LT3085EMS8E-TR datasheet, PDF - EEWORLD Datasheet

FEATURES

n

LT3085

Adjustable 500mA Single

Resistor Low Dropout

Regulator

DESCRIPTION

The LT

®

3085 is a 500mA low dropout linear regulator that

can be paralleled to increase output current or spread

heat on surface mounted boards. Designed as a precision

current source and voltage follower, this new regulator

ﬁnds use in many applications requiring high current,

adjustability to zero, and no heat sink. The device also

brings out the collector of the pass transistor to allow

low dropout operation—down to 275mV—when used

with a second supply.

A key feature of the LT3085 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 LT3085 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 LT3085 is offered in the 8-lead

MSOP and a low proﬁle (0.75mm) 6-lead 2mm

×

3mm

DFN package (both with an Exposed Pad for better thermal

characteristics).

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.

Outputs May be Paralleled for Higher Current and

Heat Spreading

Output Current: 500mA

Single Resistor Programs Output Voltage

1% Initial Accuracy of SET Pin Current

Output Adjustable to 0V

Current Limit Constant with Temperature

Low Output Noise: 40μV

RMS

(10Hz to 100kHz)

Wide Input Voltage Range: 1.2V to 36V

Low Dropout Voltage: 275mV

< 1mV Load Regulation

< 0.001%/ V Line Regulation

Minimum Load Current: 0.5mA

Stable with Minimum 2.2μF Ceramic Capacitor

Current Limit with Foldback and Overtemperature

Protected

8-Lead MSOP, and 6-Lead 2mm

×

3mm DFN Packages

APPLICATIONS

n

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

TYPICAL APPLICATION

Variable Output Voltage 500mA Supply

V

IN

1.2V TO 36V

IN

V

CONTROL

LT3085

N = 1676

1μF

SET

+

–

OUT

V

OUT

2.2μF

9.80

10.00

10.20

9.90

10.10

SET PIN CURRENT DISTRIBUTION (μA)

3085 TA01b

R

SET

V

OUT

= R

SET

• 10μA

3085 TA01a

3085fb

1

LT3085

ABSOLUTE MAXIMUM RATINGS

(Note 1) All Voltages Relative to V

OUT

V

CONTROL

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

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

SET Pin Current (Note 7) ....................................

±15mA

SET Pin Voltage (Relative to OUT) ..........................±10V

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

Operating Junction Temperature Range (Notes 2, 10)

E, I Grade ........................................... –40°C to 125°C

MP Grade........................................... –55°C to 125°C

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

Lead Temperature (Soldering, 10 sec)

