN

with low dissipation.

OUT

IN

to 1.8V

OUT

3080f

8

LT3080

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APPLICATIO S I FOR ATIO

SET

R

LT3080

SET

+
–

C

SET

OUT

3080 F01

V

OUT

C

OUT

IN

V

CONTROL

+

+

V

V

CONTROL

IN

Figure 1. Basic Adjustable Regulator

Output Voltage

The LT3080 generates a 10μA reference current that fl ows
out of the SET pin. Connecting a resistor from SET to
ground generates a voltage that becomes the reference
point for the error amplifi er (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., Tefl on, Kel-F); cleaning
of all insulating surfaces to remove fl uxes and other resi­dues 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 signifi cant 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 suffi cient.

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.

values of output capacitance decrease peak

Larger

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 capaci­tor 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

in Figure 1)

SET

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 specifi ed with EIA temperature char­acteristic 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 voltage
and temperature coeffi cients 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 avail-

3080f

9

LT3080

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APPLICATIO S I FOR ATIO

20

0

–20

–40

–60

CHANGE IN VALUE (%)

–80

–100

0

Figure 2. Ceramic Capacitor DC Bias Characteristics

40

20

0

BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF

X5R

Y5V

26

4

8

DC BIAS VOLTAGE (V)

14

12

10

X5R

16

3080 F02

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

–20

–40

–60

CHANGE IN VALUE (%)

–80

BOTH CAPACITORS ARE 16V,
1210 CASE SIZE, 10μF

–100

–50

–25 0

TEMPERATURE (°C)

Y5V

50 100 125

25 75

3080 F03

Figure 3. Ceramic Capacitor Temperature Characteristics

able 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 signifi cant enough
to drop capacitor values below appropriate levels. Capaci­tor DC bias characteristics tend to improve as component
case size increases, but expected capacitance at operating
voltage should be verifi ed.

Voltage and temperature coeffi cients 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

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 (5

V

4.8V TO 28V

V

IN

V

CONTROL

V

V

CONTROL

IN

IN

1μF

Figure 4. Parallel Devices

SET

SET

165k

LT3080

+
–

LT3080

+
–

OUT

OUT

10mΩ

10mΩ

3080 F04

10μF

V

OUT

3.3V
2A

3080f

10

LT3080

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APPLICATIO S I FOR ATIO

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 fi rst test was done with approximately 0.7V input­to-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 excel­lent. 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 tempera­ture from exceeding 125°C. A 3-meter-per-second airfl ow
across the devices will decrease the device temperature
about 20°C providing a margin for higher operating ambi­ent temperatures.

Both at low power and relatively high power levels de­vices 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 5. Temperature Rise at 700mW Dissipation

Figure 6. Temperature Rise at 1.7W Dissipation

3080f

11

LT3080

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APPLICATIO S I FOR ATIO

from the error amplifi er must be considered, and the gain
created by using a resistor divider cannot be forgotten.

Traditional low noise regulators bring the voltage refer­ence 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 (1nA
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 √⎯4⎯k⎯T⎯R (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 er­rors 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.

over the

RMS

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 fi rst 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 volt­age 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. Com­mon 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.

One problem that a normal linear regulator sees with refer­ence 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 fi gures do not increase
accordingly. Error amplifi er noise is typically 125nV/√
(40μV

over the 10Hz to 100kHz bandwidth); this is

RMS

⎯

Hz

another factor that is RMS summed in to give a fi nal noise
fi gure for the regulator.

Curves in the Typical Performance Characteristics show
noise spectral density and peak-to-peak noise character­istics for both the reference current and error amplifi er
over the 10Hz to 100kHz bandwidth.

