LT3080IDD-1 - ANALOG DEVICES

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

–

LT3080-1

VIN

4.8V TO 28V VCONTROL

OUT*

25mΩ

10µF

VOUT

3.3V

2.2A

*OUTPUTS CAN BE

DIRECTLY MOUNTED

TO POWER PLANE

30801 TA01

165k

SET

1µF

–

LT3080-1

VCONTROL

OUT*

25mΩ

SET

Typical applicaTion

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

applicaTions

n Internal Ballast Resistor Permits Direct

Connection to Power Plane 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

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 and 3mm × 3mm DFN

FeaTures DescripTion

Parallelable 1.1A

Adjustable Single Resistor

Low Dropout Regulator

The LT

3080-1 is a 1.1A low dropout linear regulator that

incorporates an internal ballast resistor to allow direct

paralleling of devices without the need for PC board trace

resistors. The internal ballast resistor allows multiple de-

vices to be paralleled directly on a surface mount board

for higher output current and power dissipation while

keeping board layout simple and easy. The device brings

out the collector of the pass transistor to allow low dropout

operation—down to 350mV—when used with multiple

input supplies.

The LT3080-1 is capable of supplying a wide output volt-

age range. A reference current through a single resistor

programs the output voltage to any level between zero

and 36V. The LT3080-1 is stable with 2.2µF of ceramic

capacitance on the output, not requiring additional ESR

as is common with other regulators.

Internal protection includes current limiting and thermal

limiting. The LT3080-1 regulator is offered in the 8-lead

MSOP (with an Exposed Pad for better thermal charac-

teristics) and 3mm × 3mm DFN packages.

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.

Paralleling Regulators Offset Voltage Distribution

VOS DISTRIBUTION (mV)

30801 TA01b

–1 01

–2

N = 13250

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

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

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 Package Only ..........................................300°C

orDer inFormaTion

pin conFiguraTion

absoluTe maximum raTings

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

LT3080EDD-1#PBF LT3080EDD-1#TRPBF LDPM 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C

LT3080IDD-1#PBF LT3080IDD-1#TRPBF LDPM 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C

LT3080EMS8E-1#PBF LT3080EMS8E-1#TRPBF LTDPN 8-Lead Plastic MSOP –40°C to 125°C

LT3080IMS8E-1#PBF LT3080IMS8E-1#TRPBF LTDPN 8-Lead Plastic MSOP –40°C to 125°C

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

LT3080EDD-1 LT3080EDD-1#TR LDPM 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C

LT3080IDD-1 LT3080IDD-1#TR LDPM 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C

LT3080EMS8E-1 LT3080EMS8E-1#TR LTDPN 8-Lead Plastic MSOP –40°C to 125°C

LT3080IMS8E-1 LT3080IMS8E-1#TR LTDPN 8-Lead Plastic MSOP –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/

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

The l denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C.

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

–2

–3.5

3.5

Load Regulation ∆ISET

∆VOS

∆ILOAD = 1mA to 1.1A

∆ILOAD = 1mA to 1.1A (Note 8)

–0.1

27.5

Line Regulation (Note 9) ∆ISET

∆VOS

VIN = 1V to 22V, VCONTROL=1V to 22V, ILOAD=1mA

l 0.1

0.003

0.5 nA/V

mV/V

Minimum Load Current (Notes 3, 9) VIN = VCONTROL = 10V

VIN = VCONTROL = 22V

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

CONTROL Pin Current (Note 5) ILOAD = 100mA

ILOAD = 1.1A

Current Limit (Note 9) 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

, ILOAD = 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 LT3080-1 is tested and specified under pulse load conditions such

that TJ ≅ TA. The LT3080E-1 is tested at TA = 25°C. Performance of the

LT3080E-1 over the full –40°C and 125°C operating temperature range

is assured by design, characterization, and correlation with statistical

process controls. The LT3080I-1 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 LT3080-1, 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 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

resistor shot noise and reference current noise; output noise is then equal

to error amplifier noise (see the 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 22V. 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 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 specified maximum operating junction temperature may impair device

reliability.

