ANALOG DEVICES LT 3080EMS8E, LT 3080 EST Datasheet

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Page 1

LT3080

Adjustable1.1A Single

Resistor Low Dropout

Regulator

FeaTures

Outputs May be Paralleled for Higher Current and

Heat Spreading

Output Current: 1.1A

Single Resistor Programs Output Voltage

1% Initial Accuracy of SET Pin Current

Output Adjustable to 0V

Low Output Noise: 40µV

Wide Input Voltage Range: 1.2V to 36V

Low Dropout Voltage: 350mV (Except SOT-223

(10Hz to 100kHz)

RMS

Package)

<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

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

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

applicaTions

High Current All Surface Mount Supply

High Efﬁciency Linear Regulator

Post Regulator for Switching Supplies

Low Parts Count Variable Voltage Supply

Low Output Voltage Power Supplies

DescripTion

The LT®3080 is a 1.1A low dropout linear regulator that can be paralleled to increase output current or spread heat in surface mounted boards. Architected as a precision current source and voltage follower allows this new regulator to be used in many applications requiring high current, adjustability to zero, and no heat sink. Also the device brings out the collector of the pass transistor to allow low dropout operation —down to 350 millivolts— when used with multiple supplies.

A key feature of the LT3080 is the capability to supply a wide output voltage range. By using a reference current through a single resistor, the output voltage is programmed to any level between zero and 36V. The LT3080 is stable with 2.2µF of capacitance on the output, and the IC uses small ceramic capacitors that do not require additional ESR as is common with other regulators.

Internal protection circuitry includes current limiting and thermal limiting. The LT3080 regulator is offered in the 8-lead MSOP (with an exposed pad for better thermal characteristics), a 3mm × 3mm DFN, 5-lead DD-Pak, TO-220 and a simple-to-use 3-lead SOT-223 version.

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.

Typical applicaTion

Variable Output Voltage 1.1A Supply

SET

LT3080

SET

OUT

+ –

= R

SET

1.2V TO 36V V

CONTROL

1µF

• 10µA

OUT

3080 TA01a

OUT

2.2µF

Set Pin Current Distribution

N = 13792

9.80

9.90

SET PIN CURRENT DISTRIBUTION (µA)

10.00

10.10

10.20

3080 G02

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Page 2

LT3080

absoluTe MaxiMuM raTings

CONTROL

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

(Note 1)(All Voltages Relative to V

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

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

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

Output Short-Circuit Duration .......................... Indeﬁnite

pin conFiguraTion

TOP VIEW

1OUT

OUT

SET

8-LEAD (3mm × 3mm) PLASTIC DFN

= 125°C, θJA = 64°C/W, θJC = 3°C/W

JMAX

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

OUT

DD PACKAGE

8 7

6 5

IN IN NC V

CONTROL

OUT

SET

MS8E PACKAGE

8-LEAD PLASTIC MSOP

= 125°C, θJA = 60°C/W, θJC = 10°C/W

JMAX

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

)

OUT

Operating Junction Temperature Range (Notes 2, 10)

E-, I-Grades ............................................ –40°C to 125°C

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

Lead Temperature (Soldering, 10 sec)

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

TOP VIEW

OUT

8 7 6 5

IN IN NC V

CONTROL

TAB IS

OUT

FRONT VIEW

5 4 3 2 1

Q PACKAGE

5-LEAD PLASTIC DD-PAK

= 125°C, θJA = 30°C/W, θJC = 3°C/W

JMAX

IN V

CONTROL

OUT SET NC

TAB IS

OUT

FRONT VIEW

5 4 3 2 1

T PACKAGE

5-LEAD PLASTIC TO-220

= 125°C, θJA = 40°C/W, θJC = 3°C/W

JMAX

IN V

CONTROL

OUT SET NC

FRONT VIEW

TAB IS

OUT

ST PACKAGE

3-LEAD PLASTIC SOT-223

*IN IS V

JMAX

AND IN TIED TOGETHER

CONTROL

= 125°C, θJA = 55°C/W, θJC = 15°C/W

IN*

OUT

SET

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LT3080

orDer inForMaTion

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

LT3080EDD#PBF LT3080EDD#TRPBF LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C LT3080IDD#PBF LT3080IDD#TRPBF LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C LT3080EMS8E#PBF LT3080EMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C LT3080IMS8E#PBF LT3080IMS8E#TRPBF LTCBM 8-Lead Plastic MSOP –40°C to 125°C LT3080EQ#PBF LT3080EQ#TRPBF LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C LT3080IQ#PBF LT3080IQ#TRPBF LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C LT3080ET#PBF LT3080ET#TRPBF LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C LT3080IT#PBF LT3080IT#TRPBF LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C LT3080EST#PBF LT3080EST#TRPBF 3080 3-Lead Plastic SOT-223 –40°C to 125°C

LT3080IST#PBF LT3080IST#TRPBF 3080 3-Lead Plastic SOT-223 –40°C to 125°C

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

LT3080EDD LT3080EDD#TR LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C LT3080IDD LT3080IDD#TR LCBN 8-Lead (3mm x 3mm) Plastic DFN –40°C to 125°C LT3080EMS8E LT3080EMS8E#TR LTCBM 8-Lead Plastic MSOP –40°C to 125°C LT3080IMS8E LT3080IMS8E#TR LTCBM 8-Lead Plastic MSOP –40°C to 125°C LT3080EQ LT3080EQ#TR LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C LT3080IQ LT3080IQ#TR LT3080Q 5-Lead Plastic DD-Pak –40°C to 125°C LT3080ET LT3080ET#TR LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C LT3080IT LT3080IT#TR LT3080ET 5-Lead Plastic TO-220 –40°C to 125°C LT3080EST LT3080EST#TR 3080 3-Lead Plastic SOT-223 –40°C to 125°C LT3080IST LT3080IST#TR 3080 3-Lead Plastic SOT-223 –40°C to 125°C Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/

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

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LT3080

The l denotes the speciﬁcations which apply over the full operating

elecTrical characTerisTics

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

PARAMETER CONDITIONS MIN TYP MAX UNITS

SET Pin Current I

Output Offset Voltage (V VIN = 1V, V

CONTROL

= 2V, I

OUT

– V

SET)

= 1mA

SETVIN

= 1V, V

≥ 1V, V

DFN and MSOP Package

CONTROL CONTROL

= 2.0V, I

= 1mA, TJ = 25°C

LOAD

≥ 2.0V, 1mA ≤ I

≤ 1.1A (Note 9)

