ANALOG DEVICES LT 1086 IM Datasheet

FEATURES

■

3-Terminal Adjustable or Fixed

2.85V, 3.3V, 3.6V, 5V, 12V

■

Output Current of 1.5A (0.5A for LT1086H)

■

Operates Down to 1V Dropout

■

Guaranteed Dropout Voltage at Multiple Current Levels

■

Line Regulation: 0.015%

■

Load Regulation: 0.1%

■

100% Thermal Limit Functional Test

■

Ripple Rejection >75dB

■

Available in 3-Pin TO-220 and 3-Pin DD Packages

LT1086 Series

1.5A Low Dropout Positive

Regulators Adjustable and

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

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DESCRIPTIO

The LT®1086 is designed to provide up to 1.5A output
current. All internal circuitry is designed to operate down
to 1V input-to-output differential and the dropout voltage
is fully specified as a function of load current. Dropout is
guaranteed at several operating points up to a maximum
of 1.5V at maximum output current. Dropout decreases at
lower load currents. On-chip trimming adjusts the refer­ence/ouput voltage to 1%. Current limit is also trimmed,
minimizing the stress on both the regulator and power
source circuitry under overload conditions.

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APPLICATIO S

■

SCSI-2 Active Terminator

■

High Efficiency Linear Regulators

■

Post Regulators for Switching Supplies

■

Constant Current Regulators

■

Battery Chargers

■

Microprocessor Supply

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TYPICAL APPLICATIO

5V to 3.3V Regulator

V

≥ 4.75V 3.3V AT 1.5A

IN

10µF*
TANTALUM

LT1086-3.3

IN OUT

GND

LT1086 • TA01

10µF
TANTALUM

The LT1086 is pin compatible with older 3-terminal adjust­able regulators. A minimum 10µF output capacitor is
required on these devices.

The LT1086 offers excellent line and load regulation speci­fications and ripple rejection exceeds 75dB even at the
maximum load current of 1.5A. The LT1086 is floating
architecture with a composite NPN output stage. All of the
quiescent current and the drive current for the output
stage flows to the load increasing efficiency.

The LT1086 is available in a 3-pin TO-220 package and a
space-saving surface mountable 3-pin DD package.

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

LT1086 Dropout Voltage

2

INDICATES GUARANTEED TEST POINT

–55°C ≤ TJ ≤ 150°C

1

0°C ≤ T

≤ 125°C

J

T

= –55°C

J

= 25°C

T

J

= 150°C

T

J

*MAY BE OMITTED IF INPUT SUPPLY IS WELL
BYPASSED WITHIN 2" OF THE LT1086

MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)

0

0

0.5
OUTPUT CURRENT (A)

1

1.5

LT1086 • TA02

sn1086 1086ffs

1

LT1086 Series

V

IN

V

OUT

ADJ
(GND)

†

M PACKAGE

3-LEAD PLASTIC DD

FRONT VIEW

TAB IS

OUTPUT

3

2

1

WW

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

Power Dissipation............................... Internally Limited

Input Voltage* ......................................................... 30V

Operating Input Voltage

Adjustable Devices ........................................... 25V

2.85V Devices .................................................. 18V

3.3V, 3.6V, and 5V Devices ............................... 20V

12V Devices ...................................................... 25V

Operating Junction Temperature Range

“C” Grades

Control Section ............................... 0°C to 125°C

Power Transistor............................. 0°C to 150°C

“I” Grades

Control Section .......................... –40°C to 125°C

Power Transistor........................ – 40°C to 150°C

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PACKAGE/ORDER INFORMATION

BOTTOM VIEW

V

IN

3-LEAD TO-39 METAL CAN

2

13

H PACKAGE

θJA = 150°C/W

ADJ

V

OUT

(CASE)

ORDER

PART NUMBER

LT1086CH
LT1086MH

“M” Grades

Control Section .......................... –55°C to 150°C

Power Transistor........................ – 55°C to 200°C

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

Lead Temperature (Soldering, 10 sec).................. 300°C

* Although the device’s maximum operating voltage is limited, (18V for a

2.85V device, 20V for a 5V device, and 25V for adjustable and12V devices) the
devices are guaranteed to withstand transient input voltages up to 30V. For
input voltages greater than the maximum operating input voltage some
degradation of specifications will occur. For fixed voltage devices operating at
input/output voltage differentials greater than 15V, a minimum external load
of 5mA is required to maintain regulation.

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PRECONDITIONING

100% Thermal Shutdown Functional Test.

ORDER

PART NUMBER

LT1086CM
LT1086CM-3.3
LT1086CM-3.6

θJA = 30°C/W**

** WITH PACKAGE SOLDERED TO 0.5IN2 COPPER AREA

OVER BACKSIDE GROUND PLANE OR INTERNAL POWER
PLANE. θJA CAN VARY FROM 20°C/W TO >40°C/W
DEPENDING ON MOUNTING TECHNIQUE.

LT1086IM
LT1086IM-3.3

ORDER

BOTTOM VIEW

V

IN

2

CASE

IS OUTPUT

PART NUMBER

LT1086CK
LT1086CK-5
LT1086CK-12

ADJ (GND)*

1

K PACKAGE

2-LEAD TO-3 METAL CAN

θJA = 35°C/W

LT1086IK
LT1086IK-5
LT1086IK-12
LT1086MK
LT1086MK-5
LT1086MK-12

OBSOLETE PACKAGES

Consider the T Package for Alternate Source

†

For fixed versions.

Consult LTC Marketing for parts specified with wider operating temperature ranges.