Overload Recovery

Like many IC power regulators, the LT3080 has safe operat­ing area (SOA) protection. The SOA protection decreases

12

Load Regulation

Because the LT3080 is a fl oating 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

SET

LT3080

+
–

R

SET

RESISTANCE

OUT

PARASITIC

R

P

R

P

R

P

LOAD

3080 F07

3080f

IN

V

CONTROL

Figure 7. Connections for Best Load Regulation

LT3080

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APPLICATIO S I FOR ATIO

of the connections between the regulator and the load.
The data sheet specifi cation 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 regula­tion 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 cir­cuitry designed to protect it under overload conditions.
For continuous normal load conditions, maximum junc­tion 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 gener­ated by power devices.

Junction-to-case thermal resistance is specifi ed from the
IC junction to the bottom of the case directly below the
die. This is the lowest resistance path for heat fl ow. Proper
mounting is required to ensure the best possible thermal
fl ow 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 fi xed board size. All mea-

surements were taken in still air on two-sided 1/16” FR-4
board with one ounce copper.

Table 2. MSE Package, 8-Lead MSOP

COPPER AREA

TOPSIDE* BACKSIDE BOARD AREA

2500mm
1000mm

*Device is mounted on topside

Table 3. DD Package, 8-Lead DFN

TOPSIDE* BACKSIDE BOARD AREA

2500mm
1000mm

*Device is mounted on topside

Table 4. ST Package, 3-Lead SOT-223

TOPSIDE* BACKSIDE BOARD AREA

2500mm
1000mm

*Device is mounted on topside

2

2

2

225mm

2

100mm

COPPER AREA

2

2

2

225mm

2

100mm

COPPER AREA

2

2

2

225mm

2

100mm

2500mm22500mm
2500mm22500mm
2500mm22500mm
2500mm22500mm

2500mm22500mm
2500mm22500mm
2500mm22500mm
2500mm22500mm

2500mm22500mm
2500mm22500mm
2500mm22500mm
2500mm22500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

2

2

2

2

(JUNCTION-TO-AMBIENT)

2

2

2

2

(JUNCTION-TO-AMBIENT)

2

2

2

2

55°C/W
57°C/W
60°C/W
65°C/W

THERMAL RESISTANCE

60°C/W
62°C/W
65°C/W
68°C/W

THERMAL RESISTANCE

48°C/W
48°C/W
56°C/W
62°C/W

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 V

CONTROL

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

2

temperature be for the DFN package on a 2500mm

2

with topside copper area of 500mm

?

board

3080f

13

LT3080

A

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APPLICATIO S I FOR ATIO

The power in the drive circuit equals:

DRIVE

CONTROL

= (V

CONTROL

is equal to I

P
where I

of output current. A curve of I
in the Typical Performance Characteristics curves.

The power in the output transistor equals:
P

OUTPUT

= (VIN – V

The total power equals:

TOTAL

= P

DRIVE

P
The current delivered to the SET pin is negligible and can

be ignored.
V

CONTROL(MAX CONTINUOUS)

V

IN(MAX CONTINUOUS)

= 0.9V, I

V

OUT

OUT

Power dissipation under these conditions is equal to:
PDRIVE = (V

I

CONTROL

P

DRIVE

CONTROL

I

OUT

=

60

= (3.630V – 0.9V)(17mA) = 46mW

+ P

– V

OUT

OUTPUT

OUT

OUT

CONTROL

)(I

OUT

)(I

CONTROL

/60. I

)

CONTROL

= 3.630V (3.3V + 10%)

= 1.575V (1.5V + 5%)

= 1A, TA = 50°C

– V

1A

=

OUT

= 17mA

)(I

CONTROL

60

vs I

)

is a function

can be found

OUT

)

Junction Temperature will be equal to:

= TA + P

T

J

= 50°C + 721mW • 64°C/W = 96°C

T

J

• θJA (approximated using tables)

TOTAL

In this case, the junction temperature is below the maxi­mum rating, ensuring reliable operation.

Reducing Power Dissipation

In some applications it may be necessary to reduce
the power dissipation in the LT3080 package without
sacrifi cing output current capability. Two techniques are
available. The fi rst technique, illustrated in Figure 8, em­ploys a resistor in series with the regulator’s input. The
voltage drop across R

decreases the LT3080’s IN-to-OUT

S

differential voltage and correspondingly decreases the
LT3080’s power dissipation.