LOAD

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

Load Regulation

Line Regulation (Note 9) DFN and MSOP Package

Line Regulation (Note 9) SOT-223, DD-Pak and T0-220 Package

Minimum Load Current (Notes 3, 9) V

Dropout Voltage (Note 4) I

CONTROL

Dropout Voltage (Note 4) I

Pin Current I

CONTROL

Current Limit V Error Ampliﬁer RMS Output Noise (Note 6) I

ΔI ΔV

ΔI

ΔV

SET

ΔI ΔI

VIN = 1V to 25V, V V

VIN = 1V to 26V, V V

V V

1mA to 1.1A

LOAD =

1mA to 1.1A (Note 8)

LOAD =

= 1V to 25V, V

= 1V to 26V, V

= V

CONTROL

= V

CONTROL

= V

CONTROL

= 100mA

LOAD

= 1.1A

LOAD

= 100mA

LOAD

= 1.1A

LOAD

= 100mA

LOAD

= 1.1A

LOAD

= 5V, V

= 1.1A, 10Hz ≤ f ≤ 100kHz, C

LOAD

CONTROL CONTROL

= 10V

= 25V (DFN and MSOP Package)

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

= 5V, V

CONTROL

= 2V to 25V, I = 2V to 25V, I

= 2V to 26V, I = 2V to 26V, I

= 0V, V

SET

OUT

= 1mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

= –0.1V

OUT

= 10µF, C

= 0.1µF 40 µV

SET

Reference Current RMS Output Noise (Note 6) 10Hz ≤ f ≤ 100kHz 1 nA Ripple Rejection f = 120Hz, V

RIPPLE

= 0.5V

P-P

, I

LOAD

= 0.2A, C

= 0.1µF, C

SET

OUT

= 2.2µF f = 10kHz f = 1MHz

Thermal Regulation, I

SET

10ms Pulse 0.003 %/W

9.90

9.80

–3.5

10 1010.10

10.20

–2

3.5

–5

–6

–0.1

0.6 1.3

0.1

0.5 nA/V

0.003

0.1

0.5 nA/V

0.003

l l l

l l

300 500

1.2

1.35 1.6 100

200

350

500

176 30

1.1 1.4 A

75 55 20

µA µA

mV mV

5 6

mV mV

mV/V

µA 1 1

mA mA

mV mV

mA mA

RMS

V V

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 V

OUT

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

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

over the full –40°C and 125°C operating temperature range is assured by design, characterization, and correlation with statistical process controls. The LT3080I is guaranteed over the full –40°C to 125°C operating junction temperature range.

Note 3: Minimum load current is equivalent to the quiescent current of the part. Since all quiescent and drive current is delivered to the output of the part, the minimum load current is the minimum current required to maintain regulation.

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

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

CONTROL

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

output transistor. This current will track output current with roughly a 1:60 ratio. The minimum value is equal to the quiescent current of the device.

Note 6: Output noise is lowered by adding a small capacitor across the voltage setting resistor. Adding this capacitor bypasses the voltage setting resistor shot noise and reference current noise; output noise is then equal to error ampliﬁer noise (see Applications Information section).

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

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

voltages (V

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

IN–VOUT

(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

between input and output voltage is below the speciﬁed differential (V

) voltage. Line and load regulation speciﬁcations are not

IN–VOUT

applicable when the device is in current limit. Note 10: This IC includes overtemperature protection that is intended

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

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

CONTROL

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

conditions listed in the Electrical Characteristics Table.

CONTROL

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Typical perForMance characTerisTics

LT3080

Set Pin Current Set Pin Current Distribution Offset Voltage (V

10.20

10.15

10.10

10.05

10.00

9.95

SET PIN CURRENT (µA)

9.90

9.85

9.80 –25

–50

TEMPERATURE (°C)

Offset Voltage Distribution

N = 13250

–2

–1

VOS DISTRIBUTION (mV)

N = 13792

100

125

150

3080 G01

9.80

9.90

SET PIN CURRENT DISTRIBUTION (µA)

10.00

10.10

10.20

3080 G02

Offset Voltage Offset Voltage

1.00 I

= 1mA

LOAD

0.75

0.50

0.25

–0.25

OFFSET VOLTAGE (mV)

–0.50

–0.75

3080 G04

–1.00

6 12 24

INPUT-TO-OUTPUT VOLTAGE (V)

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

36*

3080 G05

2.0

1.5

1.0

0.5

–0.5

OFFSET VOLTAGE (mV)

–1.0

–1.5

–2.0

–50

0.25

–0.25

–0.50

–0.75

–1.00

OFFSET VOLTAGE (mV)

–1.25

–1.50

–1.75

IL = 1mA

–25

Dropout Voltage

Load Regulation Minimum Load Current

∆I

= 1mA TO 1.1A

LOAD

– V

–0.1

–0.2

–0.3

–0.4

–0.5

–0.6

–0.7

CHANGE IN OFFSET VOLTAGE WITH LOAD (mV)

–0.8

–50

= 2V

OUT

CHANGE IN REFERENCE CURRENT

CHANGE IN OFFSET VOLTAGE

– V

)

SET

–25

OUT

TEMPERATURE (°C)

100

125

3080 G07

CHANGE IN REFERENCE CURRENT WITH LOAD (nA)

150

–10

–20

–30

–40

–50

–60

0.8

0.7

0.6

0.5

0.4

0.3

0.2

MINIMUM LOAD CURRENT (mA)

0.1

IN, CONTROL

–25

–50

*SEE NOTE 9 IN ELECTRICAL

TEMPERATURE (°C)

CHARACTERISTICS TABLE

– V

= 36V*

OUT

– V

= 1.5V

OUT

100

125

150

3080 G08

(Minimum IN Voltage)

400

350

) (mV)

OUT

300

– V

250

200

150

100

MINIMUM IN VOLTAGE (V

– V

OUT

TEMPERATURE (°C)

TJ = 125°C

0.2 0.4 0.8 LOAD CURRENT (A)

0.2 0.4 0.8

OUTPUT CURRENT (A)

TJ = 25°C

0.6

TJ = 125°C

0.6

)

SET

100

125

1.0

TJ = 25°C

1.0

150

3080 G03

1.2

3080 G06

1.2

3080 G09

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Page 6

LT3080

Typical perForMance characTerisTics

Dropout Voltage (Minimum IN Voltage)

400

350

) (mV)

