LT1963AES8-3.3TRPBF_技术文档

LT1963A Series

1.5A, Low Noise,

Fast Transient Response

LDO Regulators

FEATURES

DESCRIPTION

TheLT^®1963Aseriesarelowdropoutregulatorsoptimized

for fast transient response. The devices are capable of

supplying 1.5A of output current with a dropout voltage of

340mV. Operating quiescent current is 1mA, dropping to

<1μA in shutdown. Quiescent current is well controlled; it

does not rise in dropout as it does with many other regula-

tors. In addition to fast transient response, the LT1963A

regulators have very low output noise which makes them

ideal for sensitive RF supply applications.

n

Optimized for Fast Transient Response

n

Output Current: 1.5A

n

Dropout Voltage: 340mV

n

Low Noise: 40μV

(10Hz to 100kHz)

RMS

n

1mA Quiescent Current

No Protection Diodes Needed

Controlled Quiescent Current in Dropout

Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V

Adjustable Output from 1.21V to 20V

<1μA Quiescent Current in Shutdown

Stable with 10μF Output Capacitor*

Stable with Ceramic Capacitors*

Reverse Battery Protection

Output voltage range is from 1.21V to 20V. The LT1963A

regulators are stable with output capacitors as low as

10μF.Internalprotectioncircuitryincludesreversebattery

protection, current limiting, thermal limiting and reverse

currentprotection.Thedevicesareavailableinﬁxedoutput

voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an adjustable

devicewitha1.21Vreferencevoltage.TheLT1963Aregula-

tors are available in 5-lead TO-220, DD, 3-lead SOT-223,

8-lead SO and 16-lead TSSOP packages.

No Reverse Current

Thermal Limiting

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

8-Lead SO Packages

APPLICATIONS

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

All other trademarks are the property of their respective owners. Protected by U.S. Patents,

including 6118263, 6144250.

n

3.3V to 2.5V Logic Power Supplies

n

*See Applications Information Section.

Post Regulator for Switching Supplies

TYPICAL APPLICATION

Dropout Voltage

400

3.3V to 2.5V Regulator

350

300

250

200

150

100

50

2.5V

1.5A

IN

OUT

+

V

> 3V

10μF*

IN

LT1963A-2.5

SHDN SENSE

GND

*TANTALUM,

CERAMIC OR

ALUMINUM ELECTROLYTIC

1963A TA01

0

0.8 1.0

0

0.2 0.4 0.6

1.2 1.4 1.6

OUTPUT CURRENT (A)

1963A TA02

1963afd

1

LT1963A Series

ABSOLUTE MAXIMUM RATINGS

(Note 1)

Operating Junction Temperature Range (Note 3)

IN Pin Voltage ........................................................ ±20V

OUT Pin Voltage......................................................±20V

Input to Output Differential Voltage (Note 2)...........±20V

SENSE Pin Voltage ............................................... ±20V

ADJ Pin Voltage ...................................................... ±±V

SHDN Pin Voltage ................................................. ±20V

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

LT1963AE...........................................–40°C to 125°C

LT1963AI............................................–40°C to 125°C

LT1963AMP .......................................–55°C to 125°C

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

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

PIN CONFIGURATION

TOP VIEW

GND

NC

1

2

3

4

5

6

±

8

16

15

14

13

12

11

10

9

GND

NC

FRONT VIEW

OUT

IN

SENSE/

ADJ*

5

4

3

2

1

SENSE/ADJ*

OUT

5

4

3

2

1

OUT

IN

1±

OUT

GND

IN

OUT

IN

TAB IS

GND

SENSE/ADJ*

GND

NC

IN

SHDN

GND

SHDN

GND

TAB IS

GND

T PACKAGE

5-LEAD PLASTIC TO-220

Q PACKAGE

5-LEAD PLASTIC DD

FE PACKAGE

*PIN 5 = SENSE FOR LT1963A-1.5/LT1963A-1.8/

LT1963A-2.5/LT1963A-3.3

*PIN 5 = SENSE FOR LT1963A-1.5/LT1963A-1.8/

LT1963A-2.5/LT1963A-3.3

16-LEAD PLASTIC TSSOP

EXPOSED PAD (PIN 1±) IS GND. MUST BE

SOLDERED TO THE PCB.