elecTrical characTerisTics

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

INPUT-TO-OUTPUT VOLTAGE (V)

OFFSET VOLTAGE (mV)

–0.25

0.25

18 30

30801 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

Set Pin Current

Set Pin Current Distribution

Offset Voltage (VOUT – VSET)

Offset Voltage

Dropout Voltage

(Minimum IN Voltage)

TEMPERATURE (°C)

–50

SET PIN CURRENT (µA)

10.00

10.10

150

30801 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

30801 G02

9.90 10.00 10.10

9.80

N = 13792

TEMPERATURE (°C)

–50

OFFSET VOLTAGE (mV)

1.0

150

30801 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)

30801 G04

–1 01

–2

N = 13250

TEMPERATURE (°C)

–50

MINIMUM LOAD CURRENT (mA)

0.4

0.6

150

30801 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

30801 G09

100

00.2 0.4 0.8

300

350

400

1.2

TJ = 25°C

TJ = 125°C

Offset Voltage

Offset Voltage Distribution

Minimum Load Current

Load Regulation

Typical perFormance characTerisTics

LOAD CURRENT (A)

OFFSET VOLTAGE (mV)

–30

–25

–20

0.6 1.0

30801 G06

–35

–40

–45 0.2 0.4 0.8

–10

–15

–5

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)

–20

–10

150

30801 G07

–30

–50 050 100

–25 25 75 125

–25

–15

–35

–40

–45

–5

–20

–10

∆ILOAD = 1mA TO 1.1A

VIN – VOUT = 2V

CHANGE IN REFERENCE CURRENT

CHANGE IN OFFSET VOLTAGE

(VOUT – VSET)

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

TIME (µs)

OUTPUT VOLTAGE (V) INPUT VOLTAGE (V)

30801 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

Dropout Voltage

(Minimum IN Voltage)

Dropout Voltage

(Minimum VCONTROL Pin Voltage)

Dropout Voltage

(Minimum VCONTROL Pin Voltage)

Current Limit Load Transient Response

Load Transient Response Line Transient Response

TEMPERATURE (°C)

–50

MINIMUM IN VOLTAGE (VIN – VOUT) (mV)

200

300

150

30801 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

30801 G11

0.4

0.2

00.2 0.4 0.8

1.2

1.4

1.6

1.2

TJ = 125°C

TJ = 25°C

TJ = –50°C

TEMPERATURE (°C)

–50

MINIMUM CONTROL VOLTAGE (VCONTROL – VOUT) (V)

0.8

1.2

150

30801 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

TIME (µs)

IN/CONTROL

VOLTAGE (V)

OUTPUT VOLTAGE

DEVIATION (mV)

–25

30801 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

TEMPERATURE (°C)

–50

CURRENT LIMIT (A)

0.8

1.2

150

30801 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

30801 G14

0.4

0.2

06 12 24

1.2

1.4

1.6

36*

TJ = 25°C

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

Typical perFormance characTerisTics

TIME (µs)

OUTPUT VOLTAGE

DEVIATION (mV)LOAD CURRENT (mA)

–20

30801 G15

400

200

–40

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

TIME (µs)

OUTPUT VOLTAGE

DEVIATION (mV)

LOAD CURRENT (A)

–50

150

30801 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

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

FREQUENCY (Hz)

ERROR AMPLIFIER NOISE

SPECTRAL DENSITY (nV/√Hz)

REFERENCE CURRENT NOISE

SPECTRAL DENSITY (pA/ √Hz)

10k

10k 100k10010 1k

30801 G26

100

0.1

1.0

100

VCONTROL Pin Current

Residual Output Voltage with

Less Than Minimum Load

Ripple Rejection - Single Supply

Ripple Rejection - Dual Supply -

IN Pin

Ripple Rejection (120Hz) Noise Spectral Density

Ripple Rejection - Dual Supply -

VCONTROL Pin

LOAD CURRENT (A)

CONTROL PIN CURRENT (mA)