OUT

300

– V

250

200

150

100

MINIMUM IN VOLTAGE (V

–25

–50

TEMPERATURE (°C)

Current Limit

1.6

1.4

1.2

1.0

0.8

0.6

CURRENT LIMIT (A)

0.4

VIN = 7V

0.2 = 0V

OUT

–25

–50

TEMPERATURE (°C)

Dropout Voltage (Minimum V

CONTROL

) (V)

1.6

OUT

1.4

= 1.1A

LOAD

= 500mA

LOAD

= 100mA

LOAD

100

125

150

3080 G10

– V

1.2

CONTROL

1.0

0.8

0.6

0.4

0.2

MINIMUM CONTROL VOLTAGE (V

Pin Voltage)

TJ = –50°C

TJ = 125°C

TJ = 25°C

0.2 0.4 0.8

0.6

OUTPUT CURRENT (A)

1.0

1.2

3080 G11

Current Limit

1.6

1.4

1.2

1.0

0.8

0.6

CURRENT LIMIT (A)

100

125

150

3080 G13

MSOP

0.4

0.2

6 12 24

INPUT-TO-OUTPUT DIFFERENTIAL (V)

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

SOT-223, DD-PAK AND TO-220

AND

DFN

TJ = 25°C

3080 G14

36*

Dropout Voltage (Minimum

) (V)

1.6

OUT

1.4

– V

1.2

CONTROL

1.0

0.8

0.6

0.4

0.2

MINIMUM CONTROL VOLTAGE (V

–50

CONTROL

–25

Pin Voltage)

LOAD

TEMPERATURE (°C)

Load Transient Response

–25

DEVIATION (mV)LOAD CURRENT (mA)

OUTPUT VOLTAGE

–50

400

300

200

100

OUT

= 2.2µF CERAMIC

OUT

105

LOAD

= 1mA

= 1.5V

OUT

= 0.1µF

SET

= V

= 10µF CERAMIC

30 35 45

2015

TIME (µs)

= 1.1A

100

CONTROL

125

150

3080 G12

= 3V

3080 G15

Load Transient Response Line Transient Response

150

100

–50

DEVIATION (mV)LOAD CURRENT (A)

OUTPUT VOLTAGE

–100

1.2

0.9

0.6

0.3

VIN = V V

OUT

= 0.1µF

SET

105

2015

TIME (µs)

30 35 45

= 3V

CONTROL

= 1.5V = 10µF CERAMIC

3080 G16

–25

DEVIATION (mV)

OUTPUT VOLTAGE

–50

IN/CONTROL VOLTAGE (V)

2010

4030

TIME (µs)

= 1.5V

OUT

= 10mA

LOAD

= 2.2µF

OUT

CERAMIC

= 0.1µF

SET

CERAMIC

60 70 90

100

3080 G17

Turn-On Response

2.0

1.5

1.0

0.5

OUTPUT VOLTAGE (V) INPUT VOLTAGE (V)

SET

LOAD

OUT

TIME (µs)

= 100k

= 0

= 1Ω

= 2.2µF CERAMIC

6 7 9

3080 G18

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Page 7

Typical perForMance characTerisTics

CONTROL PIN CURRENT (mA)

OUTPUT VOLTAGE (V)

0.8

RIPPLE REJECTION (dB)

100

RIPPLE REJECTION (dB)

100

RIPPLE REJECTION (dB)

ERROR AMPLIFIER NOISE

REFERENCE CURRENT NOISE

10k

CONTROL

*SEE NOTE 9 IN ELECTRICAL

CHARACTERISTICS TABLE

Pin Current

= 1.1A

LOAD

DEVICE IN CURRENT LIMIT

= 1mA

LOAD

12 18 24

INPUT-TO-OUTPUT DIFFERENTIAL (V)

Ripple Rejection, Single Supply

VIN = V RIPPLE = 50mV

OUT

= 1.1A

LOAD

= V

CONTROL

P-P

= 2.2µF CERAMIC

FREQUENCY (Hz)

LOAD

OUT (NOMINAL)

10k 100k10010 1k 1M

= 100mA

+ 2V

30 36*

3080 G19

3080 G22

CONTROL

V V

Ripple Rejection, Dual Supply, V

CONTROL

VIN = V

V C

RIPPLE = 50mV

Pin Current

– V

CONTROL

– V

= 1V

OUT

0.2 LOAD CURRENT (A)

LOAD

OUT (NOMINAL)

= V

CONTROL

= 2.2µF CERAMIC

OUT

= 2V

OUT

= –50°C

= 125°C

0.4 0.6 0.8

= 1.1A

+ 1V

OUT (NOMINAL)

P-P

FREQUENCY (Hz)

+2V

10k 100k10010 1k 1M

LOAD

= 25°C

1.0 1.2

= 100mA

3080 G23

3080 G20

LT3080

Residual Output Voltage with Less Than Minimum Load

SET PIN = 0V

0.7

0.6

0.5

0.4

0.3

0.2

0.1

VIN = 20V

Ripple Rejection, Dual Supply, IN Pin

100

VIN = V

OUT (NOMINAL)

CONTROL

RIPPLE = 50mV C

= 2.2µF CERAMIC

OUT

= 1.1A

LOAD

TEST

VIN = 10V

TEST

= V

OUT (NOMINAL)

P-P

FREQUENCY (Hz)

OUT

= 5V

(Ω)

+ 1V

+2V

10k 100k10010 1k 1M

2k1k

3080 G21

3080 G24

Ripple Rejection (120Hz)

RIPPLE REJECTION (dB)

–50

SINGLE SUPPLY OPERATION

= V

RIPPLE = 500mV I

LOAD

= 0.1µF, C

SET

–25 25

OUT(NOMINAL)

= 1.1A

P-P

= 2.2µF

OUT

TEMPERATURE (°C)

+ 2V

, f = 120Hz

100

125

3080 G25

150

Noise Spectral Density

100

SPECTRAL DENSITY (nV/√Hz)

FREQUENCY (Hz)

SPECTRAL DENSITY (pA/ √Hz)

100

1.0

10k 100k10010 1k

0.1

3080 G26

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Page 8

LT3080

GAIN (dB)

PHASE (DEGREES)

300

Typical perForMance characTerisTics

Output Voltage Noise

OUT

100µV/DIV

OUT

SET

= O.1µF

SET

OUT

LOAD

pin FuncTions

CONTROL

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

= 1V = 100k

= 10µF

= 1.1A

TIME 1ms/DIV

(DD/MS8E/Q/T/ST)

3080 G27

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 speciﬁcations).