As an example, assume: VIN = V

and I

OUT(MAX)

= 1A. Use the formulas from the Calculating

CONTROL

= 5V, V

OUT

= 3.3V

Junction Temperature section previously discussed.
Without series resistor R

, power dissipation in the LT3080

S

equals:

1A



P

TOTAL

= 5V – 3.3V

()



•









60

+ 5V – 3.3V

()

•1

P

OUTPUT

P

OUTPUT

= (VIN – V
= (1.575V – 0.9V)(1A) = 675mW

OUT

)(I

OUT

)

Total Power Dissipation = 721mW

V

V

C1

Figure 8. Reducing Power Dissipation Using a Series Resistor

CONTROL

LT3080

SET

R

SET

IN

+
–

OUT

R

S

C2

3080 F08

VINʹ

V

IN

OUT

If the voltage differential (V
transistor is chosen as 0.5V, then R

RS=

= 1.73W

5V – 3.3V − 0.5V

1A

) across the NPN pass

DIFF

equals:

S

= 1.2Ω

Power dissipation in the LT3080 now equals:

1A



P

TOTAL

= 5V – 3.3V

()



•

+ 0.5V





()





60

•1A= 0.53W

The LT3080’s power dissipation is now only 30% compared
to no series resistor. R

dissipates 1.2W of power. Choose

S

appropriate wattage resistors to handle and dissipate the
power properly.

3080f

14

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APPLICATIO S I FOR ATIO

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
fl ow, reducing the current fl owing 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: V

5.5V, V
I

OUT(MIN)

than 90% of I
Calculating R

RP=

= 3.3V, V

OUT

OUT(MIN)

= 0.7A. Also, assuming that RP carries no more

OUT(MIN)

yields:

P

5.5V – 3.2V

= 3.65Ω

0.63A

= V

IN

= 3.2V, I

= 630mA.

(5% Standard value = 3.6Ω)

CONTROL

= 5V, V

OUT(MAX)

IN(MAX)

=

= 1A and

The maximum total power dissipation is (5.5V – 3.2V) •
1A = 2.3W. However the LT3080 supplies only:

5.5V – 3.2V

1A –

3.6Ω

= 0.36A

Therefore, the LT3080’s power dissipation is only:
P
R

= (5.5V – 3.2V) • 0.36A = 0.83W

DIS

dissipates 1.47W of power. As with the fi rst technique,

P

choose appropriate wattage resistors to handle and dis­sipate the power properly. With this confi guration, 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.

V

V

C1

Figure 9. Reducing Power Dissipation Using a Parallel Resistor

CONTROL

SET

R

SET

LT3080

+
–

IN

OUT

IN

R

P

V

OUT

C2

3080 F09

3080f

15

LT3080

TYPICAL APPLICATIO S

U

Higher Output Current

50Ω

V

MJ4502

CONTROL

IN

LT3080

V

IN

6V

+

SET

332k

+
–

OUT

4.7μF

V

OUT

3.3V
5A

+

100μF

3080 TA02

ON OFF

100μF

1μF

Adding Shutdown

V

IN

V

CONTROL

Q1
VN2222LL

SHUTDOWN

IN

LT3080

+
–

SET

R1

*

Q2 INSURES ZERO OUTPUT
IN THE ABSENCE OF ANY
OUTPUT LOAD.

