LT3080EMS8E#PBF_技术文档

LT3080

Adjustable1.1A Single

Resistor Low Dropout

Regulator

FeaTures

DescripTion

TheLT^®3080isa1.1Alowdropoutlinearregulatorthatcan

be paralleled to increase output current or spread heat in

surface mounted boards. Architected as a precision cur-

rent source and voltage follower allows this new regulator

to be used in many applications requiring high current,

adjustability to zero, and no heat sink. Also the device

brings out the collector of the pass transistor to allow low

dropout operation —down to 350 millivolts— when used

with multiple supplies.

n

Outputs May be Paralleled for Higher Current and

Heat Spreading

n

Output Current: 1.1A

n

Single Resistor Programs Output Voltage

1% Initial Accuracy of SET Pin Current

Output Adjustable to 0V

Low Output Noise: 40µV

n

(10Hz to 100kHz)

RMS

n

Wide Input Voltage Range: 1.2V to 36V

Low Dropout Voltage: 350mV (Except SOT-223

Package)

A key feature of the LT3080 is the capability to supply a

wide output voltage range. By using a reference current

throughasingleresistor,theoutputvoltageisprogrammed

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.

n

<1mV Load Regulation

<0.001%/V Line Regulation

Minimum Load Current: 0.5mA

Stable with 2.2µF Minimum Ceramic Output Capacitor

Current Limit with Foldback and Overtemperature

Protected

n

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

5-Lead DD-Pak, TO-220 and 3-Lead SOT-223

Internal protection circuitry includes current limiting and

thermal limiting. The LT3080 regulator is offered in the

8-lead MSOP (with an exposed pad for better thermal

characteristics), a 3mm × 3mm DFN, 5-lead DD-Pak,

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

applicaTions

n

High Current All Surface Mount Supply

n

High Efﬁciency Linear Regulator

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.

n

Post Regulator for Switching Supplies

n

Low Parts Count Variable Voltage Supply

n

Low Output Voltage Power Supplies

Set Pin Current Distribution

Typical applicaTion

Variable Output Voltage 1.1A Supply

N = 13792

IN

LT3080

V

IN

1.2V TO 36V

V

CONTROL

+

–

1µF

OUT

V

OUT

SET

2.2µF

R

SET

V

= R

SET

• 10µA

OUT

10.00

SET PIN CURRENT DISTRIBUTION (µA)

9.80

9.90

10.10

10.20

3080 TA01a

3080 G02

3080fc

1

LT3080

absoluTe MaxiMuM raTings ^{(Note 1)(All Voltages Relative to V}_OUT

)

V

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

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)

CONTROL

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

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

pin conFiguraTion

TOP VIEW

FRONT VIEW

TOP VIEW

5

4

3

2

1

IN

OUT

SET

1

2

3

4

8

7

6

5

IN

NC

V

OUT

SET

1

2

3

4

8 IN

7 IN

6 NC

5 V

V

CONTROL

9

OUT

9

OUT

TAB IS

OUT

SET

NC

CONTROL

MS8E PACKAGE

8-LEAD PLASTIC MSOP

Q PACKAGE

DD PACKAGE

T

= 125°C, θ = 60°C/W, θ = 10°C/W

JA JC

JMAX

5-LEAD PLASTIC DD-PAK

8-LEAD (3mm × 3mm) PLASTIC DFN

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

T

= 125°C, θ = 64°C/W, θ = 3°C/W

T

= 125°C, θ = 30°C/W, θ = 3°C/W

JMAX

JA

JC

JMAX

JA

JC

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

FRONT VIEW

5

3

2

1

IN*

IN

TAB IS

OUT

4

V

CONTROL

OUT

SET

TAB IS

OUT

3

OUT

SET

NC

2

1

ST PACKAGE

3-LEAD PLASTIC SOT-223

*IN IS V AND IN TIED TOGETHER

T PACKAGE

5-LEAD PLASTIC TO-220

CONTROL

= 125°C, θ = 55°C/W, θ = 15°C/W

T

= 125°C, θ = 40°C/W, θ = 3°C/W

JA JC

JMAX

T

JMAX

JA

JC

3080fc

2

LT3080

orDer inForMaTion

LEAD FREE FINISH

LT3080EDD#PBF

LT3080IDD#PBF

LT3080EMS8E#PBF

LT3080IMS8E#PBF

LT3080EQ#PBF

LT3080IQ#PBF

TAPE AND REEL

PART MARKING*

LCBN

PACKAGE DESCRIPTION

8-Lead (3mm x 3mm) Plastic DFN

8-Lead Plastic MSOP

TEMPERATURE RANGE

LT3080EDD#TRPBF

LT3080IDD#TRPBF

LT3080EMS8E#TRPBF

LT3080IMS8E#TRPBF

LT3080EQ#TRPBF

LT3080IQ#TRPBF

LT3080ET#TRPBF

LT3080IT#TRPBF

LT3080EST#TRPBF

–40°C to 125°C

LCBN

LTCBM

8-Lead Plastic MSOP

LT3080Q

LT3080ET

3080

5-Lead Plastic DD-Pak

LT3080ET#PBF

5-Lead Plastic TO-220

LT3080IT#PBF

5-Lead Plastic TO-220

LT3080EST#PBF

3-Lead Plastic SOT-223

LT3080IST#PBF

LEAD BASED FINISH

LT3080EDD

LT3080IDD

LT3080IST#TRPBF

TAPE AND REEL

LT3080EDD#TR

LT3080IDD#TR

LT3080EMS8E#TR

LT3080IMS8E#TR

LT3080EQ#TR

3080

3-Lead Plastic SOT-223

PACKAGE DESCRIPTION

8-Lead (3mm x 3mm) Plastic DFN

8-Lead Plastic MSOP

–40°C to 125°C

TEMPERATURE RANGE

–40°C to 125°C

PART MARKING*

LCBN

LT3080EMS8E

LT3080IMS8E

LT3080EQ

LTCBM

8-Lead Plastic MSOP

LT3080Q

LT3080ET

3080

5-Lead Plastic DD-Pak

5-Lead Plastic TO-220

LT3080IQ

LT3080IQ#TR

LT3080ET

LT3080ET#TR

LT3080IT

LT3080IT#TR

5-Lead Plastic TO-220

LT3080EST

LT3080EST#TR

LT3080IST#TR

3-Lead Plastic SOT-223

LT3080IST

3080

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/

3080fc

3

LT3080

elecTrical characTerisTics ^Thel denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T_A= 25°C. (Note 11)

PARAMETER

CONDITIONS

MIN

TYP MAX UNITS

SET Pin Current

I

V

= 1V, V

≥ 1V, V

= 2.0V, I

= 1mA, T = 25°C

LOAD

9.90

9.80

10

10.10

10.20

µA

SET

IN

CONTROL

LOAD

J

l

≥ 2.0V, 1mA ≤ I

≤ 1.1A (Note 9)