IN (Pins 7, 8/Pins 7, 8/Pin 5/Pin 5/Pin 3): This is the collector to the power device of the LT3080. The output load current is supplied through this pin. For the device to regulate, the voltage at this pin must be more than

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

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

, V

CONTROL

, V

, GND or ﬂoated.

OUT

Error Ampliﬁer Gain and Phase

–10

–15

–20

–25

–30

–5

FREQUENCY (Hz)

IL = 1.1A

= 100mA

IL = 1.1A

IL = 100mA

10k 100k10010 1k 1M

250

200

150

100

–50

–100

–150

–200

3080 G28

OUT (Pins 1-3/Pins 1-3/Pin 3/Pin 3/Pin 2): This is the power output of the device. There must be a minimum load current of 1mA or the output may not regulate.

SET (Pin 4/Pin 4/Pin 2/Pin 2/Pin 1): This pin is the input to the error ampliﬁer and the regulation set point for the device. A ﬁxed current of 10µA ﬂows out of this pin through a single external resistor, which programs the output voltage of the device. Output voltage range is zero to the absolute maximum rated output voltage. Transient performance can be improved by adding a small capacitor from the SET pin to ground.

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

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

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Page 9

block DiagraM

CONTROL

applicaTions inForMaTion

LT3080

10µA

–

3080 BD

OUTSET

The LT3080 regulator is easy to use and has all the protection features expected in high performance regulators. Included are short-circuit protection and safe operating area protection, as well as thermal shutdown.

The LT3080 is especially well suited to applications needing multiple rails. The new architecture adjusts down to zero with a single resistor handling modern low voltage digital IC’s as well as allowing easy parallel operation and thermal management without heat sinks. Adjusting to “zero” output allows shutting off the powered circuitry and when the input is pre-regulated—such as a 5V or 3.3V input supply —external resistors can help spread the heat.

A precision “0” TC 10µA internal current source is connected to the noninverting input of a power operational ampliﬁer. The power operational ampliﬁer provides a low impedance buffered output to the voltage on the noninverting input. A single resistor from the noninverting input to ground sets the output voltage and if this resistor is set to zero, zero output results. As can be seen, any output voltage can be obtained from zero up to the maximum deﬁned by the input power supply.

What is not so obvious from this architecture are the beneﬁts of using a true internal current source as the reference as opposed to a bootstrapped reference in older regulators. A true current source allows the regulator to have gain and frequency response independent of the impedance on the positive input. Older adjustable regulators, such as the

LT1086 have a change in loop gain with output voltage as well as bandwidth changes when the adjustment pin is bypassed to ground. For the LT3080, the loop gain is unchanged by changing the output voltage or bypassing. Output regulation is not ﬁxed at a percentage of the output voltage but is a ﬁxed fraction of millivolts. Use of a true current source allows all the gain in the buffer ampliﬁer to provide regulation and none of that gain is needed to amplify up the reference to a higher output voltage.

The LT3080 has the collector of the output transistor connected to a separate pin from the control input. Since the dropout on the collector (IN pin) is only 350mV, two supplies can be used to power the LT3080 to reduce dissipation: a higher voltage supply for the control circuitry and a lower voltage supply for the collector. This increases efﬁciency and reduces dissipation. To further spread the heat, a resistor can be inserted in series with the collector to move some of the heat out of the IC and spread it on the PC board.

The LT3080 can be operated in two modes. Three-terminal mode has the control pin connected to the power input pin which gives a limitation of 1.35V dropout. Alternatively, the “control” pin can be tied to a higher voltage and the power IN pin to a lower voltage giving 350mV dropout on the IN pin and minimizing the power dissipation. This allows for a 1.1A supply regulating from 2.5V or 1.8V

to 1.2V

with low dissipation.

OUT

to 1.8V

OUT

3080fc

Page 10

LT3080

applicaTions inForMaTion

SET

LT3080

+ –

OUT

SET

OUT

3080 F01

CONTROL

Figure 1. Basic Adjustable Regulator

Output Voltage

The LT3080 generates a 10µA reference current that ﬂows out of the SET pin. Connecting a resistor from SET to ground generates a voltage that becomes the reference point for the error ampliﬁer (see Figure 1). The reference voltage is a straight

multiplication of the SET pin current and the value of the resistor. Any voltage can be generated and there is no minimum output voltage for the regulator. A minimum load current of 1mA is required to maintain regulation regardless of output voltage. For true zero voltage output operation, this 1mA load current must be returned to a negative supply voltage.

With the low level current used to generate the reference voltage, leakage paths to or from the SET pin can create errors in the reference and output voltages. High quality insulation should be used (e.g., Teﬂon, Kel-F); cleaning of all insulating surfaces to remove ﬂuxes and other 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 capacitance from SET to ground, 10pF to 20pF is sufﬁcient.

Stability and Output Capacitance

The LT3080 requires an output capacitor for stability. It is designed to be stable with most low ESR capacitors (typically ceramic, tantalum or low ESR electrolytic). A minimum output capacitor of 2.2µF with an ESR of 0.5Ω or less is recommended to prevent oscillations.

values of output capacitance decrease peak

Larger

deviations and provide improved transient response for larger load current changes. Bypass capacitors, used to decouple individual components powered by the LT3080, increase the effective output capacitor value.

For improvement in transient performance, place a capacitor across the voltage setting resistor. Capacitors up to 1µF can be used. This bypass capacitor reduces system noise as well, but start-up time is proportional to the time constant of the voltage setting resistor (R

in Figure 1)

SET

and SET pin bypass capacitor. Extra consideration must be given to the use of ceramic

capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior across temperature and applied voltage. The most common dielectrics used are speciﬁed with EIA temperature characteristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but they tend to have strong voltage and temperature 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

3080fc

Page 11

applicaTions inForMaTion

LT3080

–20

–40

–60

CHANGE IN VALUE (%)

–80

–100

2 6

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

X5R

Y5V

DC BIAS VOLTAGE (V)

3080 F02

Figure 2. Ceramic Capacitor DC Bias Characteristics

–20

–40

–60

CHANGE IN VALUE (%)

–80

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

–100

–50

–25 0

TEMPERATURE (°C)

25 75

X5R

Y5V

50 100 125

3080 F03

Figure 3. Ceramic Capacitor Temperature Characteristics

ceramic capacitor the stress can be induced by vibrations in the system or thermal transients.