= ADJ FOR LT1963A

*PIN 6 = SENSE FOR LT1963A-1.5/LT1963A-1.8/

LT1963A-2.5/LT1963A-3.3

T

JMAX

= 150°C, θ = 50°C/ W

T

JMAX

= 150°C, θ = 30°C/ W

JA

= ADJ FOR LT1963A

T

= 150°C, θ = 38°C/ W

JMAX

JA

FRONT VIEW

TOP VIEW

3

2

1

OUT

SENSE/ADJ*

GND

1

2

3

4

8

±

6

5

IN

OUT

GND

IN

GND

SHDN

TAB IS

GND

NC

S8 PACKAGE

8-LEAD PLASTIC SO

ST PACKAGE

3-LEAD PLASTIC SOT-223

*PIN 2 = SENSE FOR LT1963A-1.5/LT1963A-1.8/

LT1963A-2.5/LT1963A-3.3

T

JMAX

= 150°C, θ = 50°C/ W

JA

= ADJ FOR LT1963A

T

JMAX

= 150°C, θ = ±0°C/ W

JA

1963afd

2

LT1963A Series

ORDER INFORMATION

LEAD FREE FINISH

TAPE AND REEL

PART MARKING*

LT1963AEQ

LT1963AIQ

LT1963AMPQ

LT1963AEQ-1.5

LT1963AEQ-1.8

LT1963AEQ-2.5

LT1963AEQ-3.3

LT1963AET

LT1963AIT

PACKAGE DESCRIPTION

TEMPERATURE RANGE

–40°C to 125°C

–55°C to 125°C

–40°C to 125°C

–55°C to 125°C

–40°C to 125°C

TEMPERATURE RANGE

–40°C to 125°C

–55°C to 125°C

–40°C to 125°C

LT1963AEQ#PBF

LT1963AEQ#TRPBF

LT1963AIQ#TRPBF

5-Lead Plastic DD-PAK

5-Lead Plastic TO-220

16-Lead Plastic TSSOP

3-Lead Plastic SOT-223

8-Lead Plastic SO

LT1963AIQ#PBF

LT1963AMPQ#PBF

LT1963AEQ-1.5#PBF

LT1963AEQ-1.8#PBF

LT1963AEQ-2.5#PBF

LT1963AEQ-3.3#PBF

LT1963AET#PBF

LT1963AMPQ#TRPBF

LT1963AEQ-1.5#TRPBF

LT1963AEQ-1.8#TRPBF

LT1963AEQ-2.5#TRPBF

LT1963AEQ-3.3#TRPBF

LT1963AET#TRPBF

LT1963AIT#PBF

LT1963AIT#TRPBF

LT1963AET-1.5#PBF

LT1963AET-1.8#PBF

LT1963AET-2.5#PBF

LT1963AET-3.3#PBF

LT1963AEFE#PBF

LT1963AIFE#PBF

LT1963AEFE-1.5#PBF

LT1963AEFE-1.8#PBF

LT1963AEFE-2.5#PBF

LT1963AEFE-3.3#PBF

LT1963AEST-1.5#PBF

LT1963AEST-1.8#PBF

LT1963AEST-2.5#PBF

LT1963AEST-3.3#PBF

LT1963AES8#PBF

LT1963AIS8#PBF

LT1963AMPS8#PBF

LT1963AES8-1.5#PBF

LT1963AES8-1.8#PBF

LT1963AES8-2.5#PBF

LT1963AES8-3.3#PBF

LEAD BASED FINISH

LT1963AEQ

LT1963AET-1.5#TRPBF

LT1963AET-1.8#TRPBF

LT1963AET-2.5#TRPBF

LT1963AET-3.3#TRPBF

LT1963AEFE#TRPBF

LT1963AIFE#TRPBF

LT1963AEFE-1.5#TRPBF

LT1963AEFE-1.8#TRPBF

LT1963AEFE-2.5#TRPBF

LT1963AEFE-3.3#TRPBF

LT1963AEST-1.5#TRPBF

LT1963AEST-1.8#TRPBF

LT1963AEST-2.5#TRPBF

LT1963AEST-3.3#TRPBF

LT1963AES8#TRPBF

LT1963AIS8#TRPBF

LT1963AMPS8#TRPBF

LT1963AES8-1.5#TRPBF

LT1963AES8-1.8#TRPBF

LT1963AES8-2.5#TRPBF

LT1963AES8-3.3#TRPBF

TAPE AND REEL

LT1963AET-1.5

LT1963AET-1.8

LT1963AET-2.5