0.2 0.4 0.6 0.8

30801 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

30801 G21

2k1k

VIN = 20V

VIN = 5V

VIN = 10V

SET PIN = 0V

VIN VOUT

RTEST

FREQUENCY (Hz)

RIPPLE REJECTION (dB)

100

10k 100k10010 1k 1M

30801 G22

VIN = 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

30801 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

30801 G24

VIN = VOUT (NOMINAL) + 1V

VCONTROL = VOUT (NOMINAL) +2V

RIPPLE = 50mVP–P

COUT = 2.2µF CERAMIC

ILOAD = 1.1A

VCONTROL Pin Current

INPUT-TO-OUTPUT DIFFERENTIAL (V)

CONTROL PIN CURRENT (mA)

612 18 24

30801 G19

30 36*

ILOAD = 1.1A

ILOAD = 1mA

DEVICE IN

CURRENT LIMIT

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

TEMPERATURE (°C)

–50

RIPPLE REJECTION (dB)

050 75

30801 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

Typical perFormance characTerisTics

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Output Voltage Noise Error Amplifier Gain and Phase

FREQUENCY (Hz)

–30

GAIN (dB)

PHASE (DEGREES)

–10

10k 100k10010 1k 1M

30801 G28

–20

–15

–25

–5

–200

300

–100

100

200

–50

250

–150

150

IL = 1.1A

IL = 100mA

IL = 1.1A

VCONTROL (Pin 5/Pin 5): This pin is the supply pin for the

control circuitry of the device. The current 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 specifica-

tions).

IN (Pins 7, 8/Pins 7, 8): This is the collector to the power

device of the LT3080-1. 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): No Connection. No Connect 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): 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): This pin is the input to the error am-

plifier 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): OUT on MS8E and DFN

packages.

(DD/MS8E)

VOUT

100µV/DIV

TIME 1ms/DIV 30801 G27

VOUT = 1V

RSET = 100k

CSET = O.1µF

COUT = 10µF

ILOAD = 1.1A

Typical perFormance characTerisTics

pin FuncTions

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

applicaTions inFormaTion

The LT3080-1 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 LT3080-1 is especially well suited to applications

needing multiple rails. The new architecture adjusts down

to zero with a single resistor handling modern low volt-

age 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 non-inverting input of a power operational

amplifier. The power operational amplifier 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 maxi-

mum 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 LT3080-1, 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 LT3080-1 also incorporates an internal ballast resistor

to allow for direct paralleling of devices without the need for

PC board trace resistors or sense resistors. This internal

ballast resistor allows multiple devices to be paralleled

directly on a surface mount board for higher output current

and higher power dissipation while keeping board layout

simple and easy. It is not difficult to add more regulators

for higher output current; inputs of devices are all tied

together, outputs of all devices are tied directly together,

and SET pins of all devices are tied directly together. Be-

cause of the internal ballast resistor, devices automatically

share the load and the power dissipation.

The LT3080-1 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 LT3080-1 to reduce

dissipation: a higher voltage supply for the control circuitry

–

VCONTROL

10µA

25mΩ

30801 BD

OUTSET

block Diagram

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

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 LT3080-1 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 2.5VIN to 1.8VOUT

or 1.8VIN to 1.2VOUT with low dissipation.

Output Voltage

The LT3080-1 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 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 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 ca-

pacitance from SET to ground, 10pF to 20pF is sufficient.

Stability and Output Capacitance

The LT3080-1 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 LT3080-1, 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 (RSET 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

Figure 1. Basic Adjustable Regulator

–

LT3080-1

VCONTROL

OUT

30801 F01

SET

COUT

RSET

VOUT

CSET

VIN

25mΩ

applicaTions inFormaTion

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

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 voltage

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 tempera-

ture 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-

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 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

LT3080-1’s may be directly 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; the internal ballast

resistor equalizes the currents.

The worst-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

internal ballast resistors, which at full output current gives

better than 90 percent equalized sharing of the current.