2

TAB IS

OUTPUT

FRONT VIEW

3

2

1

T PACKAGE

3-LEAD PLASTIC TO-220

θJA = 50°C/W

V

IN

V

OUT

ADJ
(GND)

ORDER

PART NUMBER

LT1086CT
LT1086CT-2.85
LT1086CT-3.3
LT1086IT

†

LT1086IT-5
LT1086IT-12
LT1086CT-3.6
LT1086CT-5
LT1086CT-12

sn1086 1086ffs

LT1086 Series

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

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

PARAMETER CONDITIONS MIN TYP MAX UNITS

Reference Voltage LT1086, LT1086H I
(Note 3) 10mA ≤ I

Output Voltage LT1086-2.85 I
(Note 3) 0V ≤ I

LT1086-3.3 VIN = 5V, I

LT1086-3.6 VIN = 5V, I

LT1086-5 I

LT1086-12 I

Line Regulation LT1086, LT1086H I

LT1086-2.85 I

LT1086-3.3 4.5V ≤ VIN ≤ 18V, I

LT1086-3.6 4.75V ≤ VIN ≤ 18V, I

LT1086-5 I

LT1086-12 I

Load Regulation LT1086, LT1086H (VIN – V

LT1086-2.85 VIN = 5V, 0 ≤ I

LT1086-3.3 VIN = 5V, 0 ≤ I

LT1086-3.6 VIN = 5.25V, 0 ≤ I

LT1086-5 VIN = 8V, 0 ≤ I

LT1086-12 VIN = 15V, 0 ≤ I

Dropout Voltage LT1086/-2.85/-3.3/-3.6/-5/-12 ∆V

– V

OUT

)

(V

IN

LT1086H ∆V

= 10mA, TJ = 25°C, (VIN – V

OUT

OUT

4.75V ≤ V

5V ≤ V

4.75V ≤ V

= 4.75V, I

V

IN

OUT

0 ≤ I

OUT

0 ≤ I

LOAD

OUT

OUT

OUT

T

= 25°C (Notes 2, 3) 0.1 0.3 %

J

= 5V, 0 ≤ I

V

IN

REF

≤ 1.5A, (0.5A for LT1086H), 1.5V ≤ (VIN – V

OUT

= 0mA, TJ = 25°C, VIN = 5V 2.82 2.85 2.88 V

≤ 1.5A, 4.35V ≤ VIN ≤ 18V ● 2.79 2.85 2.91 V

OUT

= 0mA, TJ = 25°C 3.267 3.300 3.333 V

OUT

≤ 18V, 0V ≤ I

IN

= 0mA, TJ = 25°C 3.564 3.600 3.636 V

OUT

≤ 18V, 0 ≤ I

IN

≤ 18V, 0 ≤ I

IN

OUT

OUT

≤ 1.5A ● 3.500 3.672 V

OUT

OUT

= 1.5A, TJ ≥ 0°C 3.300 3.672 V

= 0mA, TJ = 25°C, VIN = 8V 4.950 5.000 5.050 V

≤ 1.5A, 6.5V ≤ VIN ≤ 20V ● 4.900 5.000 5.100 V

OUT

= 0mA, TJ = 25°C, VIN = 15V 11.880 12.000 12.120 V

≤ 1.5A, 13.5V ≤ VIN ≤ 25V ● 11.760 12.000 12.240 V

OUT

= 10mA, 1.5V ≤ (VIN – V

= 0mA, TJ = 25°C, 4.35V ≤ VIN ≤ 18V 0.3 6 mV

= 0mA, TJ = 25°C 0.5 10 mV

OUT

= 0mA, TJ = 25°C 0.5 10 mV

OUT

= 0mA, TJ = 25°C, 6.5V ≤ VIN ≤ 20V 0.5 10 mV

= 0mA, TJ = 25°C, 13.5V ≤ VIN ≤ 25V 1.0 25 mV

) = 3V, 10mA ≤ I

OUT

≤ 1.5A, TJ = 25°C (Notes 2, 3) 3 12 mV

OUT

≤ 1.5A, TJ = 25°C (Notes 2, 3) 3 15 mV

OUT

≤ 1.5A, TJ = 25°C (Notes 2, 3) 3 15 mV

OUT

≤ 1A, TJ = 25°C215mV

OUT

≤ 1.5A, TJ = 25°C (Notes 2, 3) 5 20 mV

OUT

≤ 1.5A, TJ = 25°C (Notes 2, 3) 12 36 mV

OUT

, ∆V

= 1%, I

REF

= 0.5A (Note 4) ● 0.95 1.25 V

= 1%, I

OUT

OUT

) = 3V 1.238 1.250 1.262 V

OUT

) ≤ 15V ● 1.225 1.250 1.270 V

OUT

≤ 1.5A ● 3.235 3.300 3.365 V

≤ 1A, TJ ≥ 0°C 3.500 3.672 V

) ≤ 15V, TJ = 25°C 0.015 0.2 %

OUT

≤ 1.5A, (0.5A for LT1086H)

OUT

= 1.5A (Note 4) ● 1.3 1.5 V

OUT

● 0.035 0.2 %

● 0.6 6 mV

● 1.0 10 mV

● 1.0 10 mV

● 1.0 10 mV

● 2.0 25 mV

● 0.2 0.4 %

● 620 mV

● 725 mV

● 625 mV

● 425 mV

● 10 35 mV

● 24 72 mV

sn1086 1086ffs

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LT1086 Series

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

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

PARAMETER CONDITIONS MIN TYP MAX UNITS

Current Limit LT1086/-2.85/-3.3/-3.6/-5/-12 (VIN – V

(V

IN

LT1086H (VIN – V

Minimum Load Current LT1086/LT1086H (VIN – V

(V

IN

– V

OUT

OUT

OUT

Quiescient Current LT1086-2.85 VIN ≤ 18V ● 510 mA

LT1086-3.3 V
LT1086-3.6 V
LT1086-5 V
LT1086-12 V

≤ 18V ● 510 mA

IN

≤ 18V ● 510 mA

IN

≤ 20V ● 510 mA

IN

≤ 25V ● 510 mA

IN

Thermal Regulation TA = 25°C, 30ms pulse 0.008 0.04 %/W
Ripple Rejection f = 120Hz, C