MS8E Package Only .......................................... 300°C

PIN CONFIGURATION

TOP VIEW

OUT 1

OUT 2

SET 3

7

6 IN

5 IN

4 V

CONTROL

OUT

SET

1

2

3

4

8

7

6

5

IN

NC

V

CONTROL

9

DCB PACKAGE

6-LEAD (2mm 3mm) PLASTIC DFN

T

JMAX

= 125°C,

θ

JA

= 73°C/W,

θ

JC

= 10.6°C/W

EXPOSED PAD (PIN 7) IS OUT, MUST BE SOLDERED TO V

OUT

ON PCB

SEE THE APPLICATIONS INFORMATION SECTION

MS8E PACKAGE

8-LEAD PLASTIC MSOP

T

JMAX

= 125°C,

θ

JA

= 60°C/W,

θ

JC

= 10°C/W

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

OUT

ON PCB

SEE THE APPLICATIONS INFORMATION SECTION

ORDER INFORMATION

LEAD FREE FINISH

LT3085EDCB#PBF

LT3085EMS8E#PBF

LT3085IDCB#PBF

LT3085IMS8E#PBF

LT3085MPMS8E#PBF

LEAD BASED FINISH

LT3085EDCB

LT3085EMS8E

LT3085IDCB

LT3085IMS8E

LT3085MPMS8E

TAPE AND REEL

LT3085EDCB#TRPBF

LT3085EMS8E#TRPBF

LT3085IDCB#TRPBF

LT3085IMS8E#TRPBF

LT3085MPMS8E#TRPBF

TAPE AND REEL

LT3085EDCB#TR

LT3085EMS8E#TR

LT3085IDCB#TR

LT3085IMS8E#TR

LT3085MPMS8E#TR

PART MARKING*

LDQQ

LTDQP

LDQQ

LTDQP

LTDWQ

PART MARKING*

LDQQ

LTDQP

LDQQ

LTDQP

LTDWQ

PACKAGE DESCRIPTION

6-Lead (2mm

×

3mm) Plastic DFN

8-Lead Plastic MSOP

6-Lead (2mm

×

3mm) Plastic DFN

8-Lead Plastic MSOP

PACKAGE DESCRIPTION

6-Lead (2mm

×

3mm) Plastic DFN

8-Lead Plastic MSOP

6-Lead (2mm

×

3mm) Plastic DFN

8-Lead Plastic MSOP

TEMPERATURE RANGE

–40°C to 125°C

–55°C to 125°C

TEMPERATURE RANGE

–40°C to 125°C

–55°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/

3085fb

2

LT3085

ELECTRICAL CHARACTERISTICS

PARAMETER

SET Pin Current

Output Offset Voltage (V

OUT

– V

SET

)

Load Regulation

Line Regulation

Minimum Load Current (Notes 3, 9)

V

CONTROL

Dropout Voltage (Note 4)

V

IN

Dropout Voltage (Note 4)

V

CONTROL

Pin Current (Note 5)

Current Limit (Note 9)

Error Ampliﬁer RMS Output Noise (Note 6)

Ripple Rejection

CONDITIONS

I

SET

V

IN

= 1V, V

CONTROL

= 2V, I

LOAD

= 1mA, T

J

= 25°C

V

IN

≥ 1V, V

CONTROL

≥ 2V, 1mA ≤ I

LOAD

≤ 500mA (Note 9)

V

OS

V

IN

= 1V, V

CONTROL

= 2V, I

LOAD

= 1mA, T

J

= 25°C

V

IN

= 1V, V

CONTROL

= 2V, I

LOAD

= 1mA

ΔI

SET

ΔI

LOAD

= 1mA to 500mA

ΔV

OS

ΔI

LOAD

= 1mA to 500mA (Note 8)

ΔI

SET

ΔV

IN

= 1V to 36V,

ΔV

CONTROL

= 2V to 36V, I

LOAD

= 1mA

ΔV

OS

ΔV

IN

= 1V to 36V,

ΔV

CONTROL

= 2V to 36V, I

LOAD

= 1mA

V

IN

= V

CONTROL

= 10V

V

IN

= V

CONTROL

= 36V

I

LOAD

= 100mA

I

LOAD

= 500mA

I

LOAD

= 100mA

I

LOAD

= 500mA

I

LOAD

= 100mA

I

LOAD

= 500mA

V

IN

= 5V, V

CONTROL

= 5V, V

SET

= 0V, V

OUT

= –0.1V

,

I

LOAD

= 500mA, 10Hz ≤ f ≤ 100kHz, C

OUT

= 10μF C

SET

= 0.1μF

f = 120Hz, V

RIPPLE

= 0.5V

P-P

I

LOAD

= 0.1A, C

SET

= 0.1μF C

OUT

= 2.2μF

,

f=10kHz

f=1MHz

10ms Pulse

l

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C (Note 2).

MIN

9.9

9.8

–1.5

–3

–0.1

–0.6

0.1

0.003

300

1.2

1.35

85

275

3

8

500

650

33

0.7

90

75

20

0.003

TYP

10

MAX

10.1

10.2

1.5

3

–1

0.5

500

1

1.6

150

450

6

15

UNITS

μA

mV

nA

mV

nA/V

mV/V

μA

mA

V

mV

mA

μV

RMS

nA

RMS

dB

%/W

Reference Current RMS Output Noise (Note 6) 10Hz ≤ f≤ 100kHz

Thermal Regulation, I

SET

Note 1:

Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2.