The internal resistance of 25 milliohms (per device) only

adds about 25 millivolts of output regulation drop at an

DC BIAS VOLTAGE (V)

CHANGE IN VALUE (%)

30801 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 Figure 4. Parallel Devices

applicaTions inFormaTion

–

LT3080-1

VIN

VCONTROL

OUT

SET

25mΩ

–

LT3080-1

VIN

4.8V TO 28V

VOUT

3.3V

2.2A

VCONTROL

OUT

10µF

1µF

SET

165k

30801 F04

25mΩ

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

output of 2A. At low output voltage, 1V, this adds 2.5%

regulation. The output can be set 19mV high for lower ab-

solute error ±1.3%. Of course, more than two LT3080-1’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 LT3080-1 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

excellent. The thermograph in Figure 5 shows the tem-

perature 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 de-

vice. 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 tem-

perature 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 am-

bients, the temperature must be controlled to prevent

device temperature from exceeding 125°C. A three meter

per second airflow 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 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.

Figure 6. Temperature Rise at 1.7W Dissipation

Figure 5. Temperature Rise at 700mW Dissipation

applicaTions inFormaTion

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Quieting the Noise

The LT3080-1 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

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 LT3080-1 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 set-

ting resistor may be bypassed with a capacitor, though

this causes start-up time to increase as a factor of the RC

time constant.

The LT3080-1 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

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 LT3080-1, the unity-gain follower presents no gain

whatsoever from the SET pin to the output, so noise fig-

ures 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 LT3080-1 has safe oper-

ating 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 LT3080-1 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 section.

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 LT3080-1.

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.

applicaTions inFormaTion

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

As output current decreases below the midpoint, output

voltage increases above the nominal set-point. Correspond-

ingly, as output current increases above the midpoint,

output voltage decreases below the nominal set-point.

During a large output load transient, output voltage

perturbation is contained within a window that is tighter

than what would result if active voltage positioning is not

employed. Choose the SET pin resistor value by using the

formula below:

RSET =

OUT +

MID

•R

BALLAST

)

SET

where

IMID = 1/2 (IOUT(MIN) + IOUT(MAX))

RBALLAST = 25mΩ

ISET = 10µA

Thermal Considerations

The LT3080-1 has internal power and thermal limiting

circuitry 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. Note that the Exposed Pad is electrically

connected to the output.

Figure 7. Connections for Best Load Regulation

–

LT3080-1

VCONTROL

OUT

30801 F07

SET RSET

25mΩ

PARASITIC

RESISTANCE

LOAD

Load Regulation

Because the LT3080-1 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 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

regulation will be the sum of the LT3080-1 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.

applicaTions inFormaTion

The internal 25mΩ ballast resistor is outside of the

LT3080-1’s feedback loop. Therefore, the voltage drop

across the ballast resistor appears as additional DC load

regulation. However, this additional load regulation can

actually improve transient response performance by de-

creasing peak-to-peak output voltage deviation and even

save on total output capacitance. This technique is called

active voltage positioning and is especially useful for ap-

plications that must withstand large output load current

transients. For more information, see Design Note 224,

“Active Voltage Positioning Reduces Output Capacitors.”

The basic principle uses the fact that output voltage is

a function of output load current. Output voltage is set

based on the midpoint of the output load current range:

•IOUT(MIN) +IOUT(MAX)

( )

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

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.

Table 1. 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 2. 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

PCB layers, copper weight, board layout and thermal vias

affect the resultant thermal resistance. Although Tables 1

and 2 provide thermal resistance numbers for a 2-layer

board with 1 ounce copper, modern multilayer PCBs pro-

vide better performance than found in these tables. For

example, a 4-layer, 1 ounce copper PCB board with five

thermal vias from the DFN or MSOP exposed backside pad

to inner layers (connected to VOUT) achieves 40°C/W ther-

mal resistance. Demo circuit 995A’s board layout achieves

this 40°C/W performance. This is approximately a 33%

improvement over the numbers shown in Tables 1 and 2.

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?