Paralleling Devices

LT3080’s may be paralleled to obtain higher output current. The SET pins are tied together and the IN pins are tied together. This is the same whether it’s in three terminal mode or has separate input supplies. The outputs are connected in common using a small piece of PC trace as a ballast resistor to equalize the currents. PC trace resistance in milliohms/inch is shown in Table 1. Only a tiny area is needed for ballasting.

Table 1. PC Board Trace Resistance

WEIGHT (oz) 10 mil WIDTH 20 mil WIDTH

1 54.3 27.1 2 27.1 13.6

Trace resistance is measured in mOhms/in

The worse case offset between the set pin and the output of only ± 2 millivolts allows very small ballast resistors to be used. As shown in Figure 4, the two devices have a small 10 milliohm ballast resistor, which at full output current gives better than 80 percent equalized sharing of the current. The external resistance of 10 milliohms

CONTROL

LT3080

available in higher values. Care still must be exercised when using X5R and X7R capacitors; the X5R and X7R codes only specify operating temperature range and maximum capacitance change over temperature. Capacitance change due to DC bias with X5R and X7R capacitors is better than Y5V and Z5U capacitors, but can still be signiﬁcant enough to drop capacitor values below appropriate levels. Capacitor 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

4.8V TO 28V

+ –

SET

CONTROL

1µF

LT3080

+ –

SET

165k

OUT

10mΩ

3080 F04

3.3V 2A

10µF

OUT

Figure 4. Parallel Devices

3080fc

Page 12

LT3080

applicaTions inForMaTion

(5 milliohms for the two devices in parallel) only adds about 10 millivolts of output regulation drop at an output of 2A. Even with an output voltage as low as 1V, this only adds 1% to the regulation. Of course, more than two LT3080’s can be paralleled for even higher output current. They are spread out on the PC board, spreading the heat. Input resistors can further spread the heat if the input-to-output difference is high.

Thermal Performance

In this example, two LT3080 3mm × 3mm DFN devices are mounted on a 1oz copper 4-layer PC board. They are placed approximately 1.5 inches apart and the board is mounted vertically for convection cooling. Two tests were set up to measure the cooling performance and current sharing of these devices.

The ﬁrst test was done with approximately 0.7V inputto-output and 1A per device. This gave a 700 milliwatt dissipation in each device and a 2A output current. The temperature rise above ambient is approximately 28°C and both devices were within plus or minus 1°C. Both the thermal and electrical sharing of these devices is excellent. The thermograph in Figure 5 shows the temperature distribution between these devices and the PC board reaches ambient temperature within about a half an inch from the devices.

The power is then increased with 1.7V across each device. This gives 1.7 watts dissipation in each device and a device

temperature of about 90°C, about 65°C above ambient as shown in Figure 6. Again, the temperature matching between the devices is within 2°C, showing excellent tracking between the devices. The board temperature has reached approximately 40°C within about 0.75 inches of each device.

While 90°C is an acceptable operating temperature for these devices, this is in 25°C ambient. For higher ambients, the temperature must be controlled to prevent device temperature from exceeding 125°C. A 3-meter-per-second 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 devices can be paralleled for higher output current. Current sharing and thermal sharing is excellent, showing that acceptable operation can be had while keeping the peak temperatures below excessive operating temperatures on a board. This technique allows higher operating current linear regulation to be used in systems where it could never be used before.

Quieting the Noise

The LT3080 offers numerous advantages when it comes to dealing with noise. There are several sources of noise in a linear regulator. The most critical noise source for any LDO is the reference; from there, the noise contribution

Figure 5. Temperature Rise at 700mW Dissipation

Figure 6. Temperature Rise at 1.7W Dissipation

3080fc

Page 13

applicaTions inForMaTion

LT3080

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 reference out to an external pin (usually through a large value resistor) to allow for bypassing and noise reduction of reference noise. The LT3080 does not use a traditional voltage reference like other linear regulators, but instead uses a reference current. That current operates with typical 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

(k = Boltzmann’s constant, 1.38 • 10

–23

J/°K, and T is absolute temperature) which is RMS summed with the reference current noise. To lower reference noise, the voltage setting resistor may be bypassed with a capacitor, though this causes start-up time to increase as a factor of the RC time constant.

The LT3080 uses a unity-gain follower from the SET pin to drive the output, and there is no requirement to use a resistor to set the output voltage. Use a high accuracy voltage reference placed at the SET pin to remove the errors in output voltage due to reference current tolerance and resistor tolerance. Active driving of the SET pin is acceptable; the limitations are the creativity and ingenuity of the circuit designer.

current limit as the input-to-output voltage increases and keeps the power dissipation at safe levels for all values of input-to-output voltage. The LT3080 provides some output current at all values of input-to-output voltage up to the device breakdown. See the Current Limit curve in the Typical Performance Characteristics.

When power is ﬁrst turned on, the input voltage rises and the output follows the input, allowing the regulator to start into very heavy loads. During start-up, as the input voltage is rising, the input-to-output voltage differential is small, allowing the regulator to supply large output currents. With a high input voltage, a problem can occur wherein removal of an output short will not allow the output voltage to recover. Other regulators, such as the LT1085 and LT1764A, also exhibit this phenomenon so it is not unique to the LT3080.

The problem occurs with a heavy output load when the input voltage is high and the output voltage is low. Common situations are immediately after the removal of a short circuit. The load line for such a load may intersect the output current curve at two points. If this happens, there are two stable operating points for the regulator. With this double intersection, the input power supply may need to be cycled down to zero and brought up again to make the output recover.

One problem that a normal linear regulator sees with reference voltage noise is that noise is gained up along with the output when using a resistor divider to operate at levels higher than the normal reference voltage. With the LT3080, the unity-gain follower presents no gain whatsoever from the SET pin to the output, so noise ﬁgures do not increase accordingly. Error ampliﬁer noise is typically 125nV/√Hz (40µV

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

RMS

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 characteristics for both the reference current and error ampliﬁer over the 10Hz to 100kHz bandwidth.

Overload Recovery

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

Load Regulation

Because the LT3080 is a ﬂoating device (there is no ground pin on the part, all quiescent and drive current is delivered to the load), it is not possible to provide true remote load sensing. Load regulation will be limited by the resistance

SET

LT3080

+ –

SET

RESISTANCE

OUT

PARASITIC

LOAD

3080 F07

3080fc

CONTROL

Figure 7. Connections for Best Load Regulation

Page 14

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 regulation will be the sum of the LT3080 load regulation and the parasitic line resistance multiplied by the output current. It is important to keep the positive connection between the regulator and load as short as possible and use large wire or PC board traces.