3080 TA04

OUT

Q2*
VN2222LL

V

OUT

Current Source

V

10V

V

CONTROL

IN

IN

LT3080

+

1μF

SET

–

100k

OUT

1Ω

I

OUT

0A TO 1A

4.7μF

3080 TA03

16

Low Dropout Voltage LED Driver

V

C1

CONTROL

LT3080

D1

IN

+
–

SET

R1

24.9k

OUT

R2

2.49Ω

3080 TA05

V

100mA

IN

3080f

TYPICAL APPLICATIO S

LT3080

U

Using a Lower Value SET Resistor

V

IN

12V

4.8V to 28V

V

CONTROL

C1
1μF

V

IN

IN

LT3080

+

SET

R1

49.9k
1%

R
10k

–

SET

1mA

OUT

R2
499Ω
1%

3080 TA06

V

OUT

0.5V TO 10V

C

OUT

4.7μF

V

= 0.5V + 1mA • R

OUT

SET

Adding Soft-Start

SET

R1
332k

LT3080

+
–

OUT

3080 TA07

V

OUT

3.3V
1A

C

OUT

4.7μF

C1
1μF

V

CONTROL

D1
1N4148

C2

0.01μF

IN

V

7V TO 28V

Coincident Tracking

SET
169k

C3

4.7μF

LT3080

+
–

V

OUT2

3.3V

OUT

V

OUT3

5V

4.7μF

3080 TA08

3080f

IN

V

CONTROL

SET
R2

80.6k

C2

4.7μF

LT3080

+
–

V

OUT1

2.5V
1A

OUT

IN

V

CONTROL

LT3080

V

CONTROL

IN

IN

+

SET

R1
249k

–

OUT

C1

1.5μF

17

LT3080

TYPICAL APPLICATIO S

U

Lab Supply

V

12V TO 18V

SETSET

LT3080

+
–

R4
1MEG

OUTOUT

4.7μF 100μF

+

V

OUT

0V TO 10V

3080 TA09

IN

V

CONTROL

+

15μF

LT3080

+
–

1Ω

+

100k

0A TO 1A

V

CONTROL

15μF

ININ

High Voltage Regulator

SET

R

SET

2MEG

6.1V

LT3080

+
–

4.7μF

OUT

V

OUT

1A

3080 TA10

V

OUT

V

OUT

= 20V

= 10μA • R

SET

V

50V

10k

IN

1N4148

IN

BUZ11

V

CONTROL

+

10μF

+

15μF

18

Ramp Generator

SET

LT3080

+
–

1μF

OUT

V

4.7μF

3080 TA12

OUT

3080f

V

IN

5V

1μF

IN

V

CONTROL

VN2222LL VN2222LL

TYPICAL APPLICATIO S

LT3080

U

Reference Buffer

LT3080

V

CONTROL

IN

V

IN

+

LT1019

GND

INPUT

OUTPUT

–

SET

C1
1μF

OUT

*

V

OUT

C2

4.7μF

3080 TA11

*MIN LOAD 0.5mA

Ground Clamp

5k

LT3080

+
–

1N4148

OUT

20Ω

4.7μF

V

EXT

V

OUT

V

CONTROL

1μF

IN

V

IN

Boosting Fixed Output Regulators

5V

10μF

*4mV DROP ENSURES LT3080 IS
OFF WITH NO LOAD

MULTIPLE LT3080’S CAN BE USED

LT1963-3.3

SET

3080 TA13

LT3080

+
–

20mΩ

42Ω* 47μF

33k

OUT

20mΩ

3.3V

2.6A

3080 TA20

OUT

3080f

19

LT3080

TYPICAL APPLICATIO S

Low Voltage, High Current Adjustable High Effi ciency Regulator*

U

2.7V TO 5.5V

†

100μF

PV

IN

SV

+

2×

2.2MEG 100k

1000pF

IN

LTC3414

PGOOD
RUN/SS

SYNC/MODE

SGND PGND

*DIFFERENTIAL VOLTAGE ON LT3080
IS 0.6V SET BY THE V

†

MAXIMUM OUTPUT VOLTAGE IS 1.5V

BELOW INPUT VOLTAGE

0.47μH

SW

I

TH

12.1k

R

T

294k

V

FB

78.7k

124k

OF THE 2N3906 PNP.