The power in the drive circuit equals:

PDRIVE = (VCONTROL – VOUT)(ICONTROL)

where ICONTROL is equal to IOUT/60. ICONTROL is a func-

tion 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 =

OUT

=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.

applicaTions inFormaTion

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Figure 8. Reducing Power Dissipation Using a Series Resistor

–

LT3080-1 IN

VCONTROL

OUT VOUT

VIN′

VIN

30801 F08

SET

RSET

25mΩ

applicaTions inFormaTion

The second technique for reducing power dissipation,

shown in Figure 9, uses a resistor in parallel with the

LT3080-1. This resistor provides a parallel path for current

flow, reducing the current flowing through the LT3080-1.

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.

Reducing Power Dissipation

In some applications it may be necessary to reduce

the power dissipation in the LT3080-1 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 LT3080-1’s IN-to-

OUT differential voltage and correspondingly decreases

the LT3080-1’s power dissipation.

As an example, assume: VIN = VCONTROL = 5V, VOUT = 3.3V

and IOUT(MAX) = 1A. Use the formulas from the Calculat-

ing Junction Temperature section previously discussed.

Without series resistor RS, power dissipation in the

LT3080-1 equals:

PTOTAL =5V – 3.3V

( )

•1A

⎛

⎝

⎜⎞

⎠

⎟+5V – 3.3V

( )

•1A =1.73

If the voltage differential (VDIFF) across the NPN pass

transistor is chosen as 0.5V, then RS equals:

RS=

5V – 3.3V

−

0.5V

=1.2Ω

Power dissipation in the LT3080-1 now equals:

PTOTAL =5V – 3.3V

( )

•

⎛

⎝

⎜⎞

⎠

⎟+0.5V

( )

•1A =0.53

The LT3080-1’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 9. Reducing Power Dissipation Using a Parallel Resistor

–

VCONTROL

OUT VOUT

30801 F09

SET

RSET

LT3080-1

25mΩ

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 LT3080-1 supplies only:

1A –

5.5V – 3.2V

3.6Ω

=0.36A

Therefore, the LT3080-1’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

LT3080-1 supplies only 0.36A. Therefore, load current can

increase by 0.64A to 1.64A while keeping the LT3080-1

in its normal operating range.

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Adding Shutdown

Current Source

Typical applicaTions

–

LT3080-1

VIN

VCONTROL

OUT VOUT

30801 TA02

SET

ON OFF

SHUTDOWN

VN2222LL

Q2*

VN2222LL

*Q2 INSURES ZERO OUTPUT IN THE

ABSENCE OF ANY OUTPUT LOAD

25mΩ

1N4148

–

LT3080-1

VCONTROL

OUT

SET

25mΩ

LT3080-1

25mΩ

–

VCONTROL

OUT 1Ω

100k

30801 TA03

SET

IOUT

0A TO 2A

10µF

VIN

10V

–

LT3080-1

VCONTROL

OUT

SET

25mΩ

2.2µF

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Using a Lower Value SET Resistor

Adding Soft-Start

Typical applicaTions

2mA

VOUT

0.5V TO 10V

30801 TA04

SET

24.9k

RSET

4.99k

VOUT = 0.5V + 2mA • RSET

VIN

10V

–

LT3080-1

VCONTROL

OUT

SET

25mΩ

–

LT3080-1

VCONTROL

OUT

25mΩ

2.2µF

249Ω

COUT

10µF

30801 TA05

SET

165k

VIN

4.8V TO 28V

–

LT3080-1

VCONTROL

OUT

SET

25mΩ

–

LT3080-1

VCONTROL

OUT

25mΩ

2.2µF

COUT

10µF

VOUT

3.3V

2.2A

IN4148

0.01µF

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Typical applicaTions

Lab Supply

3080 TA06

SET

VIN

13V TO 18V

–

LT3080-1

VCONTROL

OUT

SET

25mΩ

0.5Ω

–

LT3080-1

VCONTROL

OUT

25mΩ

15µF 10µF

50k

0A TO 2A

CURRENT

LIMIT

+15µF 100µF

VOUT

0V TO 10V

SET

–

LT3080-1

VCONTROL

OUT

SET

25mΩ

–

LT3080-1

VCONTROL

OUT

25mΩ

500k

30801 TA07

20mΩ

42Ω* 47µF

3.3VOUT

2.6A

33k

*4mV DROP ENSURES LT3080-1 IS OFF WITH NO-LOAD

MULTIPLE LT3080-1’S CAN BE USED IN PARALLEL

–

10µF

OUT

SET

LT1963-3.3

LT3080-1

25mΩ

Boosting Fixed Output Regulators

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Low Voltage, High Current Adjustable High Efficiency Regulator*