LT1963AET-3.3

1963AEFE

1963AIFE

1963AEFE15

1963AEFE18

1963AEFE25

1963AEFE33

963A15

963A18

963A25

963A33

1963A

8-Lead Plastic SO

963AMP

8-Lead Plastic SO

963A15

8-Lead Plastic SO

963A18

8-Lead Plastic SO

963A25

8-Lead Plastic SO

963A33

8-Lead Plastic SO

PART MARKING*

LT1963AEQ

LT1963AIQ

LT1963AMPQ

LT1963AEQ-1.5

LT1963AEQ-1.8

LT1963AEQ-2.5

LT1963AEQ-3.3

LT1963AET

LT1963AIT

PACKAGE DESCRIPTION

5-Lead Plastic DD-PAK

5-Lead Plastic TO-220

LT1963AEQ#TR

LT1963AIQ

LT1963AIQ#TR

LT1963AMPQ

LT1963AMPQ#TR

LT1963AEQ-1.5

LT1963AEQ-1.5#TR

LT1963AEQ-1.8#TR

LT1963AEQ-2.5#TR

LT1963AEQ-3.3#TR

LT1963AET#TR

LT1963AEQ-1.8

LT1963AEQ-2.5

LT1963AEQ-3.3

LT1963AET

LT1963AIT

LT1963AIT#TR

1963afd

3

LT1963A Series

ORDER INFORMATION

LEAD BASED FINISH

LT1963AET-1.5

LT1963AET-1.8

LT1963AET-2.5

LT1963AET-3.3

LT1963AEFE

TAPE AND REEL

PART MARKING*

LT1963AET-1.5

LT1963AET-1.8

LT1963AET-2.5

LT1963AET-3.3

1963AEFE

1963AIFE

1963AEFE15

1963AEFE18

1963AEFE25

1963AEFE33

963A15

PACKAGE DESCRIPTION

5-Lead Plastic TO-220

16-Lead Plastic TSSOP

3-Lead Plastic SOT-223

8-Lead Plastic SO

TEMPERATURE RANGE

–40°C to 125°C

–55°C to 125°C

–40°C to 125°C

LT1963AET-1.5#TR

LT1963AET-1.8#TR

LT1963AET-2.5#TR

LT1963AET-3.3#TR

LT1963AEFE#TR

LT1963AIFE

LT1963AIFE#TR

LT1963AEFE-1.5

LT1963AEFE-1.8

LT1963AEFE-2.5

LT1963AEFE-3.3

LT1963AEST-1.5

LT1963AEST-1.8

LT1963AEST-2.5

LT1963AEST-3.3

LT1963AES8

LT1963AEFE-1.5#TR

LT1963AEFE-1.8#TR

LT1963AEFE-2.5#TR

LT1963AEFE-3.3#TR

LT1963AEST-1.5#TR

LT1963AEST-1.8#TR

LT1963AEST-2.5#TR

LT1963AEST-3.3#TR

LT1963AES8#TR

963A18

963A25

963A33

1963A

LT1963AIS8

LT1963AIS8#TR

1963A

8-Lead Plastic SO

LT1963AMPS8

LT1963AES8-1.5

LT1963AES8-1.8

LT1963AES8-2.5

LT1963AES8-3.3

LT1963AMPS8#TR

LT1963AES8-1.5#TR

LT1963AES8-1.8#TR

LT1963AES8-2.5#TR

LT1963AES8-3.3#TR

963AMP

8-Lead Plastic SO

963A15

8-Lead Plastic SO

963A18

8-Lead Plastic SO

963A25

8-Lead Plastic SO

963A33

8-Lead Plastic SO

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/

1963afd

4

LT1963A Series

The l denotes speciﬁcations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise speciﬁcations are at T_A= 25°C. (Note 3)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Minimum Input Voltage (Notes 4,12)