Output Offset Voltage (V

– V

)

V

OS

DFN and MSOP Package

–2

–3.5

2

3.5

mV

OUT

SET

V

= 1V, V

= 2V, I = 1mA

OUT

IN

CONTROL

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

–5

–6

5

6

mV

Load Regulation

–0.1

0.6

nA

ΔI

= 1mA to 1.1A

SET

OS

LOAD

l

1.3

0.5

mV

ΔV

= 1mA to 1.1A (Note 8)

Line Regulation (Note 9)

DFN and MSOP Package

V

= 1V to 25V, V

= 2V to 25V, I = 1mA

LOAD

= 2V to 25V, I

0.1

0.003

nA/V

mV/V

ΔI

SET

IN

CONTROL

= 1V to 25V, V

= 1mA

ΔV

IN

LOAD

OS

l

Line Regulation (Note 9)

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

ΔI

V

= 1V to 26V, V

= 2V to 26V, I

= 1mA

0.1

0.003

0.5

nA/V

mV/V

SET

OS

IN

CONTROL

LOAD

ΔV

l

Minimum Load Current (Notes 3, 9)

V

IN

V

IN

V

IN

= V

= 10V

300

500

1

µA

mA

CONTROL

= 25V (DFN and MSOP Package)

= 26V (SOT-223, DD-Pak and T0-220 Package)

V

Dropout Voltage (Note 4)

Pin Current

I

= 100mA

= 1.1A

1.2

V

CONTROL

LOAD

l

1.35

1.6

l

Dropout Voltage (Note 4)

I

= 100mA

= 1.1A

100

350

200

500

mV

IN

LOAD

l

I

= 100mA

= 1.1A

4

17

6

30

mA

CONTROL

LOAD

l

Current Limit

V

= 5V, V

= 5V, V = 0V, V = –0.1V

OUT

1.1

1.4

40

1

A

IN

CONTROL

SET

Error Ampliﬁer RMS Output Noise (Note 6)

I

= 1.1A, 10Hz ≤ f ≤ 100kHz, C

= 10µF, C = 0.1µF

µV

LOAD

OUT

SET

RMS

Reference Current RMS Output Noise (Note 6)

Ripple Rejection

10Hz ≤ f ≤ 100kHz

nA

f = 120Hz, V

f = 10kHz

f = 1MHz

= 0.5V , I

= 0.2A, C = 0.1µF, C = 2.2µF

75

55

20

dB

RIPPLE

P-P LOAD

SET

OUT

Thermal Regulation, I

10ms Pulse

0.003

%/W

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 6: Output noise is lowered by adding a small capacitor across the

voltage setting resistor. Adding this capacitor bypasses the voltage setting

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

to error ampliﬁer noise (see Applications Information section).

Note 2: Unless otherwise speciﬁed, all voltages are with respect to V

.

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.

OUT

The LT3080 is tested and speciﬁed under pulse load conditions such that

T ≅ T . The LT3080E is tested at T = 25°C. Performance of the LT3080E

J

A

over the full –40°C and 125°C operating temperature range is assured by

design, characterization, and correlation with statistical process controls.

The LT3080I is guaranteed over the full –40°C to 125°C operating junction

temperature range.

Note 9: Current limit may decrease to zero at input-to-output differential

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

IN OUT

(SOT-223, DD-Pak and T0-220 Package). Operation at voltages for both IN

and V

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

CONTROL

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.

between input and output voltage is below the speciﬁed differential

(V –V ) voltage. Line and load regulation speciﬁcations are not

IN OUT

applicable when the device is in current limit.

Note 10: This IC includes overtemperature protection that is intended

to protect the device during momentary overload conditions. Junction

temperature will exceed the maximum operating junction temperature when

overtemperature protection is active. Continuous operation above the speciﬁed

maximum operating junction temperature may impair device reliability.

Note 4: For the LT3080, dropout is caused by either minimum control

voltage (V

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

CONTROL

IN

speciﬁed with respect to the output voltage. The speciﬁcations represent the

minimum input-to-output differential voltage required to maintain regulation.

Note 5: The V

pin current is the drive current required for the

CONTROL

Note 11: The SOT-223 package connects the IN and V

pins

CONTROL

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.

together internally. Therefore, test conditions for this pin follow the

conditions listed in the Electrical Characteristics Table.

V

CONTROL

3080fc

4

LT3080

Typical perForMance characTerisTics

Set Pin Current

Set Pin Current Distribution

Offset Voltage (V_OUT– V_SET

)

10.20

10.15

10.10

10.05

10.00

9.95

2.0

1.5

I

L

= 1mA

N = 13792

1.0

0.5

0

–0.5

–1.0

–1.5

–2.0

9.90

9.85

9.80

10.00

SET PIN CURRENT DISTRIBUTION (µA)

50 75

TEMPERATURE (°C)

9.80

9.90

10.10

10.20

50 75

TEMPERATURE (°C)

–50 –25

0

25

100 125 150

–50 –25

0

25

100 125 150

3080 G02

3080 G01

3080 G03

Offset Voltage Distribution

Offset Voltage

1.00

0.75

0.50

0.25

0

I

= 1mA

LOAD

N = 13250

T = 25°C

J

–0.25

–0.50

T = 125°C

J

0

–0.75

–1.00

–0.25

–0.50

–0.75

–1.00

–1.25

–1.50

–1.75

6

12

24

0.2

0.4

0.8

0

30

36*

0

1.0

1.2

0

18

0.6

–2

–1

1

2

INPUT-TO-OUTPUT VOLTAGE (V)

LOAD CURRENT (A)

V

DISTRIBUTION (mV)

OS

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

3080 G05

3080 G06

3080 G04

Dropout Voltage

(Minimum IN Voltage)

Load Regulation

Minimum Load Current

400

350

300

250

0

–0.1

–0.2

–0.3

–0.4

–0.5

–0.6

–0.7

–0.8

20

0.8

∆I

V

= 1mA TO 1.1A

OUT

LOAD

– V

= 2V

IN

10

0.7

T = 125°C

J

CHANGE IN REFERENCE CURRENT

V

– V

= 36V*

= 1.5V

0

0.6

0.5

0.4

0.3

0.2

0.1

0

IN, CONTROL

OUT

–10

–20

–30

–40

–50

–60

T = 25°C

J

CHANGE IN OFFSET VOLTAGE

200

150

(V

OUT

– V

)

SET

100

50

0

0.2

0.4

0.8

0

1.0

1.2

0.6

50 75

25

TEMPERATURE (°C)

50 75

TEMPERATURE (°C)

–50 –25

0

100 125 150

–50 –25

0

25

100 125 150

OUTPUT CURRENT (A)

3080 G09

3080 G07

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

3080 G08

3080fc

5

LT3080

Typical perForMance characTerisTics

Dropout Voltage

(Minimum IN Voltage)