Unless otherwise speciﬁed, all voltages are with respect to V

OUT

.

The LT3085 is tested and speciﬁed under pulse load conditions such that

T

J

≅

T

A

. The LT3085E is 100% tested at T

A

= 25°C. Performance of the

LT3085E over the full –40°C to 125°C operating junction temperature

range is assured by design, characterization, and correlation with

statistical process controls. The LT3085I regulators are guaranteed

over the full –40°C to 125°C operating junction temperature range. The

LT3085 (MP grade) is 100% tested and guaranteed over the –55°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 LT3085, dropout is caused by either minimum control

voltage (V

CONTROL

) or minimum input voltage (V

IN

). Both parameters are

speciﬁed with respect to the output voltage. The speciﬁcations represent

the minimum input-to-output differential voltage required to maintain

regulation.

Note 5.

The V

CONTROL

pin current is the drive current required for the

output transistor. This current will track output current with roughly a 1:60

ratio. The minimum value is equal to the quiescent current of the device.

Note 6.

Output noise is lowered by adding a small capacitor across the

voltage setting resistor. Adding this capacitor bypasses the voltage setting

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

to error ampliﬁer noise (see Applications Information section).

Note 7.

The SET pin is clamped to the output with diodes through 1k

resistors. These resistors and diodes will only carry current under

transient overloads.

Note 8.

Load regulation is Kelvin sensed at the package.

Note 9.

Current limit includes foldback protection circuitry. Current limit

decreases at higher input-to-output differential voltages. See the Typical

Performance Characteristics graphs for more information.

Note 10.

This IC includes over-temperature protection that is intended

to protect the device during momentary overload conditions. Junction

temperature will exceed the maximum operating junction temperature

when over-temperature protection is active. Continuous operation above

the speciﬁed maximum operating junction temperature may impair device

reliability.

3085fb

3

LT3085

TYPICAL PERFORMANCE CHARACTERISTICS

Set Pin Current

10.20

10.15

SET PIN CURRENT (μA)

10.10

10.05

10.00

9.95

9.90

9.85

9.80

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3085 G01

Set Pin Current Distribution

2.0

N = 1676

OFFSET VOLTAGE (mV)

9.80

10.00

10.20

9.90

10.10

SET PIN CURRENT DISTRIBUTION (μA)

3085 G02

Offset Voltage (V

OUT

– V

SET

)

1.5

1.0

0.5

0

–0.5

–1.0

–1.5

–2.0

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3085 G03

Offset Voltage Distribution

1.00

N = 1676

OFFSET VOLTAGE (mV)

0.75

Offset Voltage

0.25

I

LOAD

= 1mA

0

Offset Voltage

T

J

= 25°C

0.25

0

–0.25

–0.50

–0.75

–1.00

–2

0

–1

1

V

OS

DISTRIBUTION (mV)

2

3085 G04

OFFSET VOLTAGE (mV)

0.50

–0.25

–0.50

T

J

= 125°C

–0.75

–1.00

–1.25

–1.50

0

6

24

30

18

INPUT-TO-OUTPUT VOLTAGE (V)

12

36

3085 G05

–1.75

0 50 100 150 200 250 300 350 400 450 500

LOAD CURRENT (mA)

3085 G06

Load Regulation

CHANGE IN OFFSET VOLTAGE WITH LOAD (mV)

0

–0.1

–0.2

–0.3

–0.4

–0.5

–0.6

–0.7

–0.8

–50 –25

CHANGE IN OFFSET VOLTAGE

0

(V

OUT

– V

SET

)

ΔI

LOAD

= 1mA TO 500mA

V

IN

– V

OUT

= 2V

CHANGE IN REFERENCE CURRENT

20

MINIMUM LOAD CURRENT (mA)

10

0

–10

–20

–30

–40

–50

CHANGE IN REFERENCE CURRENT

WITH LOAD (nA)

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

Minimum Load Current

400

V

IN, CONTROL

– V

OUT

= 36V

MINIMUM IN VOLTAGE (V

IN

– V

OUT

) (mV)