LT1086, LT1086H C
LT1086-2.85 V
LT1086-3.3 V
LT1086-3.6 V
LT1086-5 V
LT1083-12 V

= 25µF Tantalum, I

OUT

ADJ

= 6V ● 60 72 dB

IN

= 6.3V ● 60 72 dB

IN

= 6.6V ● 60 72 dB

IN

= 8V ● 60 68 dB

IN

= 15V ● 54 60 dB

IN

= 25µF, (VIN – V

Adjust Pin Current LT1086, LT1086H TJ = 25°C55µA

Adjust Pin Current LT1086, LT1086H 10mA ≤ I
Change 1.5V ≤ (V

OUT

IN

Temperature Stability ● 0.5 %
Long-Term Stability TA = 125°C, 1000 Hrs. 0.3 1 %
RMS Output Noise TA = 25°C, 10Hz = ≤ f ≤ 10kHz 0.003 %

(% of V

OUT

)

Thermal Resistance H Package: Control Circuitry/Power Transistor 15/20 °C/W
Junction-to-Case K Package: Control Circuitry/Power Transistor 1.7/4.0 °C/W

M Package: Control Circuitry/Power Transistor 1.5/4.0 °C/W
T Package: Control Circuitry/Power Transistor 1.5/4.0 °C/W

) = 5V ● 1.50 2.00 A

OUT

– V

) = 25V ● 0.05 0.15 A

OUT

) = 5V ● 0.50 0.700 A

) = 25V ● 0.02 0.075 A

) = 25V (Note 5) ● 510 mA

= 1.5A, (I

OUT

= 0.5A for LT1086H)

OUT

) = 3V ● 60 75 dB

OUT

● 120 µA

≤ 1.5A (0.5A for LT1086H)

– V

) ≤ 15V ● 0.2 5 µA

OUT

Note 1: Absolute Maximum Ratings are those values beyond which the life of
a device may be impaired.

Note 2: See Thermal Regulation specifications for changes in output
voltage due to heating effects. Line and load regulation are measured at a
constant junction temperature by low duty cycle pulse testing. Load
regulation is measured at the output lead ≈1/8" from the package.

Note 3: Line and load regulation are guaranteed up to the maximum power
dissipation of 15W (3W for the LT1086H). Power dissipation is determined

4

by the input/output differential and the output current. Guaranteed
maximum power dissipation will not be available over the full input/output
range. See Short-Circuit Current curve for available output current.

Note 4: Dropout voltage is specified over the full output current range of
the device. Test points and limits are shown on the Dropout Voltage curve.

Note 5: Minimum load current is defined as the minimum output current
required to maintain regulation. At 25V input/output differential the device
is guaranteed to regulate if the output current is greater than 10mA.

sn1086 1086ffs

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INPUT/OUTPUT DIFFERENTIAL (V)

0

0

MINIMUM OPERATING CURRENT (mA)

1

3

4

5

10

7

10

20

25

LT1086 • TPC03

2

8

9

6

5

15

30

35

TJ = 150°C

T

J

= 25°C

T

J

= –55°C

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1086 Short-Circuit Current

2.5

2.0

1.5

1.0

SHORT-CIRCUIT CURRENT (A)

0.5

0

0

TJ = 150°C

GUARANTEED

OUTPUT CURRENT

10 15 20

5

INPUT/OUTPUT DIFFERENTIAL (V)

Temperature Stability

2

1

0

–1

OUTPUT VOLTAGE CHANGE (%)

–2

–25

–50

0

50

25

TEMPERATURE (°C)

TJ = 25°C
T

= –55°C

J

75

25 30

LT1086 • TPC01

100

LT1086 • TPC04

125

150

0.10

∆I = 1.5A

0.05

0

–0.05

–0.10

–0.15

OUTPUT VOLTAGE DEVIATION (%)

–0.20

–50

050

–25 25

TEMPERATURE (°C)

Adjust Pin Current

100

90
80
70
60
50
40
30

ADJUST PIN CURRENT (µA)

20
10

0

–50

–25 25

0

50

TEMPERATURE (°C)

100

75

LT1086 • TPC02

125

100

75

LT1086 • TPC05

125

150

150

LT1086 Series

Minimum Operating Current
(Adjustable Device)LT1086 Load Regulation

LT1086 Maximum Power
Dissipation*

20

15

10

POWER (W)

5

0

60

50

*AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE

LT1086MK

LT1086CT

LT1086CK

70

80

CASE TEMPERATURE (°C)

110

100

90

120

130

LT1086 • TPC06

140

150

100

V

90
80
70

60
50
40
30

RIPPLE REJECTION (dB)

20
10

0

10 1k 10k 100k

RIPPLE

– V

(V

IN

OUT

C

= 200µF AT FREQUENCIES < 60Hz

ADJ

= 25µF AT FREQUENCIES > 60Hz

C

ADJ

= 1.5A

I

OUT

100

≤ 3V

P-P

(VIN – V

) ≥ V

DROPOUT

FREQUENCY (Hz)

V

RIPPLE

≤ 0.5V

OUT

LT1086 • TPC07

) ≥ 3V

P-P

LT1086 Ripple Rejection
vs CurrentLT1086 Ripple Rejection LT1086-5 Ripple Rejection

100

90
80
70

60

50
40

30

RIPPLE REJECTION (dB)

V

20

10

= 5V

OUT

= 25µF

C

ADJ

= 25µF

C

OUT

0

0

0.25

0.5

OUTPUT CURRENT (A)

fR = 120Hz

≤ 3V

V

RIPPLE

fR = 20kHz

≤ 0.5V

V

RIPPLE

0.75 1.0

P-P

P-P

1.25

LT1086 • TPC08

1.5

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

10

0

10 1k 10k 100k

(V

I

OUT

– V

IN

= 1.5A

V

≤ 3V

RIPPLE

) ≥ V

OUT

DROPOUT

100

FREQUENCY (Hz)

P-P

(VIN – V

V

RIPPLE

OUT

) ≥ 3V

≤ 0.5V

P-P

LT1086 • TPC09

sn1086 1086ffs

5

LT1086 Series

INPUT/OUTPUT DIFFERENTIAL (V)