Dropout Voltage (Minimum

V_CONTROLPin Voltage)

Dropout Voltage (Minimum

V_CONTROLPin Voltage)

1.6

1.4

1.2

1.0

400

350

300

250

200

150

100

50

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

T = –50°C

J

I

= 1.1A

LOAD

I

= 1.1A

LOAD

T = 125°C

J

I

= 1mA

LOAD

T = 25°C

J

I

= 500mA

LOAD

0.8

0.6

0.4

0.2

0

= 100mA

0

0.2

0.4

0.8

0

1.0

1.2

50 75

TEMPERATURE (°C)

0.6

–50 –25

0

25

100 125 150

–50 –25

50 75

TEMPERATURE (°C)

0

25

100 125 150

OUTPUT CURRENT (A)

3080 G11

3080 G10

3080 G12

Current Limit

Load Transient Response

75

50

1.6

1.4

1.2

1.0

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

V

C

V

= 1.5V

OUT

SET

IN

T = 25°C

J

= 0.1µF

= V

CONTROL

= 3V

SOT-223, DD-PAK

AND TO-220

25

0

–25

–50

400

300

200

100

0

C

= 10µF CERAMIC

OUT

0.8

0.6

C

= 2.2µF CERAMIC

OUT

MSOP

AND

DFN

0.4

0.2

0

V

= 7V

IN

OUT

= 0V

6

12

24

18

0

30

36*

0

5

10 15 20 25 30 35 40 45 50

50 75

25

TEMPERATURE (°C)

–50 –25

0

100 125 150

INPUT-TO-OUTPUT DIFFERENTIAL (V)

TIME (µs)

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

3080 G14

3080 G15

3080 G13

Turn-On Response

Load Transient Response

Line Transient Response

5

150

100

50

75

50

25

0

4

3

2

0

1

–50

–100

1.2

0.9

0.6

0.3

0

–25

–50

6

R

= 100k

= 0

SET

C

V

= 1.5V

= 10mA

= 2.2µF

OUT

0

R

C

= 1Ω

LOAD

OUT

I

LOAD

C

= 2.2µF CERAMIC

2.0

1.5

1.0

0.5

0

OUT

V

C

= V

= 3V

CONTROL

CERAMIC

= 0.1µF

SET

CERAMIC

IN

5

= 1.5V

C

OUT

SET

= 10µF CERAMIC

= 0.1µF

4

3

2

0

1

2

3

4

5

6

7

8

9

10

0

5

10 15 20 25 30 35 40 45 50

0

10 20 30 40 50 60 70 80 90 100

TIME (µs)

3080 G18

3080 G16

3080 G17

3080fc

6

LT3080

Typical perForMance characTerisTics

Residual Output Voltage with

Less Than Minimum Load

V_CONTROLPin Current

25

20

15

10

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

30

25

20

15

10

5

V

– V

= 2V

OUT

SET PIN = 0V

CONTROL

IN

– V

= 1V

OUT

V

IN

OUT

TEST

R

I

= 1.1A

LOAD

DEVICE IN

CURRENT LIMIT

T = –50°C

J

V

= 10V

IN

V

= 20V

IN

T = 25°C

J

V

= 5V

IN

T = 125°C

J

5

0

I

= 1mA

12

LOAD

6

0

18

24

30

36*

0

0.4

0.6

0.8

1.0

1.2

0

1k

2k

0.2

INPUT-TO-OUTPUT DIFFERENTIAL (V)

LOAD CURRENT (A)

R

TEST

(Ω)

3080 G19

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

3080 G20

3080 G21

Ripple Rejection, Dual Supply,

V_CONTROLPin

Ripple Rejection, Dual Supply,

IN Pin

Ripple Rejection, Single Supply

100

90

80

70

60

50

40

30

20

10

0

100

90

80

70

60

50

40

30

20

10

0

100

90

80

70

60

50

40

30

20

10

0

I

= 100mA

I

= 100mA

LOAD

I

= 1.1A

I

= 1.1A

LOAD

V

= V

+ 1V

OUT (NOMINAL)

IN

OUT (NOMINAL)

= V

+2V

V

C

= V

CONTROL

+ 1V

OUT (NOMINAL)

CONTROL

RIPPLE = 50mV

IN

OUT (NOMINAL)

= V

+2V

V

= V

OUT (NOMINAL)

P-P

+ 2V

100k

P-P

IN

CONTROL

C

I

= 2.2µF CERAMIC

= 1.1A

= 2.2µF CERAMIC

RIPPLE = 50mV

OUT

RIPPLE = 50mV

C

= 2.2µF CERAMIC

LOAD

P-P

OUT

10

100

1k

10k

100k

1M

10

100

1k

10k

1M

10

100

1k

10k

100k

1M

FREQUENCY (Hz)

3080 G24

3080 G22

3080 G23

Noise Spectral Density

Ripple Rejection (120Hz)

80

79

78

77

76

75

74

73

72

71

70

10k

1k

100

10

1

10

SINGLE SUPPLY OPERATION

1.0

V

= V

+ 2V

IN

OUT(NOMINAL)

RIPPLE = 500mV , f = 120Hz

P-P

I

= 1.1A

LOAD

C

= 0.1µF, C

= 2.2µF

SET

OUT

0.1

100k

–50

50

100 125

–25

0

25

75

150

10

100

1k

FREQUENCY (Hz)

10k

TEMPERATURE (°C)

3080 G26

3080 G25

3080fc

7

LT3080

Typical perForMance characTerisTics

Error Ampliﬁer Gain and Phase

Output Voltage Noise

20

15

300

250

200

150

100

50

10

V

OUT

100µV/DIV

I

L

= 1.1A

5

0

I

= 100mA

L

–5

3080 G27

TIME 1ms/DIV

V

OUT

R

= 1V

I

L

= 1.1A

–10

–15

–20

–25

–30

0

= 100k

= O.1µF

= 10µF

= 1.1A

SET

OUT

C

I

–50

–100

–150

–200

= 100mA

L

LOAD

10

100

1k

10k

100k

1M

FREQUENCY (Hz)

3080 G28

pin FuncTions ^{(DD/MS8E/Q/T/ST)}

V

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

OUT (Pins 1-3/Pins 1-3/Pin 3/Pin 3/Pin 2): This is the

power output of the device. There must be a minimum

load current of 1mA or the output may not regulate.

CONTROL

supply pin for the control circuitry of the device. The cur-

rent ﬂow into this pin is about 1.7% of the output current.

For the device to regulate, this voltage must be more than

1.2Vto1.35Vgreaterthantheoutputvoltage(seedropout

speciﬁcations).

SET (Pin 4/Pin 4/Pin 2/Pin 2/Pin 1): This pin is the input

to the error ampliﬁer and the regulation set point for

the device. A ﬁxed current of 10µA ﬂows out of this pin

through a single external resistor, which programs the

output voltage of the device. Output voltage range is zero

to the absolute maximum rated output voltage. Transient

performance can be improved by adding a small capacitor

from the SET pin to ground.