350

Dropout Voltage

(Minimum IN Voltage)

T

J

= 125°C

300

250

200

T

J

= 25°C

150

100

50

0

50 100 150 200 250 300 350 400 450 500

LOAD CURRENT (mA)

3085 G09

V

IN, CONTROL

– V

OUT

= 1.5V

–60

25 50 75 100 125 150

TEMPERATURE (°C)

3085 G07

0

–50 –25

0

25

50

75

100 125 150

3085 G08

TEMPERATURE (°C)

3085fb

4

LT3085

TYPICAL PERFORMANCE CHARACTERISTICS

Dropout Voltage

(Minimum IN Voltage)

400

MINIMUM IN VOLTAGE (V

IN

– V

OUT

) (mV)

350

I

LOAD

= 500mA

300

250

200

150

100

50

0

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3085 G10

Dropout Voltage (Minimum

V

CONTROL

Pin Voltage)

1.6

1.4

MINIMUM CONTROL VOLTAGE

(V

CONTROL

– V

OUT

) (V)

1.2

1.0

T

J

= 125°C

0.8

T

J

= 25°C

0.6

0.4

0.2

0

0 50 100 150 200 250 300 350 400 450 500

LOAD CURRENT (mA)

3085 G11

Dropout Voltage (Minimum

V

CONTROL

Pin Voltage)

1.6

1.4

MINIMUM CONTROL VOLTAGE

(V

CONTROL

– V

OUT

) (V)

1.2

1.0

0.8

0.6

0.4

0.2

0

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3085 G12

T

J

= –50°C

I

LOAD

= 500mA

I

LOAD

= 100mA

I

LOAD

= 100mA

Current Limit

700

600

CURRENT LIMIT (mA)

500

400

300

200

100

0

–50 –25

V

IN

= 7V

V

OUT

= 0V

700

600

500

400

300

Current Limit

60

OUTPUT VOLTAGE

DEVIATION (mV)

T

J

= 25°C

40

20

0

–20

–40

LOAD CURRENT

(mA)

200

100

0

200

100

0

Load Transient Response

V

OUT

= 1.5V

C

SET

= 0.1μF

V

IN

= V

CONTROL

= 3V

C

OUT

= 10μF CERAMIC

C

OUT

= 2.2μF CERAMIC

0

25 50 75 100 125 150

TEMPERATURE (°C)

3085 G13

0

5

10 15 20 25 30 35

INPUT-TO-OUTPUT DIFFERENTIAL (V)

40

0

20 40 60 80 100 120 140 160 180 200

TIME (μs)

3085 G15

3085 G14

Load Transient Response

150

OUTPUT VOLTAGE

DEVIATION (mV)

100

50

0

–50

C

OUT

= 2.2μF CERAMIC

C

OUT

= 10μF CERAMIC

OUTPUT VOLTAGE

DEVIATION (mV)

100

50

0

–50

Line Transient Response

OUTPUT VOLTAGE (V)

1.5

1

0.5

0

8

IN/CONTROL

VOLTAGE (V)

6

4

2

0

Turn-On Response

–100

6

4

2

0

LOAD CURRENT

(mA)

–100

500

250

0

0 10

V

IN

= V

CONTROL

= 3V

V

OUT

= 1.5V

C

SET

= 0.1μF

20 30 40 50 60 70 80 90 100

TIME (μs)

3085 G16

IN/CONTROL

VOLTAGE (V)

V

OUT

= 1.5V

I

LOAD

= 10mA

C

OUT

= 2.2μF

CERAMIC

C

SET

= 0.1μF

CERAMIC

C

OUT

= 2.2μF

CERAMIC

R

SET

= 100k

C

SET

= 0

R

LOAD

= 2Ω

10 20 30 40 50 60 70 80 90 100

TIME (μs)

3085 G17

0

2

4

6

8 10 12 14 16 18 20

TIME (μs)

3085 G18

3085fb

5

LT3085EMS8E-TR

LT3085EMS8E-TR Overview

Preview

Recommended Resources