BE

470pF

+

2×
100μF

2N3906

10k

V

CONTROL

V

CONTROL

V

CONTROL

IN

LT3080

+
–

SET

IN

LT3080

OUT

20mΩ

+
–

SET

IN

LT3080

OUT

20mΩ

0V TO 4V
4A

†

+
–

SET

OUT

20mΩ

20

V

CONTROL

IN

LT3080

+
–

SET

100k

3080 TA18

OUT

20mΩ

+

100μF

3080f

TYPICAL APPLICATIO S

CMDSH-4E

LT3080

U

Adjustable High Effi ciency Regulator*

4.5V TO 25V

†

10μF

1μF

V

BOOST

IN

100k

0.1μF

*DIFFERENTIAL VOLTAGE ON LT3080
≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD.

†

BELOW INPUT VOLTAGE

LT3493

GND

SW

FB

10k

IN

SHDN

MAXIMUM OUTPUT VOLTAGE IS 2V

0.1μF
10μH

MBRM140

68μF

TP0610L

2 Terminal Current Source

C

*

COMP

LT3080

V

CONTROL

10k

IN

LT3080

+

SET

1MEG

–

3080 TA19

OUT

4.7μF

0V TO 10V
1A

†

V

CONTROL

*C

COMP

R1 ≤ 10Ω 10μF
R1 ≥ 10Ω 2.2μF

SET

+
–

100k

R1

3080 TA21

I

OUT

1V

=

R1

3080f

21

LT3080

PACKAGE DESCRIPTIO

U

DD Package

8-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1698)

0.675 ±0.05

R = 0.115

TYP

0.38 ± 0.10

85

3.5 ±0.05

5.23

(.206)

MIN

0.42 ± 0.038

(.0165 ± .0015)

TYP

RECOMMENDED SOLDER PAD LAYOUT

1.65 ±0.05
(2 SIDES)2.15 ±0.05

0.25 ± 0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

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

BOTTOM VIEW OF

EXPOSED PAD OPTION

1

8

2.794 ± 0.102
(.110 ± .004)

2.38 ±0.05
(2 SIDES)

2.06 ± 0.102

(.081 ± .004)

1.83 ± 0.102
(.072 ± .004)

2.083 ± 0.102

(.082 ± .004)

0.65

(.0256)

BSC

0.50
BSC

0.889 ± 0.127
(.035 ± .005)

(.126 – .136)

3.20 – 3.45

1.65 ± 0.10

0.00 – 0.05

(2 SIDES)

0.25 ± 0.05

BOTTOM VIEW—EXPOSED PAD

PACKAGE
OUTLINE

PIN 1

TOP MARK

(NOTE 6)

0.200 REF

3.00 ±0.10
(4 SIDES)

0.75 ±0.05

MS8E Package

8-Lead Plastic MSOP

(Reference LTC DWG # 05-08-1662)

3.00 ± 0.102
(.118 ± .004)

(NOTE 3)

PLANE

4.90 ± 0.152

(.193 ± .006)

0.22 – 0.38

(.009 – .015)

TYP

1.10

(.043)

MAX

0.65

(.0256)

BSC

0.254

(.010)

GAUGE PLANE

0.18

(.007)

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

DETAIL “A”

0° – 6° TYP

0.53 ± 0.152

(.021 ± .006)

DETAIL “A”

SEATING

2.38 ±0.10
(2 SIDES)

8

7

12

6

3

5

4

(DD8) DFN 1203

14

0.50 BSC

0.52

(.0205)

REF

3.00 ± 0.102

(.118 ± .004)

(NOTE 4)

0.86

(.034)

REF

0.127 ± 0.076
(.005 ± .003)

MSOP (MS8E) 0603

22

3080f

PACKAGE DESCRIPTIO

.390 – .415

(9.906 – 10.541)

.460 – .500

(11.684 – 12.700)

U

.147 – .155

(3.734 – 3.937)

.230 – .270

(5.842 – 6.858)

(14.478 – 15.748)

.330 – .370

(8.382 – 9.398)