IN (Pins 7, 8/Pins 7, 8/Pin 5/Pin 5/Pin 3): This is the

collector to the power device of the LT3080. The output

load current is supplied through this pin. For the device

to regulate, the voltage at this pin must be more than

0.1V to 0.5V greater than the output voltage (see dropout

speciﬁcations).

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

DFN packages.

NC (Pin 6/Pin 6/Pin 1/Pin 1/NA): No Connection. No con-

nect pins have no connection to internal circuitry and may

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

be tied to V , V

, V

, GND or ﬂoated.

IN CONTROL OUT

3080fc

8

LT3080

block DiagraM

IN

V

CONTROL

10µA

+

–

3080 BD

SET

OUT

applicaTions inForMaTion

The LT3080 regulator is easy to use and has all the pro-

tection features expected in high performance regulators.

Included are short-circuit protection and safe operating

area protection, as well as thermal shutdown.

LT1086 have a change in loop gain with output voltage

as well as bandwidth changes when the adjustment pin

is bypassed to ground. For the LT3080, the loop gain is

unchanged by changing the output voltage or bypassing.

Output regulation is not ﬁxed at a percentage of the output

voltage but is a ﬁxed fraction of millivolts. Use of a true

current source allows all the gain in the buffer ampliﬁer

to provide regulation and none of that gain is needed to

amplify up the reference to a higher output voltage.

TheLT3080isespeciallywellsuitedtoapplicationsneeding

multiple rails. The new architecture adjusts down to zero

with a single resistor handling modern low voltage digital

IC’saswellasallowingeasyparalleloperationandthermal

managementwithoutheatsinks.Adjustingto“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.

The LT3080 has the collector of the output transistor

connected to a separate pin from the control input. Since

the dropout on the collector (IN pin) is only 350mV, two

supplies can be used to power the LT3080 to reduce dis-

sipation: a higher voltage supply for the control circuitry

and a lower voltage supply for the collector. This increases

efﬁciency and reduces dissipation. To further spread the

heat, a resistor can be inserted in series with the collector

to move some of the heat out of the IC and spread it on

the PC board.

A precision “0” TC 10µA internal current source is con-

nected to the noninverting input of a power operational

ampliﬁer. The power operational ampliﬁer provides a low

impedancebufferedoutputtothevoltageonthenoninvert-

ing input. A single resistor from the noninverting input to

ground sets the output voltage and if this resistor is set

to zero, zero output results. As can be seen, any output

voltage can be obtained from zero up to the maximum

deﬁned by the input power supply.

TheLT3080canbeoperatedintwomodes. Three-terminal

mode has the control pin connected to the power input pin

which gives a limitation of 1.35V dropout. Alternatively,

the “control” pin can be tied to a higher voltage and the

power IN pin to a lower voltage giving 350mV dropout

on the IN pin and minimizing the power dissipation. This

What is not so obvious from this architecture are the ben-

eﬁtsofusingatrueinternalcurrentsourceasthereference

asopposedtoabootstrappedreferenceinolderregulators.

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

to1.8V

allowsfora1.1Asupplyregulatingfrom2.5V

IN

OUT

or 1.8V to 1.2V

with low dissipation.

IN

OUT

3080fc

9

LT3080

applicaTions inForMaTion

If guardring techniques are used, this bootstraps any

stray capacitance at the SET pin. Since the SET pin is

a high impedance node, unwanted signals may couple

into the SET pin and cause erratic behavior. This will

be most noticeable when operating with minimum

output capacitors at full load current. The easiest way

to remedy this is to bypass the SET pin with a small

amount of capacitance from SET to ground, 10pF to

20pF is sufﬁcient.

IN

LT3080

V

CONTROL

+

–

+

V

CONTROL

IN

OUT

V

C

OUT

SET

R

C

SET

3080 F01

Stability and Output Capacitance

Figure 1. Basic Adjustable Regulator

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

Output Voltage

The LT3080 generates a 10µA reference current that ﬂows

out of the SET pin. Connecting a resistor from SET to

ground generates a voltage that becomes the reference

point for the error ampliﬁer (see Figure 1). The reference

voltage is a straight multiplication of the SET pin current

and the value of the resistor. Any voltage can be generated

and there is no minimum output voltage for the regulator.

A minimum load current of 1mA is required to maintain

regulation regardless of output voltage. For true zero

voltage output operation, this 1mA load current must be

returned to a negative supply voltage.

Larger

or less is recommended to prevent oscillations.

values of output capacitance decrease peak deviations

and provide improved transient response for larger load

current changes. Bypass capacitors, used to decouple

individual components powered by the LT3080, increase

the effective output capacitor value.

Forimprovementintransientperformance,placeacapaci-

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

With the low level current used to generate the reference

voltage, leakage paths to or from the SET pin can create

errors in the reference and output voltages. High quality

insulation should be used (e.g., Teﬂon, Kel-F); cleaning

of all insulating surfaces to remove ﬂuxes and other resi-

dues will probably be required. Surface coating may be

necessary to provide a moisture barrier in high humidity

environments.

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 speciﬁed with EIA temperature char-

acteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and

Y5V dielectrics are good for providing high capacitances

in a small package, but they tend to have strong volt-

age and temperature coefﬁcients as shown in Figures 2

and 3. When used with a 5V regulator, a 16V 10µF Y5V

capacitor can exhibit an effective value as low as 1µF to

2µF for the DC bias voltage applied and over the operating

temperature range. The X5R and X7R dielectrics result in

more stable characteristics and are more suitable for use

as the output capacitor. The X7R type has better stability

across temperature, while the X5R is less expensive and is

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.

3080fc

10

LT3080

applicaTions inForMaTion

20

ceramic capacitor the stress can be induced by vibrations

in the system or thermal transients.

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

0

X5R

Paralleling Devices

–20

LT3080’smaybeparalleledtoobtainhigheroutputcurrent.

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.

–40

–60

Y5V

–80

–100

0

8

12 14

2

4

6

10

16

DC BIAS VOLTAGE (V)

3080 F02

Figure 2. Ceramic Capacitor DC Bias Characteristics

Table 1. PC Board Trace Resistance

WEIGHT (oz)

10 mil WIDTH

54.3

20 mil WIDTH

27.1

40

20

1

2

27.1

13.6

Trace resistance is measured in mOhms/in

X5R

0

–20

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

–40

Y5V

–60

–80

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

–100

–50 –25

0

25

50

TEMPERATURE (°C)

75

100 125

3080 F03

V

LT3080

IN

Figure 3. Ceramic Capacitor Temperature Characteristics

V

CONTROL

+

–

availableinhighervalues.Carestillmustbeexercisedwhen

using X5R and X7R capacitors; the X5R and X7R codes

only specify operating temperature range and maximum

capacitancechangeovertemperature.Capacitancechange

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.