0

0

SHORT-CIRCUIT CURRENT (A)

0.2

0.4

0.6

0.8

1.0

1.2

5101520

LT1086 • TPC15

25

GUARANTEED

OUTPUT CURRENT

W

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1086-5 Ripple Rejection
vs Current

100

90
80
70

60

40

RIPPLE REJECTION (dB)

fR = 120Hz

≤ 3V

V

RIPPLE

fR = 20kHz
V

50

30

20

10

RIPPLE

V

= 5V

OUT

= 25µF

C

ADJ

= 25µF

C

OUT

0

0

0.25

P-P

≤ 0.5V

P-P

0.75 1.0

0.5

OUTPUT CURRENT (A)

LT1086 Line Transient Response

60

40

20

0

–20

DEVIATION (mV)

OUTPUT VOLTAGE

–40

V

OUT

I

OUT

–60

C

IN

C

OUT

14

13

12

DEVIATION (V)

11

INPUT VOLTAGE

0

C

= 1µF

ADJ

= 10V

= 0.2A

= 1µF TANTALUM

= 10µF TANTALUM

TIME (µs)

100

LT1086-12 Ripple Rejection

LT1086-12 Ripple Rejection

1.25

LT1086 • TPC10

1.5

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

10

0

10 1k 10k 100k

I

(V

OUT

– V

IN

= 1.5A

V

≤ 3V

RIPPLE

) ≥ V

OUT

DROPOUT

100

FREQUENCY (Hz)

P-P

(VIN – V

V

RIPPLE

OUT

≤ 0.5V

) ≥ 3V

LT1086 • TPC11

P-P

LT1086 Load Transient Response

0.3

0.2

0.1
0

C

= 0

ADJ

200

LT1086 • TPC13

–0.1

DEVIATION (V)

OUTPUT VOLTAGE

–0.2
–0.3

1.5

1.0

0.5
0

LOAD CURRENT (A)

0

C

ADJ

CIN = 1µF TANTALUM

= 10µF TANTALUM

C

OUT

= 1µF

50

TIME (µs)

C

= 0

ADJ

V

= 10V

OUT

= 13V

V

IN

PRELOAD = 100mA

LT1086 • TPC14

100

vs Current

100

90
80

fR = 120Hz

≤ 3V

V

70
60

50
40
30

RIPPLE REJECTION (dB)

20
10

0

0

RIPPLE

fR = 20kHz
V

RIPPLE

V

= 5V

OUT

= 25µF

C

ADJ

= 25µF

C

OUT

0.25
OUTPUT CURRENT (A)

≤ 0.5V

0.5

P-P

P-P

0.75 1.0

LT1086H Short-Circuit Current

1.25

LT1086 • TPC12

1.5

LT1086H Dropout Voltage

2

1

MINIMUM INPUT/OUTPUT DIFFERENTIAL (V)

0

0

6

INDICATES GUARANTEED TEST POINT

–55°C ≤ TJ ≤ 150°C

0.1
OUTPUT CURRENT (A)

0°C ≤ T

0.2

≤ 125°C

J

TJ = –55°C

= 25°C

T

J

= 150°C

T

J

0.3

0.4

LT1086 • TPC16

LT1086H Load Regulation

0.10

∆I = 0.5A

0.05

0

–0.05

–0.10

–0.15

OUTPUT VOLTAGE DEVIATION (%)

–0.20

–50

0.5

–25 25

050

TEMPERATURE (°C)

75

100

125

LT1086 • TPC17

100

RIPPLE REJECTION (dB)

150

LT1086H Ripple Rejection
vs Current

90

fR = 120Hz

80
70
60

50
40
30

V

20

C

10

C

0

0

≤ 3V

V

RIPPLE

fR = 20kHz

≤ 0.5V

V

RIPPLE

= 5V

OUT

= 25µF

ADJ

= 25µF

OUT

0.1
OUTPUT CURRENT (A)

0.2

P-P

P-P

0.3 0.4

0.5

LT1086 • TPC18

sn1086 1086ffs

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U

TYPICAL PERFORMANCE CHARACTERISTICS

100

V

≤ 3V

90
80
70

60
50
40
30

RIPPLE REJECTION (dB)

20
10

0

10 1k 10k 100k

RIPPLE

– V

) ≥ V

IN

OUT

= 200µF AT FREQUENCIES < 60Hz
= 25µF AT FREQUENCIES > 60Hz

= 0.5A

100

FREQUENCY (Hz)

C
C
I

(V

ADJ
ADJ

OUT

P-P

DROPOUT

V

RIPPLE

(VIN – V

OUT

≤ 0.5V

) ≥ 3V

LT1086 • TPC19

P-P

5

4

3

2

POWER (W)

1

0

50

*AS LIMITED BY MAXIMUM JUNCTION TEMPERATURE

LT1086 Series

LT1086H Maximum Power
Dissipation*LT1086H Ripple Rejection

LT1086MH

60

70

CASE TEMPERATURE (°C)

100

110

80

90

120

130

LT1086 • TPC20

140

150

BLOCK DIAGRAM

W

V

ADJ

THERMAL

LIMIT

V

IN

+

–

1086 • BD

V

OUT

sn1086 1086ffs

7

LT1086 Series

U

WUU

APPLICATIONS INFORMATION

The LT1086 family of 3-terminal regulators is easy to use
and has all the protection features that are expected in high
performance voltage regulators. They are short-circuit
protected and have safe area protection as well as thermal
shutdown to turn off the regulator should the temperature
exceed about 165°C at the sense point.

These regulators are pin compatible with older 3-terminal
adjustable devices, offer lower dropout voltage and more
precise reference tolerance. Further, the reference stabil­ity with temperature is improved over older types of
regulators. The only circuit difference between using the
LT1086 family and older regulators is that they require an
output capacitor for stability.