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

DIA

.570 – .620

.700 – .728

(17.78 – 18.491)

.165 – .180

(4.191 – 4.572)

.620

(15.75)

TYP

LT3080

.045 – .055

(1.143 – 1.397)

BSC

.264 – .287

(6.70 – 7.30)

.067

(1.70)

.130 – .146

(3.30 – 3.71)

.0905

(2.30)

BSC

.028 – .038

(0.711 – 0.965)

.248 – .264

(6.30 – 6.71)

.114 – .124

(2.90 – 3.15)

SEATING PLANE

.152 – .202

.260 – .320

(6.60 – 8.13)

(3.861 – 5.131)

ST Package

3-Lead Plastic SOT-223

(Reference LTC DWG # 05-08-1630)

.059 MAX

.033 – .041

(0.84 – 1.04)

.135 – .165

(3.429 – 4.191)

.129 MAX

.059 MAX

.181 MAX

RECOMMENDED SOLDER PAD LAYOUT

* MEASURED AT THE SEAT

.039 MAX

.095 – .115

(2.413 – 2.921)

.155 – .195*

(3.937 – 4.953)

.013 – .023

(0.330 – 0.584)

.248 BSC

.090
BSC

.071

(1.80)

MAX

10° – 16°

10°

MAX

.024 – .033

(0.60 – 0.84)

.181

(4.60)

BSC

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 representa­tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

.012

(0.31)

MIN

.0008 – .0040

(0.0203 – 0.1016)

.010 – .014

(0.25 – 0.36)

10° – 16°

ST3 (SOT-233) 0502

3080f

23

LT3080

TYPICAL APPLICATIO

U

Paralleling Regulators

LT3080

V

CONTROL

IN

+

V

4.8V TO 28V

–

SET

LT3080

V

CONTROL

IN

IN

OUT

20mΩ

+
–

1μF

SET

165k

OUT

20mΩ

10μF

3080 TA14

V

OUT

3.3V
2A

RELATED PARTS

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: 40μV

TO-220, DD, SOT-223 and SO-8 Packages

LT1965 1.1A Low Noise LDO 290mV Dropout Voltage, Low Noise 40μV

V

= 1.2V to 19.5V, Stable with Ceramic Caps TO-220, DDPak, MSOP

OUT

and 3mm × 3mm DFN packages.

LT C®3026 1.5A Low Input Voltage VLDOTM Regulator VIN: 1.14V to 3.5V (Boost Enabled), 1.14V to 5.5V (with External 5V),

V

= 0.1V, IQ = 950μA, Stable with 10μF Ceramic Capacitors, 10-Lead

DO

MSOP and DFN Packages

Switching Regulators

LT1976 High Voltage, 1.5A Step-Down Switching Regulator f = 200kHz, I
LTC3414 4A (I

), 4MHz Synchronous Step-Down DC/DC

OUT

95% Effi ciency, VIN: 2.25V to 5.5V, V

= 100μA, TSSOP-16E Package

Q

OUT(MIN)

Converter

LTC3406/LTC3406B 600mA (I

Converter

LTC3411 1.25A (I

Converter

), 1.5MHz Synchronous Step-Down DC/DC

OUT

), 4MHz Synchronous Step-Down DC/DC

OUT

95% Effi ciency, VIN: 2.5V to 5.5V, V
I

< 1μA, ThinSOTTM Package

SD

95% Effi ciency, VIN: 2.5V to 5.5V, V
I

< 1μA, 10-Lead MS or DFN Packages

SD

OUT(MIN)

OUT(MIN)

VLDO and ThinSOT are trademarks of Linear Technology Corporation.

, VIN = 2.5V to 20V,

RMS

, VIN = 1.8V to 20V,

RMS

= 0.8V, TSSOP Package

= 0.6V, IQ = 20μA,

= 0.8V, IQ = 60μA,

24

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

3080f

LT 1107 • PRINTED IN USA

© LINEAR TECHNOLOGY CORPORATION 2007