10mΩ

OUT

SET

V

LT3080

IN

V

IN

4.8V TO 28V

V

CONTROL

+

–

1µF

10mΩ

V

3.3V

2A

OUT

SET

165k

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

10µF

3080 F04

Figure 4. Parallel Devices

3080fc

11

LT3080

applicaTions inForMaTion

(5milliohmsforthetwodevicesinparallel)onlyaddsabout

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.

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.

While90°Cisanacceptableoperatingtemperatureforthese

devices, this is in 25°C ambient. For higher ambients, the

temperaturemustbecontrolledtopreventdevicetempera-

ture from exceeding 125°C. A 3-meter-per-second airﬂow

across the devices will decrease the device temperature

about 20°C providing a margin for higher operating ambi-

ent temperatures.

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.

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.

The ﬁrst test was done with approximately 0.7V input-

to-output and 1A per device. This gave a 700 milliwatt

dissipation in each device and a 2A output current. The

temperature rise above ambient is approximately 28°C

and both devices were within plus or minus 1°C. Both the

thermal and electrical sharing of these devices is excel-

lent. The thermograph in Figure 5 shows the temperature

distribution between these devices and the PC board

reaches ambient temperature within about a half an inch

from the devices.

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

The power is then increased with 1.7V across each device.

Thisgives1.7wattsdissipationineachdeviceandadevice

Figure 5. Temperature Rise at 700mW Dissipation

Figure 6. Temperature Rise at 1.7W Dissipation

3080fc

12

LT3080

applicaTions inForMaTion

from the error ampliﬁer must be considered, and the gain

created by using a resistor divider cannot be forgotten.

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.

Traditional low noise regulators bring the voltage refer-

ence out to an external pin (usually through a large value

resistor) to allow for bypassing and noise reduction of

reference noise. The LT3080 does not use a traditional

voltage reference like other linear regulators, but instead

uses a reference current. That current operates with typi-

When power is ﬁrst turned on, the input voltage rises and

the output follows the input, allowing the regulator to start

intoveryheavyloads. Duringstart-up, astheinputvoltage

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.

cal noise current levels of 3.2pA/√Hz (1nA

over the

RMS

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

–23

(k = Boltzmann’s constant, 1.38 • 10

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 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.

The LT3080 uses a unity-gain follower from the SET pin

to drive the output, and there is no requirement to use

a resistor to set the output voltage. Use a high accuracy

voltage reference placed at the SET pin to remove the er-

rors in output voltage due to reference current tolerance

and resistor tolerance. Active driving of the SET pin is

acceptable; the limitations are the creativity and ingenuity

of the circuit designer.

Oneproblemthatanormallinearregulatorseeswithrefer-

ence voltage noise is that noise is gained up along with the

output when using a resistor divider to operate at levels

higherthanthenormalreferencevoltage.WiththeLT3080,

the unity-gain follower presents no gain whatsoever from

the SET pin to the output, so noise ﬁgures do not increase

accordingly. Error ampliﬁer noise is typically 125nV/√Hz

Load Regulation

BecausetheLT3080isaﬂoatingdevice(thereisnoground

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

(40µV

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

RMS

IN

LT3080

another factor that is RMS summed in to give a ﬁnal noise

ﬁgure for the regulator.

V

CONTROL

PARASITIC

+

–

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.

RESISTANCE

R

P

R

P

R

P

OUT

LOAD

R

SET

Overload Recovery

3080 F07

LikemanyICpowerregulators,theLT3080hassafeoperat-

ing area (SOA) protection. The SOA protection decreases

Figure 7. Connections for Best Load Regulation

3080fc

13

LT3080

applicaTions inForMaTion

of the connections between the regulator and the load.

The data sheet speciﬁcation for load regulation is Kelvin

sensed at the pins of the package. Negative side sensing

is a true Kelvin connection, with the bottom of the voltage

setting resistor returned to the negative side of the load

(see Figure 7). Connected as shown, system load regula-

tion will be the sum of the LT3080 load regulation and the

parasitic line resistance multiplied by the output current.

It is important to keep the positive connection between

the regulator and load as short as possible and use large

wire or PC board traces.

Table 2. MSE Package, 8-Lead MSOP

COPPER AREA

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

TOPSIDE* BACKSIDE BOARD AREA

2

2500mm

55°C/W

57°C/W

60°C/W

65°C/W

2

1000mm

2

225mm

100mm

2

*Device is mounted on topside

Table 3. DD Package, 8-Lead DFN

COPPER AREA

THERMAL RESISTANCE

TOPSIDE* BACKSIDE BOARD AREA

(JUNCTION-TO-AMBIENT)

2

2500mm

60°C/W

62°C/W

65°C/W

68°C/W

Thermal Considerations

2

1000mm

The LT3080 has internal power and thermal limiting cir-

cuitry designed to protect it under overload conditions.

For continuous normal load conditions, maximum junc-

tion temperature must not be exceeded. It is important

to give consideration to all sources of thermal resistance

from junction to ambient. This includes junction-to-case,

case-to-heat sink interface, heat sink resistance or circuit

board-to-ambient as the application dictates. Additional

heat sources nearby must also be considered.

2

225mm

100mm

2

*Device is mounted on topside

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

COPPER AREA

THERMAL RESISTANCE

TOPSIDE* BACKSIDE BOARD AREA

(JUNCTION-TO-AMBIENT)

2

2500mm

48°C/W

56°C/W

62°C/W

2

1000mm

2

225mm

100mm

For surface mount devices, heat sinking is accomplished

by using the heat spreading capabilities of the PC board

anditscoppertraces.Surfacemountheatsinksandplated

through-holes can also be used to spread the heat gener-

ated by power devices.

2

*Device is mounted on topside

Table 5. Q Package, 5-Lead DD-Pak

COPPER AREA

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

Junction-to-case thermal resistance is speciﬁed from the

IC junction to the bottom of the case directly below the

die. This is the lowest resistance path for heat ﬂow. Proper

mounting is required to ensure the best possible thermal

ﬂow from this area of the package to the heat sinking

material. For the TO-220 package, thermal compound is

strongly recommended for mechanical connections to a

heat sink. A thermally conductive spacer can be used for

electrical isolation as long as the added contribution to

thermal resistance is considered. Note that the Tab or

Exposed Pad (depending on package) is electrically

connected to the output.

TOPSIDE* BACKSIDE BOARD AREA

2

2500mm

25°C/W

30°C/W

35°C/W

2

1000mm

2

125mm

*Device is mounted on topside

T Package, 5-Lead TO-220

Thermal Resistance (Junction-to-Case) = 3°C/W

Calculating Junction Temperature

Example: Given an output voltage of 0.9V, a 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

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.