I

= 0.5A

= 1.5A

1.9

2.1

V

LOAD

l

2.5

Regulated Output Voltage (Note 5)

LT1963A-1.5

LT1963A-1.8

LT1963A-2.5

LT1963A-3.3

LT1963A

V

= 2.21V, I

= 1mA

1.4±±

1.44±

1.500

1.523

1.545

V

IN

LOAD

2.5V < V < 20V, 1mA < I

< 1.5A

IN

LOAD

V

IN

= 2.3V, I

= 1mA

1.±±3

1.±3±

1.800

1.82±

1.854

V

LOAD

2.8V < V < 20V, 1mA < I

IN

V

IN

= 3V, I

= 1mA

LOAD

2.462

2.412

2.500

2.538

2.5±5

V

3.5V < V < 20V, 1mA < I

IN

V

IN

= 3.8V, I

= 1mA

3.250

3.200

3.300

3.350

3.400

V

LOAD

4.3V < V < 20V, 1mA < I

IN

ADJ Pin Voltage (Notes 4, 5)

Line Regulation

V

IN

= 2.21V, I

= 1mA

1.192

1.1±4

1.210

1.228

1.246

V

LOAD

2.5V < V < 20V, 1mA < I

IN

l

LT1963A-1.5

LT1963A-1.8

LT1963A-2.5

LT1963A-3.3

ΔV = 2.21V to 20V, I

= 1mA

LOAD

2.0

2.5

3.0

3.5

1.5

6

±

10

5

mV

IN

ΔV = 2.3V to 20V, I

= 1mA

LOAD

ΔV = 3V to 20V, I

= 1mA

ΔV = 3.8V to 20V, I

= 1mA

LOAD

LT1963A (Note 4) ΔV = 2.21V to 20V, I

IN

Load Regulation

LT1963A-1.5

LT1963A-1.8

LT1963A-2.5

LT1963A-3.3

LT1963A (Note 4)

V

= 2.5V, ΔI

= 1mA to 1.5A

2

9

mV

IN

LOAD

●

18

V

= 2.8V, ΔI

= 1mA to 1.5A

2

10

20

mV

IN

LOAD

V

= 3.5V, ΔI

= 1mA to 1.5A

2.5

3

15

30

mV

IN

LOAD

V

= 4.3V, ΔI

= 1mA to 1.5A

20

35

mV

IN

LOAD

V

= 2.5V, ΔI

= 1mA to 1.5A

2

8

15

mV

IN

LOAD

Dropout Voltage

= V

I

= 1mA

0.02

0.10

0.19

0.34

0.06

0.10

V

LOAD

V

IN

OUT(NOMINAL)

(Notes 6, ±, 12)

I

= 100mA

0.1±

0.22

V

LOAD

I

= 500mA

0.2±

0.35

V

LOAD

I

= 1.5A

0.45

0.55

V

LOAD

GND Pin Current

I

= 0mA

●

1.0

1.1

3.8

15

1.5

1.6

5.5

25

mA

LOAD

V

= V

+ 1V

OUT(NOMINAL)

= 1mA

IN

(Notes 6, 8)

= 100mA

= 500mA

= 1.5A

80

120

Output Voltage Noise

ADJ Pin Bias Current

Shutdown Threshold

C

= 10μF, I

= 1.5A, BW = 10Hz to 100kHz

40

3

μV

RMS

OUT

LOAD

(Notes 4, 9)

10

2

μA

V

OUT

V

OUT

= Off to On

= On to Off

●

0.90

0.±5

V

0.25

SHDN Pin Current (Note 10)