Thermal Considerations

The LT3080 has internal power and thermal limiting circuitry designed to protect it under overload conditions. For continuous normal load conditions, maximum junction temperature must not be exceeded. It is important to give consideration to all sources of thermal resistance from junction to ambient. This includes junction-to-case, case-to-heat sink interface, heat sink resistance or circuit board-to-ambient as the application dictates. Additional heat sources nearby must also be considered.

For surface mount devices, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Surface mount heat sinks and plated through-holes can also be used to spread the heat generated by power devices.

Junction-to-case thermal resistance is speciﬁed from the IC junction to the bottom of the case directly below the die. This is the lowest resistance path for heat ﬂow. Proper mounting is required to ensure the best possible thermal ﬂow from this area of the package to the heat sinking material. For the TO-220 package, thermal compound is strongly recommended for mechanical connections to a heat sink. A thermally conductive spacer can be used for electrical isolation as long as the added contribution to thermal resistance is considered. Note that the Tab or

Exposed Pad (depending on package) is electrically connected to the output.

The following tables list thermal resistance for several different copper areas given a ﬁxed board size. All measurements were taken in still air on two-sided 1/16” FR-4 board with one ounce copper.

Table 2. MSE Package, 8-Lead MSOP

COPPER AREA

TOPSIDE* BACKSIDE BOARD AREA

2500mm 1000mm

225mm 100mm

*Device is mounted on topside

2500mm22500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

55°C/W 57°C/W 60°C/W 65°C/W

Table 3. DD Package, 8-Lead DFN

COPPER AREA

TOPSIDE* BACKSIDE BOARD AREA

2500mm 1000mm

225mm 100mm

*Device is mounted on topside

2500mm22500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

60°C/W 62°C/W 65°C/W 68°C/W

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

COPPER AREA

TOPSIDE* BACKSIDE BOARD AREA

2500mm 1000mm

225mm 100mm

*Device is mounted on topside

2500mm22500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

48°C/W 48°C/W 56°C/W 62°C/W

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

COPPER AREA

TOPSIDE* BACKSIDE BOARD AREA

2500mm 1000mm

125mm

*Device is mounted on topside

2500mm22500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)

25°C/W 30°C/W 35°C/W

T Package, 5-Lead TO-220

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

Calculating Junction Temperature

Example: Given an output voltage of 0.9V, a V

CONTROL

voltage of 3.3V ±10%, an IN voltage of 1.5V ±5%, output current range from 1mA to 1A and a maximum ambient temperature of 50°C, what will the maximum junction

temperature be for the DFN package on a 2500mm

with topside copper area of 500mm

board

3080fc

Page 15

−

applicaTions inForMaTion

LT3080

The power in the drive circuit equals:

DRIVE

CONTROL

= (V

CONTROL

is equal to I

P where I

of output current. A curve of I

– V

)(I

OUT

/60. I

OUT

CONTROL

vs I

)

is a function

can be found

OUT

in the Typical Performance Characteristics curves. The power in the output transistor equals: P

OUTPUT

= (VIN – V

OUT

)(I

OUT

) The total power equals: P

TOTAL

= P

DRIVE

+ P

OUTPUT

The current delivered to the SET pin is negligible and can be ignored.

CONTROL(MAX CONTINUOUS)

IN(MAX CONTINUOUS)

OUT

= 0.9V, I

= 1A, TA = 50°C

OUT

= 3.630V (3.3V + 10%)

= 1.575V (1.5V + 5%)

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

P P P

CONTROL

DRIVE

OUTPUT

= (3.630V – 0.9V)(17mA) = 46mW

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

CONTROL

OUT

– V

1A 60

OUT

= 17mA

)(I

OUT

)(I

CONTROL

)

Total Power Dissipation = 721mW

Junction Temperature will be equal to:

= TA + P

= 50°C + 721mW • 64°C/W = 96°C

• θJA (approximated using tables)

TOTAL

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

Reducing Power Dissipation

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

decreases the LT3080’s IN-to-OUT

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

As an example, assume: VIN = V and I

OUT(MAX)

= 1A. Use the formulas from the Calculating

CONTROL

= 5V, V

OUT

= 3.3V

Junction Temperature section previously discussed. Without series resistor R

, power dissipation in the LT3080

equals:



TOTAL

= 5V – 3.3V

( )



•









+ 5V – 3.3V

( )

• 1A

= 1.73W

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

) across the NPN pass

DIFF

equals:

0.5V

= 1.2Ω





•

dissipates 1.2W of power. Choose

+ 0.5V

 

( )

 

• 1A = 0.53W

3080fc

5V – 3.3V

RS=

CONTROL

LT3080

VINʹ

Power dissipation in the LT3080 now equals:

TOTAL

= 5V – 3.3V

( )

+ –

SET

Figure 8. Reducing Power Dissipation Using a Series Resistor

OUT

3080 F08

OUT

The LT3080’s power dissipation is now only 30% compared to no series resistor. R appropriate wattage resistors to handle and dissipate the power properly.

Page 16

LT3080

5.5V – 3.2V

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.

As an example, assume: V

5.5V, V I

OUT(MIN)

than 90% of I Calculating R

RP=

= 3.3V, V

OUT

OUT(MIN)

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

OUT(MIN)

yields:

0.63A

= 630mA.

= 3.65Ω

= V

= 3.2V, I

CONTROL

= 5V, V

OUT(MAX)

IN(MAX)

= 1A and

(5% Standard value = 3.6Ω)

CONTROL

LT3080

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

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

1A –

3.6Ω

= 0.36A

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

= (5.5V – 3.2V) • 0.36A = 0.83W

DIS

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

choose appropriate wattage resistors to handle and dissipate 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.