2

temperature be for the DFN package on a 2500mm board

with topside copper area of 500mm ?

2

3080fc

14

LT3080

applicaTions inForMaTion

The power in the drive circuit equals:

Junction Temperature will be equal to:

T = T + P • θ (approximated using tables)

P

DRIVE

= (V

– V )(I

)

CONTROL

OUT CONTROL

J

A

TOTAL

JA

where I

is equal to I /60. I

is a function

canbefound

T = 50°C + 721mW • 64°C/W = 96°C

CONTROL

ofoutputcurrent. AcurveofI

OUT

CONTROL

J

vsI

CONTROL

OUT

In this case, the junction temperature is below the maxi-

mum rating, ensuring reliable operation.

in the Typical Performance Characteristics curves.

The power in the output transistor equals:

Reducing Power Dissipation

P

= (V – V )(I

)

OUTPUT

IN

OUT OUT

In some applications it may be necessary to reduce

the power dissipation in the LT3080 package without

sacriﬁcing output current capability. Two techniques are

available. The ﬁrst technique, illustrated in Figure 8, em-

ploys a resistor in series with the regulator’s input. The

voltagedropacrossR_SdecreasestheLT3080’sIN-to-OUT

differential voltage and correspondingly decreases the

LT3080’s power dissipation.

The total power equals:

= P + P

OUTPUT

P

TOTAL

DRIVE

The current delivered to the SET pin is negligible and can

be ignored.

V

= 3.630V (3.3V + 10%)

CONTROL(MAX CONTINUOUS)

= 1.575V (1.5V + 5%)

IN(MAX CONTINUOUS)

As an example, assume: V = V

= 5V, V

= 3.3V

IN

CONTROL

OUT

= 0.9V, I

= 1A, T = 50°C

A

OUT

and I

= 1A. Use the formulas from the Calculating

OUT(MAX)

Power dissipation under these conditions is equal to:

PDRIVE = (V – V )(I

Junction Temperature section previously discussed.

)

OUT CONTROL

CONTROL

WithoutseriesresistorR ,powerdissipationintheLT3080

S

equals:

I_OUT

1A

I_CONTROL

=

= 17mA

60 60

= (3.630V – 0.9V)(17mA) = 46mW

1A

60





P_TOTAL= 5V – 3.3V •

+ 5V – 3.3V • 1A

(

)

(

)









P

DRIVE

= 1.73W

= (V – V )(I )

OUT OUT

OUTPUT

IN

= (1.575V – 0.9V)(1A) = 675mW

If the voltage differential (V ) across the NPN pass

DIFF

transistor is chosen as 0.5V, then R equals:

S

Total Power Dissipation = 721mW

5V – 3.3V − 0.5V

R_S=

= 1.2Ω

1A

Power dissipation in the LT3080 now equals:

V

IN

V

C1

CONTROL

R

S

LT3080

IN

ʹ

1A

60





P_TOTAL= 5V – 3.3V •

+ 0.5V • 1A = 0.53W

(

)

(

)









+

–

TheLT3080’spowerdissipationisnowonly30%compared

to no series resistor. R dissipates 1.2W of power. Choose

OUT

S

V

OUT

appropriate wattage resistors to handle and dissipate the

power properly.

C2

SET

3080 F08

R

SET

Figure 8. Reducing Power Dissipation Using a Series Resistor

3080fc

15

LT3080

applicaTions inForMaTion

The second technique for reducing power dissipation,

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

LT3080. This resistor provides a parallel path for current

ﬂow, reducing the current ﬂowing through the LT3080.

This technique works well if input voltage is reasonably

constant and output load current changes are small. This

technique also increases the maximum available output

current at the expense of minimum load requirements.

The maximum total power dissipation is (5.5V – 3.2V) •

1A = 2.3W. However the LT3080 supplies only:

5.5V – 3.2V

1A –

= 0.36A

3.6Ω

Therefore, the LT3080’s power dissipation is only:

= (5.5V – 3.2V) • 0.36A = 0.83W

P

DIS

R dissipates 1.47W of power. As with the ﬁrst technique,

As an example, assume: V = V

= 5V, V

OUT(MAX)

=

IN(MAX)

P

IN

CONTROL

= 3.2V, I

choose appropriate wattage resistors to handle and dis-

sipate the power properly. With this conﬁguration, the

LT3080 supplies only 0.36A. Therefore, load current can

increase by 0.64A to 1.64A while keeping the LT3080 in

its normal operating range.

5.5V, V

= 3.3V, V

= 1A and

OUT

OUT(MIN)

than 90% of I

OUT(MIN)

I

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

P

= 630mA.

OUT(MIN)

Calculating R yields:

P

5.5V – 3.2V

R_P=

= 3.65Ω

0.63A

(5% Standard value = 3.6Ω)

V

IN

V

C1

CONTROL

LT3080

IN

R

P

+

–

OUT

V

OUT

C2

SET

3080 F09

R

SET

Figure 9. Reducing Power Dissipation Using a Parallel Resistor

3080fc

16

LT3080

Typical applicaTions

Higher Output Current

Adding Shutdown

MJ4502

V

IN

LT3080

V

IN

6V

50Ω

IN

LT3080

V

CONTROL

+

–

V

CONTROL

+

OUT

100µF

+

–

V

OUT

SET

R1

1µF

V

3.3V

5A

OUT

Q1

VN2222LL

Q2*

VN2222LL

ON OFF

1N4148

+

SET

4.7µF

100µF

332k

SHUTDOWN

3080 TA04

*Q2 INSURES ZERO OUTPUT

IN THE ABSENCE OF ANY

OUTPUT LOAD.