V

SHDN

V

SHDN

= 0V

= 20V

0.01

3

1

30

μA

Quiescent Current in Shutdown

V

IN

= 6V, V

= 0V

SHDN

0.01

1

μA

1963afd

5

LT1963A Series

The l denotes speciﬁcations which apply over the full operating

ELECTRICAL CHARACTERISTICS

temperature range, otherwise speciﬁcations are at T_A= 25°C. (Note 3)

PARAMETER

CONDITIONS

– V = 1.5V (Avg), V

MIN

TYP

MAX

UNITS

Ripple Rejection

V

= 0.5V ,

P-P

55

63

dB

IN

OUT

RIPPLE

f

= 120Hz, I

= 0.±5A

LOAD

RIPPLE

Current Limit

V

IN

V

IN

= ±V, V

= 0V

2

A

OUT

●

= V

+ 1V, ΔV

= –0.1V

OUT

1.6

OUT(NOMINAL)

Input Reverse Leakage Current (Note 13) Q, T, S8 Packages

ST Package

V

IN

V

IN

= –20V, V

= 0

●

1

2

mA

OUT

Reverse Output Current (Note 11)

LT1963A-1.5

LT1963A-1.8

LT1963A-2.5

LT1963A-3.3

LT1963A (Note 4)

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

= 1.5V, V < 1.5V

600

300

1200

600

μA

IN

= 1.8V, V < 1.8V

IN

= 2.5V, V < 2.5V

IN

= 3.3V, V < 3.3V

IN

= 1.21V, V < 1.21V

IN

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: Absolute maximum input to output differential voltage can not

be achieved with all combinations of rated IN pin and OUT pin voltages.

With the IN pin at 20V, the OUT pin may not be pulled below 0V. The total

measured voltage from IN to OUT can not exceed ±20V.

Note 6: To satisfy requirements for minimum input voltage, the LT1963A

(adjustable version) is tested and speciﬁed for these conditions with an

external resistor divider (two 4.12k resistors) for an output voltage of 2.4V.

The external resistor divider will add a 300μA DC load on the output.

Note 7: Dropout voltage is the minimum input to output voltage differential

needed to maintain regulation at a speciﬁed output current. In dropout, the

output voltage will be equal to: V – V

.

IN

DROPOUT

Note 8: GND pin current is tested with V = V

+ 1V and a

IN

OUT(NOMINAL)

current source load. The GND pin current will decrease at higher input

voltages.

Note 3: The LT1963A regulators are tested and speciﬁed under pulse load

conditions such that T ≈ T . The LT1963AE is 100% tested at T = 25°C.

J

A

Note 9: ADJ pin bias current ﬂows into the ADJ pin.

Note 10: SHDN pin current ﬂows into the SHDN pin.

Note 11: Reverse output current is tested with the IN pin grounded and the

OUT pin forced to the rated output voltage. This current ﬂows into the OUT

pin and out the GND pin.

Note 12: For the LT1963A, LT1963A-1.5 and LT1963A-1.8 dropout voltage

will be limited by the minimum input voltage speciﬁcation under some

output voltage/load conditions.

Note 13: For the ST package, the input reverse leakage current increases

due to the additional reverse leakage current for the SHDN pin, which is

tied internally to the IN pin.

Performance at –40°C and 125°C is assured by design, characterization and

correlation with statistical process controls. The LT1963AI is guaranteed

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

LT1963AMP is 100% tested and guaranteed over the –55°C to 125°C

operating junction temperature range.

Note 4: The LT1963A (adjustable version) is tested and speciﬁed for these

conditions with the ADJ pin connected to the OUT pin.

Note 5: Operating conditions are limited by maximum junction

temperature. The regulated output voltage speciﬁcation will not apply

for all possible combinations of input voltage and output current. When

operating at maximum input voltage, the output current range must be

limited. When operating at maximum output current, the input voltage

range must be limited.