OUT

3080 F09

OUT

+ –

SET

Figure 9. Reducing Power Dissipation Using a Parallel Resistor

3080fc

Page 17

Typical applicaTions

LT3080

Higher Output Current

50Ω

MJ4502

CONTROL

LT3080

SET

332k

+ –

OUT

4.7µF

OUT

3.3V 5A

100µF

3080 TA02

ON OFF

SHUTDOWN

100µF

1µF

Adding Shutdown

CONTROL

Q1 VN2222LL

LT3080

+ –

SET

1N4148

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

OUT

Q2* VN2222LL

3080 TA04

Current Source Low Dropout Voltage LED Driver

10V

LT3080

CONTROL

LT3080

CONTROL

100mA

1µF

SET

–

100k

OUT

1Ω

OUT

0A TO 1A

4.7µF

3080 TA03

SET

24.9k

+ –

OUT

2.49Ω

3080 TA05

12V

Using a Lower Value SET Resistor

LT3080

CONTROL

SET

49.9k 1%

R 10k

SET

–

1mA

OUT

R2 499Ω 1%

3080 TA06

OUT

0.5V TO 10V

OUT

4.7µF

= 0.5V + 1mA • R

OUT

SET

3080fc

C1 1µF

Page 18

LT3080

Typical applicaTions

Coincident Tracking

7V TO 28V

SET

169k

LT3080

4.7µF

+ –

OUT2

3.3V

OUT

OUT3

4.7µF

3080 TA07

CONTROL

SET R2

80.6k

4.7µF

LT3080

+ –

OUT1

2.5V 1A

OUT

CONTROL

LT3080

CONTROL

SET

R1 249k

–

OUT

1.5µF

Adding Soft-Start

4.8V to 28V

CONTROL

LT3080

12V TO 18V

SET

R1 332k

+ –

OUT

3080 TA08

OUT

3.3V 1A

OUT

4.7µF

C1 1µF

D1 1N4148

0.01µF

Lab Supply

SETSET

R4 1MEG

LT3080

+ –

OUTOUT

4.7µF 100µF

V 0V TO 10V

3080 TA09

OUT

CONTROL

15µF

LT3080

+ –

1Ω

100k

0A TO 1A

CONTROL

15µF

ININ

3080fc

Page 19

Typical applicaTions

LT3080

High Voltage Regulator

SET

2MEG

6.1V

LT3080

+ –

4.7µF

3080 TA11

OUT

4.7µF

OUT

INPUT

LT1019

GND

OUT

3080 TA10

CONTROL

= 20V

OUT

= 10µA • R

OUT

Reference Buffer

OUTPUT

SET

LT3080

+ –

C1 1µF

SET

OUT

*MIN LOAD 0.5mA

4.7µF

3080 TA12

OUT

10k

50V

1N4148

BUZ11

CONTROL

10µF

15µF

Ramp Generator

SET

LT3080

+ –

1µF

OUT

1N4148

1µF

CONTROL

VN2222LL VN2222LL

Ground Clamp

LT3080

+ –

1N4148

OUT

3080 TA13

20Ω

4.7µF

EXT

OUT

10µF

*4mV DROP ENSURES LT3080 IS OFF WITH NO LOAD

MULTIPLE LT3080’S CAN BE USED

LT1963-3.3

CONTROL

1µF

Boosting Fixed Output Regulators

LT3080

+ –

SET

20mΩ

42Ω* 47µF

33k

OUT

20mΩ

3080 TA14

3.3V

2.6A

OUT

3080fc

Page 20

LT3080

Typical applicaTions

Low Voltage, High Current Adjustable High Efﬁciency Regulator*

2.7V TO 5.5V

†

100µF

2×

2.2MEG 100k

1000pF

LTC3414

PGOOD RUN/SS

SYNC/MODE

SGND PGND

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

†

MAXIMUM OUTPUT VOLTAGE IS 1.5V

BELOW INPUT VOLTAGE

0.47µH

12.1k

294k

78.7k

124k

OF THE 2N3906 PNP.

470pF

2× 100µF

2N3906

10k

CONTROL

LT3080

+ –

SET

LT3080

OUT

20mΩ

+ –

SET

LT3080

OUT

20mΩ

0V TO 4V 4A

†

+ –

SET

OUT

20mΩ

CONTROL

LT3080

+ –

SET

100k

3080 TA15

OUT

20mΩ

100µF

3080fc

Page 21

Typical applicaTions

CMDSH-4E

LT3080

Adjustable High Efﬁciency Regulator*

4.5V TO 25V

†

10µF

1µF

0.1µF

BOOST

100k

LT3493

GND

SHDN

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

†

MAXIMUM OUTPUT VOLTAGE IS 2V

BELOW INPUT VOLTAGE

0.1µF 10µH

MBRM140

10k

2 Terminal Current Source

COMP

68µF

200k

TP0610L

CONTROL

10k

LT3080

SET

1MEG

–

3080 TA16

OUT

0V TO 10V 1A

4.7µF

†

CONTROL

LT3080

+ –

SET

COMP

R1 ≤ 10Ω 10µF R1 ≥ 10Ω 2.2µF

100k

3080 TA17

OUT

3080fc

Page 22

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

1.65 ±0.05 (2 SIDES)2.10 ±0.05

PACKAGE OUTLINE

0.25 ± 0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

PIN 1

TOP MARK

(NOTE 6)

0.200 REF

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

0.50 BSC

2.38 ±0.05

3.00 ±0.10 (4 SIDES)

0.75 ±0.05

0.00 – 0.05

1.65 ± 0.10 (2 SIDES)

R = 0.125

TYP

0.25 ± 0.05

2.38 ±0.10

BOTTOM VIEW—EXPOSED PAD

0.40 ± 0.10

0.50 BSC

(DD8) DFN 0509 REV C

3080fc

Page 23

package DescripTion

MS8E Package

8-Lead Plastic MSOP, Exposed Die Pad

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

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

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)

1.68

(.066)

DETAIL “B”

0.52

(.0205)

REF

3.00 ± 0.102 (.118 ± .004)

(NOTE 4)

0.86

(.034)

REF

0.1016 ± 0.0508 (.004 ± .002)

MSOP (MS8E) 0210 REV F

CORNER TAIL IS PART OF

THE LEADFRAME FEATURE.