3080 TA02

Current Source

Low Dropout Voltage LED Driver

V

IN

LT3080

V

IN

C1

CONTROL

100mA

D1

10V

LT3080

IN

V

CONTROL

+

–

1µF

+

–

1Ω

OUT

I

OUT

0A TO 1A

OUT

SET

4.7µF

SET

R1

24.9k

100k

R2

2.49Ω

3080 TA03

3080 TA05

Using a Lower Value SET Resistor

V

IN

LT3080

IN

12V

V

CONTROL

+

–

C1

1µF

OUT

V

OUT

0.5V TO 10V

SET

R1

49.9k

1%

V

= 0.5V + 1mA • R

OUT

SET

R2

499Ω

1%

C

1mA

OUT

4.7µF

R

SET

10k

3080 TA06

3080fc

17

LT3080

Typical applicaTions

Coincident Tracking

IN

LT3080

V

CONTROL

IN

LT3080

+

–

V

CONTROL

OUT

V

OUT3

5V

IN

LT3080

V

IN

+

–

SET

4.7µF

7V TO 28V

169k

3080 TA07

V

CONTROL

OUT

V

OUT2

3.3V

+

–

SET

R2

C3

4.7µF

C1

1.5µF

80.6k

V

2.5V

1A

OUT1

OUT

SET

R1

C2

4.7µF

249k

Adding Soft-Start

IN

LT3080

V

IN

4.8V to 28V

V

CONTROL

+

–

D1

C1

1µF

1N4148

V

3.3V

1A

OUT

SET

R1

C

OUT

C2

0.01µF

4.7µF

332k

3080 TA08

Lab Supply

IN

LT3080

IN

LT3080

V

IN

12V TO 18V

V

CONTROL

+

–

+

–

+

15µF

1Ω

OUT

V

OUT

0V TO 10V

SET

R4

+

15µF

4.7µF

100µF

100k

0A TO 1A

1MEG

3080 TA09

3080fc

18

LT3080

Typical applicaTions

High Voltage Regulator

6.1V

10k

V

IN

50V

1N4148

IN

LT3080

BUZ11

V

CONTROL

+

–

10µF

V

OUT

1A

V

OUT

V

OUT

= 20V

= 10µA • R

SET

+

4.7µF

SET

R

SET

15µF

2MEG

3080 TA10

Ramp Generator

Reference Buffer

IN

LT3080

IN

LT3080

V

IN

V

IN

5V

V

CONTROL

V

CONTROL

+

–

+

–

1µF

OUT

V

*

OUT

INPUT

OUTPUT

C2

SET

4.7µF

3080 TA12

LT1019

4.7µF

C1

1µF

VN2222LL

1N4148

VN2222LL

1µF

GND

*MIN LOAD 0.5mA

3080 TA11

Ground Clamp

Boosting Fixed Output Regulators

LT3080

IN

LT3080

V

IN

V

EXT

+

V

CONTROL

–

20Ω

OUT

+

–

20mΩ

SET

OUT

1µF

20mΩ

42Ω*

OUT

3.3V

2.6A

OUT

LT1963-3.3

5V

1N4148

10µF

47µF

4.7µF

3080 TA14

5k

33k

3080 TA13

*4mV DROP ENSURES LT3080 IS

OFF WITH NO LOAD

MULTIPLE LT3080’S CAN BE USED

3080fc

19

LT3080

Typical applicaTions

Low Voltage, High Current Adjustable High Efﬁciency Regulator*

0.47µH

10k

PV

SV

SW

IN

+

2×

†

2.7V TO 5.5V

I

TH

LT3080

100µF

IN

+

12.1k

294k

2×

100µF

470pF

LTC3414

R

2.2MEG 100k

1000pF

T

2N3906

V

CONTROL

PGOOD

RUN/SS

+

–

V

FB

OUT

20mΩ

78.7k

124k

SYNC/MODE

SGND PGND

SET

IN

LT3080

V

CONTROL

+

–

*DIFFERENTIAL VOLTAGE ON LT3080

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

BE

OUT

20mΩ

†

0V TO 4V

4A

†

MAXIMUM OUTPUT VOLTAGE IS 1.5V

BELOW INPUT VOLTAGE

SET

IN

LT3080

V

CONTROL

+

–

OUT

20mΩ

SET

IN

LT3080

V

CONTROL

+

–

OUT

20mΩ

3080 TA15

SET

+

100µF

100k

3080fc

20

LT3080

Typical applicaTions

Adjustable High Efﬁciency Regulator*

CMDSH-4E

†

V

BOOST

SW

4.5V TO 25V

IN

10µF

1µF

LT3493

0.1µF

10µH

100k

IN

LT3080

SHDN

TP0610L

68µF

0.1µF

V

MBRM140

CONTROL

200k

+

–

FB

GND

†

OUT

0V TO 10V

1A

4.7µF

10k

3080 TA16

SET

1MEG

*DIFFERENTIAL VOLTAGE ON LT3080

10k

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

†

MAXIMUM OUTPUT VOLTAGE IS 2V

BELOW INPUT VOLTAGE

2 Terminal Current Source

C

COMP

*

IN

LT3080

V

CONTROL

+

–

R1

SET

100k

3080 TA17

1V

R1

I

=

*C

OUT

COMP

R1 ≤ 10Ω 10µF

R1 ≥ 10Ω 2.2µF

3080fc

21

LT3080

package DescripTion

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

DD Package

8-Lead Plastic DFN (3mm × 3mm)

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

0.70 ±0.05

3.5 ±0.05

2.10 ±0.05 (2 SIDES)

1.65 ±0.05

PACKAGE

OUTLINE

0.25 ± 0.05

0.50

BSC

2.38 ±0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

R = 0.125

0.40 ± 0.10

TYP

5

8

3.00 ±0.10

(4 SIDES)

1.65 ± 0.10

(2 SIDES)

PIN 1

TOP MARK

(NOTE 6)

(DD8) DFN 0509 REV C

4

1

0.25 ± 0.05

0.75 ±0.05

0.200 REF

0.50 BSC

2.38 ±0.10

BOTTOM VIEW—EXPOSED PAD

0.00 – 0.05

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

3080fc

22

LT3080

package DescripTion

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

MS8E Package

8-Lead Plastic MSOP, Exposed Die Pad

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

BOTTOM VIEW OF

EXPOSED PAD OPTION

1.88

(.074)

1

0.29

REF

1.68

0.889 ± 0.127

(.035 ± .005)

1.88 ± 0.102

(.074 ± .004)

(.066)

0.05 REF

DETAIL “B”

5.23

(.206)

MIN

3.20 – 3.45

1.68 ± 0.102

(.066 ± .004)

CORNER TAIL IS PART OF

THE LEADFRAME FEATURE.

FOR REFERENCE ONLY

(.126 – .136)

DETAIL “B”

8

NO MEASUREMENT PURPOSE

3.00 ± 0.102

0.52

(.0205)

REF

(.118 ± .004)

(NOTE 3)

0.65

(.0256)

BSC

0.42 ± 0.038

(.0165 ± .0015)

TYP

8

7 6 5

RECOMMENDED SOLDER PAD LAYOUT

3.00 ± 0.102

(.118 ± .004)

(NOTE 4)

4.90 ± 0.152

(.193 ± .006)

DETAIL “A”

0.254

(.010)

0° – 6° TYP

GAUGE PLANE

1

2

3

4

0.53 ± 0.152

(.021 ± .006)

1.10

(.043)

MAX

0.86

(.034)

REF

DETAIL “A”

0.18

(.007)

SEATING

PLANE

0.22 – 0.38

(.009 – .015)

TYP

0.1016 ± 0.0508

(.004 ± .002)

0.65

(.0256)

BSC

MSOP (MS8E) 0210 REV F

NOTE:

1. DIMENSIONS IN MILLIMETER/(INCH)

2. DRAWING NOT TO SCALE

3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.

MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE

5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX

6. EXPOSED PAD DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD

SHALL NOT EXCEED 0.254mm (.010") PER SIDE.