LT3080-1

25mΩ

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

–

VCONTROL

OUT

SET

–

VCONTROL

OUT 0V TO

4V†

SET

–

VCONTROL

OUT

SET

30801 TA08

–

VCONTROL

OUT

100µF

SET

* DIFFERENTIAL VOLTAGE ON LT3080-1

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

† MAXIMUM OUTPUT VOLTAGE IS 1.5V

BELOW INPUT VOLTAGE

LT3080-1

25mΩ

LT3080-1

25mΩ

LT3080-1

25mΩ

Typical applicaTions

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

Adjustable High Efficiency Regulator*

2 Terminal Current Source

Typical applicaTions

30801 TA09

4.5V TO

25V†

10µF

68µF

0.1µF

10µH

MBRM140

10k

1µF

VIN BOOST

SHDN

GND

LT3493

CMDSH-4E

0.1µF

TP0610L +

–

VCONTROL

OUT

SET 4.7µF

TO 10V †

*DIFFERENTIAL VOLTAGE ON LT3080-1

≈ 1.4V SET BY THE TPO610L P-CHANNEL THRESHOLD.

1MEG

†MAXIMUM OUTPUT VOLTAGE IS 2V

BELOW INPUT VOLTAGE

LT3080-1

25mΩ

100k

30801 TA10

OUT

100k

CURRENT SET

–

CCOMP*

VCONTROL

SET

*CCOMP

R1 ≤ 10Ω 10µF

R1 ≥ 10Ω 2.2µF IOUT = 1V

LT3080-1

25mΩ

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

DD Package

8-Lead Plastic DFN (3mm × 3mm)

(Reference LTC DWG # 05-08-1698 Rev C)

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

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

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

MS8E Package

8-Lead Plastic MSOP, Exposed Die Pad

(Reference LTC DWG # 05-08-1662 Rev K)

package DescripTion

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

MSOP (MS8E) 0213 REV K

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 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)

5.10

(.201)

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

0.65

(.0256)

BSC

0.42 ±0.038

(.0165 ±.0015)

TYP

0.1016 ±0.0508

(.004 ±.002)

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 K)

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

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 9/11 Updated the Absolute Maximum Ratings, Order Information, and Note 2 in the Electrical Characteristics sections to

include I-grade parts.

2, 3

C 5/15 Added diode to shutdown application circuit. 16

(Revision history begins at Rev B)

LT3080-1

30801fc

For more information www.linear.com/LT3080-1

 LINEAR TECHNOLOGY CORPORATION 2008

LT 0515 REV C • PRINTED IN USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LT3080-1

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 Okay 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, 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, DDPak, 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

LT3080 1.1A, Parallelable, Low Noise,

Low Dropout Linear Regulator

300mV Dropout Voltage (2-Supply Operation), Low Noise: 40µVRMS, VIN : 1.2V to

36V, VOUT: 0V to 35.7V, Current-Based Reference with 1-Resistor VOUT Set, Directly

Parallelable (No Op Amp Required), Stable with Ceramic Capacitors, TO-220, SOT-223,

MSOP and 3mm × 3mm DFN Packages.

Switching Regulators

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

–

LT3080-1

VIN

4.8V TO 28V

VCONTROL

OUT

25mΩ

10µF

VOUT

3.3V

2.2A

30801 TA11

165k

SET

1µF

–

LT3080-1

VCONTROL

OUT

25mΩ

SET

Typical applicaTion

relaTeD parTs