Stability

The circuit design used in the LT1086 family requires the
use of an output capacitor as part of the device frequency
compensation. For all operating conditions, the addition of
150µF aluminum electrolytic or a 22µF solid tantalum on
the output will ensure stability. Normally capacitors much
smaller than this can be used with the LT1086. Many
different types of capacitors with widely varying charac­teristics are available. These capacitors differ in capacitor
tolerance (sometimes ranging up to ±100%), equivalent
series resistance, and capacitance temperature coeffi­cient. The 150µF or 22µF values given will ensure stability.

When using the LT1086 the adjustment terminal can be
bypassed to improve ripple rejection. When the adjust­ment terminal is bypassed the requirement for an output
capacitor increases. The values of 22µF tantalum or 150µF
aluminum cover all cases of bypassing the adjustment
terminal. For fixed voltage devices or adjustable devices
without an adjust pin bypass capacitor, smaller output
capacitors can be used with equally good results. The table
below shows approximately what size capacitors are needed
to ensure stability.

Recommended Capacitor Values

INPUT OUTPUT ADJUSTMENT

10µF10µF Tantalum, 50µF Aluminum None
10µF22µF Tantalum, 150µF Aluminum 20µF

Normally, capacitor values on the order of 100µF are used
in the output of many regulators to ensure good transient

response with heavy load current changes. Output capaci­tance can be increased without limit and larger values of
output capacitor further improve stability and transient
response of the LT1086 regulators.

Another possible stability problem that can occur in mono­lithic IC regulators is current limit oscillations. These can
occur because in current limit, the safe area protection
exhibits a negative impedance. The safe area protection
decreases the current limit as the input-to-output voltage
increases.That is the equivalent of having a negitive resis­tance since increasing voltage causes current to decrease.
Negative resistance during current limit is not unique to
the LT1086 series and has been present on all power IC
regulators. The value of negative resistance is a function of
how fast the current limit is folded back as input-to-output
voltage increases. This negative resistance can react with
capacitors or inductors on the input to cause oscillation
during current limiting. Depending on the value of series
resistance, the overall circuitry may end up unstable. Since
this is a system problem, it is not necessarily easy to solve;
however, it does not cause any problems with the IC
regulator and can usually be ignored.

Protection Diodes

In normal operation the LT1086 family does not need any
protection diodes. Older adjustable regulators required
protection diodes between the adjustment pin and the
output and from the output to the input to prevent over­stressing the die. The internal current paths on the LT1086
adjustment pin are limited by internal resistors. Therefore,
even with capacitors on the adjustment pin, no protection
diode is needed to ensure device safety under short-circuit
conditions.

Diodes between input and output are usually not needed.
The internal diode between the input and the output pins
of the LT1086 family can handle microsecond surge
currents of 10A to 20A. Even with large output capaci­tances, it is very difficult to get those values of surge
currents in normal operation. Only with high value output
capacitors such as 1000µF to 5000µF, and with the input
pin instantaneously shorted to ground, can damage occur.
A crowbar circuit at the input of the LT1086 can generate
those kinds of currents and a diode from output to input is
then recommended. Normal power supply cycling or even

sn1086 1086ffs

8

LT1086 Series

U

WUU

APPLICATIONS INFORMATION

plugging and unplugging in the system will not generate
current large enough to do any damage.

The adjustment pin can be driven on a transient basis
±25V, with respect to the output without any device
degradation. Of course as with any IC regulator, exceeding
the maximum input-to-output voltage differential causes
the internal transistors to break down and none of the
protection circuitry is functional.

D1

1N4002

(OPTIONAL)

VIN V

LT1086

IN OUT

ADJ

+

C

ADJ

10µF

C

OUT

150µF

LT1086 • AI01

OUT

+

R1

R2

Overload Recovery

Like any of the IC power regulators, the LT1086 has safe
area protection. The safe area protection decreases the
current limit as input-to-output voltage increases and
keeps the power transistor inside a safe operating region
for all values of input-to-output voltage. The LT1086
protection is designed to provide some output current at
all values of input-to-output voltage up to the device
breakdown.

When power is first turned on, as the input voltage rises,
the output follows the input, allowing the regulator to start
up into very heavy loads. During the start-up, as the input
voltage is rising, the input-to-output voltage differential
remains small, allowing the regulator to supply large
output currents. With high input voltage, a problem can
occur wherein removal of an output short will not allow the
output voltage to recover. Older regulators such as the
7800 series also exhibited this phenomenon, so it is not
unique to the LT1086.

the power supply may need to be cycled down to zero and
brought up again to make the output recover.

Ripple Rejection

For the LT1086 the typical curves for ripple rejection
reflect values for a bypassed adjust pin. This curve will be
true for all values of output voltage. For proper bypassing
and ripple rejection approaching the values shown, the
impedance of the adjust pin capacitor at the ripple fre­quency should equal the value of R1, (normally 100Ω to
120Ω). The size of the required adjust pin capacitor is a
function of the input ripple frequency. At 120Hz the adjust
pin capacitor should be 13µF if R1 = 100Ω; at 10kHz only

0.16µF is needed.
For circuits without an adjust pin bypass capacitor the

ripple rejection will be a function of output voltage. The
output ripple will increase directly as a ratio of the output
voltage to the reference voltage (V
ample, with the output voltage equal to 5V and no adjust
pin capacitor, the output ripple will be higher by the ratio
of 5V/1.25V or four times larger. Ripple rejection will be
degraded by 12dB from the value shown on the LT1086
curve. Typical curves are provided for the 5V and 12V
devices since the adjust pin is not available.

Output Voltage

The LT1086 develops a 1.25V reference voltage between
the output and the adjust terminal (see Figure 1). By
placing resistor R1 between these two terminals, a con­stant current is caused to flow through R1 and down
through R2 to set the overall output voltage. Normally this
current is chosen to be the specified minimum load
current of 10mA. Because I
when compared with the current through R1, it repre­sents a small error and can usually be ignored. For fixed
voltage devices R1 and R2 are included in the device.