NO MEASUREMENT PURPOSE

1.88 ± 0.102

(.074 ± .004)

5.23

(.206)

MIN

1.68 ± 0.102

(.066 ± .004)

0.42 ± 0.038

(.0165 ± .0015)

TYP

RECOMMENDED SOLDER PAD LAYOUT

0.254 (.010)

GAUGE PLANE

0.18

(.007)

NOTE:

1. DIMENSIONS IN MILLIMETER/(INCH)

2. DRAWING NOT TO SCALE

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

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

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

6. EXPOSED PAD DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE.

DETAIL “A”

0.65

(.0256)

BSC

0° – 6° TYP

DETAIL “A”

0.889 ± 0.127 (.035 ± .005)

(.126 – .136)

0.53 ± 0.152

(.021 ± .006)

SEATING

PLANE

3.20 – 3.45

3.00 ± 0.102 (.118 ± .004)

(NOTE 3)

4.90 ± 0.152 (.193 ± .006)

(.043)

0.22 – 0.38

(.009 – .015)

TYP

1.10

MAX

1 2

0.65

(.0256)

BSC

LT3080

0.29 REF

0.05 REF

DETAIL “B”

FOR REFERENCE ONLY

3080fc

Page 24

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)

.256

(6.502)

.060

(1.524)

.300

(7.620)

BOTTOM VIEW OF DD-PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

(1.524)

(1.905)

.060

.075

.183

(4.648)

.060

(1.524)

TYP

.330 – .370

(8.382 – 9.398)

.143

3.632

( )

.420

+.012 –.020

+0.305 –0.508

.350

.565

(9.906 – 10.541)

.028 – .038

(0.711 – 0.965)

TYP

.080

.390 – .415

15° TYP

.067

(1.702)

BSC

.205

.165 – .180

(4.191 – 4.572)

.420 .276

.059

(1.499)

TYP

.013 – .023

(0.330 – 0.584)

.325

.565

.045 – .055

(1.143 – 1.397)

+.008

.004

–.004

+0.203

0.102

( )

–0.102

.095 – .115

(2.413 – 2.921)

.050 ± .012

(1.270 ± 0.305)

Q(DD5) 0502

.067

RECOMMENDED SOLDER PAD LAYOUT NOTE:

1. DIMENSIONS IN INCH/(MILLIMETER)

2. DRAWING NOT TO SCALE

.042

.090

.320

.090

.067

RECOMMENDED SOLDER PAD LAYOUT

FOR THICKER SOLDER PASTE APPLICATIONS

.042

3080fc

Page 25

package DescripTion

.165 – .180

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)

LT3080

.390 – .415

(9.906 – 10.541)

.460 – .500

(11.684 – 12.700)

.067

BSC

(1.70)

.147 – .155

(3.734 – 3.937)

.230 – .270

(5.842 – 6.858)

.330 – .370

(8.382 – 9.398)

.028 – .038

(0.711 – 0.965)

DIA

.570 – .620

(14.478 – 15.748)

.260 – .320

(6.60 – 8.13)

SEATING PLANE

.152 – .202

(3.861 – 5.131)

(4.191 – 4.572)

.700 – .728

(17.78 – 18.491)

.135 – .165

(3.429 – 4.191)

.620

(15.75)

TYP

.045 – .055

(1.143 – 1.397)

.095 – .115

(2.413 – 2.921)

.155 – .195*

(3.937 – 4.953)

.013 – .023

(0.330 – 0.584)

* MEASURED AT THE SEATING PLANE

T5 (TO-220) 0801

3080fc

Page 26

LT3080

.248 – .264

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)

.264 – .287

(6.70 – 7.30)

.130 – .146

(3.30 – 3.71)

.071

(1.80)

MAX

.0905

(2.30)

BSC

(6.30 – 6.71)

.114 – .124

(2.90 – 3.15)

.024 – .033

(0.60 – 0.84)

.181

(4.60)

BSC

.033 – .041

(0.84 – 1.04)

.012

(0.31)

MIN

.059 MAX

10°

MAX

.129 MAX

.059 MAX

.181 MAX

RECOMMENDED SOLDER PAD LAYOUT

10° – 16°

.0008 – .0040

(0.0203 – 0.1016)

.248 BSC

.039 MAX

.090 BSC

.010 – .014

(0.25 – 0.36)

10° – 16°

ST3 (SOT-233) 0502

3080fc

Page 27

LT3080

revision hisTory

REV DATE DESCRIPTION PAGE NUMBER

B 6/10 Made minor updates to Features and Description sections

Revised Line Regulation Conditions and Note 2 Made minor text edits in Applications Information section Added 200k resistor to drawing 3080 TA19 in Typical Applications section Updated Package Description drawings

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

Updated Note 2.

(Revision history begins at Rev B)

1 3 9

21, 22

2 3

Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

3080fc

Page 28

LT3080

Typical applicaTion

Paralleling Regulators

relaTeD parTs

4.8V TO 28V

LT3080

CONTROL

+ –

SET

LT3080

CONTROL

OUT

20mΩ

+ –

1µF

SET

165k

OUT

20mΩ

3080 TA18

10µF

OUT

3.3V 2A

PART NUMBER DESCRIPTION COMMENTS

LDOs

LT1086 1.5A Low Dropout Regulator Fixed 2.85V, 3.3V, 3.6V, 5V and 12V Output LT1117 800mA Low Dropout Regulator 1V Dropout, Adjustable or Fixed Output, DD-Pak, SOT-223 Packages LT1118 800mA Low Dropout Regulator OK for Sinking and Sourcing, S0-8 and SOT-223 Packages LT1963A 1.5A Low Noise, Fast Transient Response LDO 340mV Dropout Voltage, Low Noise: 40µV

, VIN = 2.5V to 20V,

RMS

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

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

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

OUT

, VIN = 1.8V to 20V,

RMS

MSOP and 3mm × 3mm DFN packages.

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

LTC

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

MSOP and DFN Packages

Switching Regulators

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

), 4MHz Synchronous Step-Down DC/DC

OUT

95% Efﬁciency, VIN: 2.25V to 5.5V, V

= 100µA, TSSOP-16E Package

OUT(MIN)

= 0.8V, TSSOP Package

Converter

LTC3406/LTC3406B 600mA (I

Converter

LTC3411 1.25A (I

Converter

), 1.5MHz Synchronous Step-Down DC/DC

OUT

), 4MHz Synchronous Step-Down DC/DC

OUT

95% Efﬁciency, VIN: 2.5V to 5.5V, V I

< 1µA, ThinSOTTM Package

95% Efﬁciency, VIN: 2.5V to 5.5V, V I

< 1µA, 10-Lead MS or DFN Packages

= 0.6V, IQ = 20µA,

OUT(MIN)

= 0.8V, IQ = 60µA,

OUT(MIN)

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507

●

www.linear.com

3080fc

LT 0911 REV C • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2007

ANALOG DEVICES LT 3080EMS8E, LT 3080 EST Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual

FeaTures

applicaTions

DescripTion

Typical applicaTion

absoluTe MaxiMuM raTings

pin conFiguraTion

orDer inForMaTion

elecTrical characTerisTics

Typical perForMance characTerisTics

pin FuncTions

block DiagraM

applicaTions inForMaTion

Typical applicaTions

package DescripTion

revision hisTory

Typical applicaTion

relaTeD parTs