3080fc

23

LT3080

package DescripTion

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

Q Package

5-Lead Plastic DD-Pak

(Reference LTC DWG # 05-08-1461)

.060

(1.524)

TYP

.390 – .415

(9.906 – 10.541)

.060

(1.524)

.165 – .180

(4.191 – 4.572)

.256

(6.502)

.045 – .055

(1.143 – 1.397)

15° TYP

+.008

.004

–.004

.060

(1.524)

.059

(1.499)

TYP

.183

(4.648)

.330 – .370

(8.382 – 9.398)

+0.203

–0.102

0.102

(

)

.095 – .115

(2.413 – 2.921)

.075

(1.905)

.067

(1.702)

BSC

.050 ± .012

(1.270 ± 0.305)

.300

(7.620)

.013 – .023

(0.330 – 0.584)

+.012

.143

–.020

.028 – .038

+0.305

BOTTOM VIEW OF DD-PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

3.632

Q(DD5) 0502

(0.711 – 0.965)

(

)

–0.508

TYP

.420

.276

.080

.420

.350

.325

.205

.565

.320

.090

.042

.090

.042

.067

RECOMMENDED SOLDER PAD LAYOUT

NOTE:

RECOMMENDED SOLDER PAD LAYOUT

FOR THICKER SOLDER PASTE APPLICATIONS

1. DIMENSIONS IN INCH/(MILLIMETER)

2. DRAWING NOT TO SCALE

3080fc

24

LT3080

package DescripTion

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

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

.165 – .180

(4.191 – 4.572)

.147 – .155

(3.734 – 3.937)

DIA

.390 – .415

(9.906 – 10.541)

.045 – .055

(1.143 – 1.397)

.230 – .270

(5.842 – 6.858)

.570 – .620

(14.478 – 15.748)

.620

(15.75)

TYP

.460 – .500

(11.684 – 12.700)

.330 – .370

(8.382 – 9.398)

.700 – .728

(17.78 – 18.491)

.095 – .115

(2.413 – 2.921)

SEATING PLANE

.152 – .202

(3.861 – 5.131)

.155 – .195*

(3.937 – 4.953)

.260 – .320

(6.60 – 8.13)

.013 – .023

(0.330 – 0.584)

.067

BSC

.135 – .165

(3.429 – 4.191)

.028 – .038

(0.711 – 0.965)

(1.70)

* MEASURED AT THE SEATING PLANE

T5 (TO-220) 0801

3080fc

25

LT3080

package DescripTion

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

ST Package

3-Lead Plastic SOT-223

(Reference LTC DWG # 05-08-1630)

.248 – .264

(6.30 – 6.71)

.129 MAX

.114 – .124

(2.90 – 3.15)

.059 MAX

.264 – .287

(6.70 – 7.30)

.248 BSC

.130 – .146

(3.30 – 3.71)

.039 MAX

.059 MAX

.090

BSC

.181 MAX

RECOMMENDED SOLDER PAD LAYOUT

.033 – .041

(0.84 – 1.04)

.0905

(2.30)

BSC

10° – 16°

.010 – .014

10°

MAX

.071

(1.80)

MAX

(0.25 – 0.36)

10° – 16°

.0008 – .0040

(0.0203 – 0.1016)

.024 – .033

(0.60 – 0.84)

.012

(0.31)

MIN

.181

(4.60)

BSC

ST3 (SOT-233) 0502

3080fc

26

LT3080

revision hisTory ^{(Revision history begins at Rev B)}

REV

DATE

DESCRIPTION

PAGE NUMBER

B

6/10

Made minor updates to Features and Description sections

Revised Line Regulation Conditions and Note 2

Made minor text edits in Applications Information section

Added 200k resistor to drawing 3080 TA19 in Typical Applications section

Updated Package Description drawings

1

3

9

20

21, 22

2

C

9/11

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

Updated Note 2.

3

3080fc

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

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

27

LT3080

Typical applicaTion

Paralleling Regulators

IN

LT3080

V

CONTROL

+

–

20mΩ

OUT

SET

IN

LT3080

V

IN

4.8V TO 28V

V

CONTROL

+

–

20mΩ

V

3.3V

2A

OUT

1µF

SET

165k

10µF

3080 TA18

relaTeD parTs

PART NUMBER

DESCRIPTION

COMMENTS

LDOs

LT1086

1.5A Low Dropout Regulator

800mA Low Dropout Regulator

Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output

LT1117

1V Dropout, Adjustable or Fixed Output, DD-Pak, SOT-223 Packages

OK for Sinking and Sourcing, S0-8 and SOT-223 Packages

LT1118

LT1963A

1.5A Low Noise, Fast Transient Response LDO

340mV Dropout Voltage, Low Noise: 40µV

, V = 2.5V to 20V,

RMS IN

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

LT1965

1.1A Low Noise LDO

290mV Dropout Voltage, Low Noise 40µV , V = 1.8V to 20V,

RMS IN

V

= 1.2V to 19.5V, Stable with Ceramic Caps TO-220, DD-Pak,

OUT

MSOP and 3mm × 3mm DFN packages.

LTC^®3026

1.5A Low Input Voltage VLDO^TMRegulator

V : 1.14V to 3.5V (Boost Enabled), 1.14V to 5.5V (with External 5V),

IN

V

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

Q

DO

MSOP and DFN Packages

Switching Regulators

LT1976

High Voltage, 1.5A Step-Down Switching Regulator

f = 200kHz, I = 100µA, TSSOP-16E Package

Q

LTC3414

4A (I ), 4MHz Synchronous Step-Down DC/DC

95% Efﬁciency, V : 2.25V to 5.5V, V

= 0.8V, TSSOP Package

OUT

IN

OUT(MIN)

Converter

LTC3406/LTC3406B 600mA (I ), 1.5MHz Synchronous Step-Down DC/DC

95% Efﬁciency, V : 2.5V to 5.5V, V

= 0.6V, I = 20µA,

Q

OUT

IN

OUT(MIN)

Converter

I

< 1µA, ThinSOT^TMPackage

SD

LTC3411

1.25A (I ), 4MHz Synchronous Step-Down DC/DC

95% Efﬁciency, V : 2.5V to 5.5V, V

= 0.8V, I = 60µA,

Q

OUT

IN

OUT(MIN)

Converter

I

< 1µA, 10-Lead MS or DFN Packages

SD

3080fc

LT 0911 REV C • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

28

●

 LINEAR TECHNOLOGY CORPORATION 2007

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LT3080EMS8E#PBF
厂家：	Linear
描述：	LT3080 - Adjustable 1.1A Single Resistor Low Dropout Regulator; Package: MSOP; Pins: 8; Temperature Range: -40°C to 85°C 光电二极管输出元件调节器
文件：	总28页 (文件大小：370K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT3080EMS8E#PBF [Linear]

相关型号：

LT3080EMS8E#TR

LT3080EMS8E#TRPBF

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