OUT/VREF

is very small and constant

ADJ

). For ex-

The problem occurs with a heavy output load when the
input voltage is high and the output voltage is low, such as
immediately after a removal of a short. The load line for
such a load may intersect the output current curve at two
points. If this happens there are two stable output operat­ing points for the regulator. With this double intersection

LT1086

V

IN

IN OUT

ADJ

I

ADJ

50µA

V

= V

OUT

Figure 1. Basic Adjustable Regulator

R2

1 + + I

REF

( )

R1

ADJ

R2

V

R1

REF

R2

+

10µF
TANTALUM

V

OUT

1086 • F01

sn1086 1086ffs

9

LT1086 Series

U

WUU

APPLICATIONS INFORMATION

Load Regulation

Because the LT1086 is a 3-terminal device, it is not
possible to provide true remote load sensing. Load regu­lation will be limited by the resistance of the wire connect­ing the regulator to the load. The data sheet specification
for load regulation is measured at the bottom of the
package. Negative side sensing is a true Kelvin connec­tion, with the bottom of the output divider returned to the
negative side of the load. Although it may not be immedi­ately obvious, best load regulation is obtained when the
top of the resistor divider R1 is connected
case

not to the load

, as illustrated in Figure 2. If R1 were
connected to the load, the effective resistance between the
regulator and the load would be:

R2 + R1

RP , RP = Parasitic Line Resistance

()

R1

R

P

PARASITIC

IN

Figure 2. Connections for Best Load Regulation

LT1086 OUTINV

ADJ

*CONNECT R1 TO CASE
CONNECT R2 TO LOAD

LINE RESISTANCE

R1*

R2*

Connected as shown, RP is not multiplied by the divider
ratio. RP is about 0.004Ω per foot using 16-gauge wire.
This translates to 4mV/ft at 1A load current, so it is
important to keep the positive lead between regulator and
load as short as possible and use large wire or PC board
traces.

Note that the resistance of the package leads for the H
package ≈0.06Ω/inch. While it is usually not possible to
connect the load directly to the package, it is possible to
connect larger wire or PC traces close to the case to avoid
voltage drops that will degrade load regulation.

For fixed voltage devices the top of R1 is internally Kelvin
connected and the ground pin can be used for negative
side sensing.

directly

R

L

1086 • F02

to the

Thermal Considerations

The LT1086 series of regulators have internal power and
thermal limiting circuitry designed to protect the device
under overload conditions. For continuous normal load
conditions however, maximum junction temperature rat­ings must not be exceeded. It is important to give careful
consideration to all sources of thermal resistance from
junction to ambient. This includes junction-to-case, case­to-heat sink interface and heat sink resistance itself. New
thermal resistance specifications have been developed to
more accurately reflect device temperature and ensure
safe operating temperatures. The data section for these
new regulators provides a separate thermal resistance and
maximum junction temperature for both the

tion

and the

Power Transistor

. Previous regulators, with a

Control Sec-

single junction-to-case thermal resistance specification,
used an average of the two values provided here and
therefore could allow excessive junction temperatures
under certain conditions of ambient temperature and heat
sink resistance. To avoid this possibility, calculations
should be made for both sections to ensure that both
thermal limits are met.

For example, using a LT1086CK (TO-3, Commercial) and
assuming:

VIN(max continuous) = 9V, V
TA = 75°C, θ

θ

CASE-TO-HEAT SINK

HEAT SINK

= 3°C/W,

= 0.2°C/W for T package with

OUT

= 5V, I

OUT

= 1A,

thermal compound.

Power dissipation under these conditions is equal to:

PD = (VIN – V

OUT

)(I

OUT

) = 4W

Junction temperature will be equal to:

TJ = TA + PD (θ

HEAT SINK

+ θ

CASE-TO-HEAT SINK

+ θJC)

For the Control Section:

TJ = 75°C + 4W(3°C/W + 0.2°C/W + 1.5°C/W) = 94.6°C
95°C < 125°C = T

(Control Section

JMAX

Commercial Range)

For the Power Transistor:

TJ = 75°C + 4W(3°C/W + 0.2°C/W + 4°C/ W) = 103.8°C

103.8°C < 150°C = T

(Power Transistor

JMAX

Commercial Range)

sn1086 1086ffs

10

LT1086 Series

U

WUU

APPLICATIONS INFORMATION

In both cases the junction temperature is below the
maximum rating for the respective sections, ensuring
reliable operation.

Junction-to-case thermal resistance for the K and T pack­ages 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. While this is also the lowest resistance
path for the H package, most available heat sinks for this
package are of the clip-on type that attach to the cap of the
package. The data sheet specification for thermal resis­tance for the H package is therefore written to reflect this.

U

TYPICAL APPLICATIONS

5V, 1.5A Regulator

In all cases proper mounting is required to ensure the best
possible heat flow from the die to the heat sink. Thermal
compound at the case-to-heat sink interface is strongly
recommended. In the case of the H package, mounting the
device so that heat can flow out the bottom of the case will
significantly lower thermal resistance (≈ a factor of 2). If
the case of the device must be electrically isolated, a
thermally conductive spacer can be used as long as its
added contribution to thermal resistance is considered.
Note that the case of all devices in this series is electrically
connected to the output.

1N5817

4.25V
TO 5.25V

V

≥ 6.5V 5V AT 1.5A

IN

+

*REQUIRED FOR STABILITY

IN OUT

10µF

LT1086

ADJ

121Ω
1%

365Ω
1%

+

SCSI-2 Active Termination

TERMPWR

LT1086-2.85IN OUT

+ +

10µF
TANTALUM

GND

10µF
TANTALUM

0.1µF
CERAMIC

18 TOTAL

10µF*
TANTALUM

LT1086 • AI02

110Ω

110Ω

110Ω

2%

2%

2%

110Ω

110Ω

110Ω

LT1086 • TA03

sn1086 1086ffs

11

LT1086 Series

TYPICAL APPLICATIONS

U

1.2V to 15V Adjustable Regulator

V

IN

*NEEDED IF DEVICE IS FAR FROM FILTER CAPACITORS

†

V

OUT

+

C1*
10µF

= 1.25V 1 +

IN OUT

LT1086

ADJ

R2
5k

R2

(

)

R1

R1
121Ω

Battery Charger

I

F

R

LT1086

IN

V

IN

– 1.25

OUT

I

=

F

dI

F

=

()

dV

OUT

R2

1 +V

()

R1

R2

1 + – R

S

()

R1

1

R2

1 + – R

S

()

R1

ADJ

1.25V

R2

OUT

S

R1

LT1086 • TA06

5V Regulator with Shutdown

†

V

OUT

+

C2
100µF

LT1086 • TA04

V

TTL

IN

IN

+

10µF

1k

1k

LT1086

ADJ

2N3904

OUT

121Ω
1%

365Ω
1%

LT1086 • TA05

5V

+

100µF

Adjusting Output Voltage of Fixed Regulators

V

OUT

> 12V 5V TO 10V

V

IN

+ +

10µF

LT1086-5

IN OUT

GND

100µF

+

10µF*

*OPTIONAL IMPROVES RIPPLE REJECTION

1k

LT1086 • TA07

Regulator with Reference Protected High Current Lamp Driver

V

> 11.5V 10V

IN

IN OUT

10µF

V

IN

LT1086-5

GND

++

5V

LT1029

LT1086 OUTIN

ADJ

+

10µF

RETURN

100µF

LT1086 • TA08

Remote Sensing

(MAX DROP 300mV)

+

100µF

25Ω

121Ω

365Ω

6

R

V

1

100pF

TTL OR

CMOS

P

IN

7

LM301A

8

LT1086

10k

2

–

1k

3

+

5µF

4

R

L

ADJ

V
5V

INOUT

OUT

15V

12V

1A

LT1086 • TA10

+

25Ω

RETURN

LT1086 • TA09

sn1086 1086ffs

12

U

TYPICAL APPLICATIONS

HEAT SINK

DARLINGTON

MDA201

2N6667

+

–

Q1

10k

+

4700µF

MBR360

High Efficiency Dual Linear Supply

L1

285µH

1000µF

++

1k

510k

8

7

LT1011

4

2.4k

2

+

3

–

IN OUT

30k

LT1086

ADJ

LT1004-2.5

20k*

30.1k*

LT1086 Series

12V

124Ω*

+

100µF

1.07k*

1.5A

D1
1N4002

130VAC

TO 90VAC

STANCOR
P-8685

DARLINGTON

HEAT SINK

2N6667

Q2

+

MDA201

+

–

*1% FILM RESISTORS
MDA = MOTOROLA
L1 = PULSE ENGINEERING, INC. #PE-92106

MBR360

10k

4700µF

FEEDBACK PATH

L1

285µH

1000µF

1k

510k

8

7

LT1011

4

2.4k

30k

2

+

3

–

High Efficiency Dual Supply

MUR410

5V OUTPUT
(TYPICAL)

+

470µF

LT1086

IN OUT

ADJ

LT1004-2.5

20k*

30.1k*

124Ω*

1.07k*

+

100µF

LT1086 • TA11

D2
1N4002

–12V

1.5A

V

IN

SWITCHING

REGULATOR

*1% FILM RESISTORS

MUR410

MUR410

IN OUT

+

470µF

IN OUT

+

470µF

LT1086

ADJ

+

LT1086

ADJ

+

10µF

10µF

124Ω*

1.07k*

124Ω*

1.07k*

12V

1.5A

+

10µF

+

10µF

LT1086 • TA12

1N4002

1N4002

–12V

1.5A

sn1086 1086ffs

13

LT1086 Series

R1
121Ω
1%

IN OUT

ADJ

R2
365Ω
1%

10µF

V

IN

≥ 6.5V

LT1086

V

OUT

= 5V

LT1086 • TA14

+

C1
10µF*

150µF

+

*C1 IMPROVES RIPPLE REJECTION.
XC SHOULD BE ≈ R1 AT RIPPLE FREQUENCY

TYPICAL APPLICATIONS

U

V

IN

Battery Backed Up Regulated Supply

IN OUT

+

SELECT FOR
CHARGE RATE

+

10µF

10µF6.5V

LT1086-5

GND

IN OUT

LT1086-5

GND

Automatic Light Control Low Dropout Negative Supply

V

IN

IN

+

10µF

LT1086

ADJ

OUT

50Ω

1.2k

+

5.2V LINE
5V BATTERY

100µF

LT1086 • TA13

100µF

LT1086 • TA15

V

IN

FLOATING INPUT

Improving Ripple Rejection

LT1086-12

IN

+ +

10,000µF

GND

OUT

LT1086 • TA16

100µF

V

OUT

= –12V

PACKAGE DESCRIPTION

REFERENCE

PLANE

0.016 – 0.021**
(0.406 – 0.533)

14

(1.270)

DIA

0.050

MAX

0.350 – 0.370

(8.890 – 9.398)

0.305 – 0.335

(7.747 – 8.509)

U

0.165 – 0.185

(4.191 – 4.699)

*

(12.700)

H Package

3-Lead TO-39 Metal Can

(Reference LTC DWG # 05-08-1330)

0.029 – 0.045

(0.737 – 1.143)

0.028 – 0.034

(0.711 – 0.864)

0.500

MIN

*

LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE
AND 0.045" BELOW THE REFERENCE PLANE

**

FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS

OBSOLETE PACKAGE

PIN 1

0.200

(5.080)

TYP

0.100

(2.540)

0.100

(2.540)

45°

H3(TO-39) 1098

0.016 – 0.024

(0.406 – 0.610)

sn1086 1086ffs

PACKAGE DESCRIPTION

0.320 – 0.350
(8.13 – 8.89)

0.420 – 0.480

(10.67 – 12.19)

0.210 – 0.220
(5.33 – 5.59)

LT1086 Series

U

K Package

2-Lead TO-3 Metal Can

(Reference LTC DWG # 05-08-1310)

0.760 – 0.775

(19.30 – 19.69)

0.060 – 0.135

(1.524 – 3.429)

0.038 – 0.043

(0.965 – 1.09)

1.177 – 1.197

(29.90 – 30.40)

0.655 – 0.675

(16.64 – 17.15)

0.151 – 0.161
(3.86 – 4.09)

DIA, 2PLCS

0.256

(6.502)

0.060

(1.524)

0.300

(7.620)

BOTTOM VIEW OF DD PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

(1.524)

(1.905)

0.060

0.075

0.183

(4.648)

0.425 – 0.435

(10.80 – 11.05)

0.060

(1.524)

TYP

0.330 – 0.370

(8.382 – 9.398)

0.143

3.632

()

0.067 – 0.077
(1.70 – 1.96)

0.490 – 0.510

(12.45 – 12.95)

R

OBSOLETE PACKAGE

M Package

3-Lead Plastic DD Pak

(Reference LTC DWG # 05-08-1460)

0.390 – 0.415

(9.906 – 10.541)

+0.012
–0.020

+0.305
–0.508

(1.270)

0.090 – 0.110

(2.286 – 2.794)

0.050

BSC

0.167 – 0.177
(4.24 – 4.49)

R

15

° TYP

K2 (TO-3) 1098

(4.191 – 4.572)

0.165 – 0.180

0.059

(1.499)

TYP

0.013 – 0.023

(0.330 – 0.584)

0.045 – 0.055

(1.143 – 1.397)

+0.008

0.004
–0.004

+0.203

0.102

()

–0.102

0.095 – 0.115

(2.413 – 2.921)

± 0.012

0.050

(1.270 ± 0.305)

M (DD3) 1098

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.

sn1086 1086ffs

15

LT1086 Series

PACKAGE DESCRIPTION

0.390 – 0.415

(9.906 – 10.541)

0.460 – 0.500

(11.684 – 12.700)

0.980 – 1.070

(24.892 – 27.178)

0.520 – 0.570

(13.208 – 14.478)

U

T Package

3-Lead Plastic TO-220

(Reference LTC DWG # 05-08-1420)

0.147 – 0.155

(3.734 – 3.937)

DIA

0.230 – 0.270

(5.842 – 6.858)

0.570 – 0.620

(14.478 – 15.748)

0.330 – 0.370

(8.382 – 9.398)

0.218 – 0.252

(5.537 – 6.401)

0.165 – 0.180

(4.191 – 4.572)

0.045 – 0.055

(1.143 – 1.397)

0.100

(2.540)

BSC

0.028 – 0.038

(0.711 – 0.965)

0.050

(1.270)

TYP

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LT1129 700mA, Micropower, LDO VIN = 4.2V to 30V, V

DD, SOT-223, S8, TO-220, TSSOP-20 Packages

LT1528 3A LDO for Microprocessor Applications VIN = 4V to 15V, V

Fast Transient Response, DD, TO-220 Packages

LT1585 4.6A LDO , with Fast Transient Response VIN = 2.5V to 7V, V

Fast Transient Response, DD, TO-220 Packages

LT1761 100mA, Low Noise Micropower, LDO VIN = 1.8V to 20V, V

Low Noise < 20µV

LT1762 150mA, Low Noise Micropower, LDO VIN = 1.8V to 20V, V

Low Noise < 20µV

LT1763 500mA, Low Noise Micropower, LDO VIN = 1.8V to 20V, V

Low Noise < 20µV

LT1764/LT1764A 3A, Low Noise, Fast Transient Response, LDOs VIN = 2.7V to 20V, V

< 40µV

RMS P-P

LT1962 300mA, Low Noise Micropower, LDO VIN = 1.8V to 20V, V

Low Noise < 20µV

LT1963/LT1963A 1.5A, Low Noise, Fast Transient Response, LDOs VIN = 2.1V to 20V, V

Low Noise < 40µV
DD, TO-220, SOT-223, S8 Packages

LT1964 200mA, Low Noise Micropower, Negative LDO VIN = –0.9V to –20V, V

Low Noise < 30µV

ThinSOT is a trademark of Linear Technology Corporation.

Linear T echnology Corporation

16

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

OUT(MIN)

OUT(MIN)

RMS P-P

RMS P-P

RMS P-P

, “A” Version Stable with Ceramic Capacitor, DD, TO-220 Packages

RMS P-P

RMS P-P

RMS P-P

0.013 – 0.023

(0.330 – 0.584)

= 3.75V, IQ = 50µA, ISD = 16µA,

OUT(MIN)

0.095 – 0.115

(2.413 – 2.921)

T3 (TO-220) 1098

= 3.30V, IQ = 400µA, ISD = 125µA,

= 1.25V, IQ = 8mA,

= 1.22V, IQ = 20µA, ISD = <1µA,

OUT(MIN)

, Stable with 1µF Ceramic Capacitors, ThinSOTTM Package

= 1.22V, IQ = 25µA, ISD = <1µA,

OUT(MIN)

, MSOP Package

= 1.22V, IQ = 30µA, ISD = <1µA,

OUT(MIN)

, S8 Package

= 1.21V, IQ = 1mA, ISD = <1µA, Low Noise

OUT(MIN)

= 1.22V, IQ = 30µA, ISD = <1µA,

OUT(MIN)

, MS8 Package

= 1.21V, IQ = 1mA, ISD = <1µA,

OUT(MIN)

,“A” Version Stable with Ceramic Capacitor,

= –1.21V, IQ = 30µA, ISD = 3µA,

OUT(MIN)

, Stable with Ceramic Capacitors, ThinSOT Package

LT/TP 0703 1K REV F • PRINTED IN USA

© LINEAR TECHNOLOGY CORPORATION 1988

sn1086 1086ffs