1963afd

6

LT1963A Series

TYPICAL PERFORMANCE CHARACTERISTICS

Typical Dropout Voltage

Guaranteed Dropout Voltage

Dropout Voltage

500

450

400

350

300

250

200

150

100

50

500

450

400

350

300

250

200

150

100

50

600

500

400

300

200

100

0

= TEST POINTS

T

J

≤ 125°C

T = 125°C

J

I

= 1.5A

L

T

J

≤ 25°C

T = 25°C

J

I

= 0.5A

L

I

= 100mA

L

I

= 1mA

L

0

1.4

0

0.8

1.2 1.4

0.2 0.4 0.6 0.8 1.0 1.2

OUTPUT CURRENT (A)

1.6

0.2 0.4 0.6

1.0

1.6

–50

0

25

50

±5 100 125

–25

OUTPUT CURRENT (A)

TEMPERATURE (°C)

1963A G01

1963A G02

1963A G03

Quiescent Current

LT1963A-1.8 Output Voltage

LT1963A-1.5 Output Voltage

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

1.54

1.84

1.83

1.82

1.81

1.80

1.±9

1.±8

1.±±

1.±6

I

L

= 1mA

I

L

= 1mA

1.53

1.52

LT1963A-1.5/1.8/-2.5/-3.3

1.51

1.50

1.49

1.48

1.4±

LT1963A

V

= 6V

IN

L

R

= ∞, I = 0

L

V

= V

IN

SHDN

1.46

50

TEMPERATURE (°C)

100 125

–50 –25

0

25

±5

–25

0

25

50

±5

125

–50

100

–25

0

50

±5 100 125

–50

25

TEMPERATURE (°C)

1963A G04

1963A G05

1963A G40

LT1963A-2.5 Output Voltage

LT1963A-3.3 Output Voltage

LT1963A ADJ Pin Voltage

2.58

2.56

2.54

2.52

2.50

2.48

2.46

2.44

2.42

3.38

3.36

3.34

3.32

3.30

3.28

3.26

3.24

3.22

1.230

1.225

1.220

1.215

1.210

1.205

1.200

1.195

1.190

I

L

= 1mA

I

L

= 1mA

I = 1mA

L

–25

0

25

50

±5

125

–25

0

25

50

±5

125

–25

0

25

50

±5

125

–50

100

–50

100

–50

100

TEMPERATURE (°C)

1963A G06

1963A G0±

1963A G08

1963afd

7

LT1963A Series

TYPICAL PERFORMANCE CHARACTERISTICS

LT1963A-2.5 Quiescent Current

LT1963A-1.5 Quiescent Current

LT1963A-1.8 Quiescent Current

14

12

14

12

10

8

14

12

10

8

T

R

V

= 25°C

= ∞

SHDN

T = 25°C

J

L

T = 25°C

J

R

V

= ∞

R

V

= ∞

L

= V

IN

= V

SHDN IN

SHDN

IN

10

8

6

4

2

6

4

2

0

5

6

±

8

9

10

0

3

5

6

±

8

9

10

0

3

4

5

6

±

8

9

10

0

1

2

3

4

1

2

4

1

2

INPUT VOLTAGE (V)

1963A G09

1963A G10

1963A G41

LT1963A Quiescent Current

LT1963A-1.5 GND Pin Current

LT1963A-3.3 Quiescent Current

25

20

15

14

12

10

8

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

T

= 25°C

= V

T = 25°C

J

T = 25°C

J

R

V

R

V

= ∞

SHDN

IN

= 4.3k

L

*FOR V

= 1.5V

= V

OUT

V

= V

SHDN

IN

SHDN

IN

R

L

= 150, I = 10mA*

L

6

R

L

= 5, I = 300mA*

L

10

5

4

R

L

= 15, I = 100mA*

L

2

0

1

2

3

4

5

6

±

8

9

10

0

3

4

5

6

±

8

9

10

0

1

2

0

6

8

10 12 14 16 18 20

2

4

INPUT VOLTAGE (V)

1963A G11

1963A G42

1963A G12

LT1963A-1.8 GND Pin Current

LT1963A-3.3 GND Pin Current

LT1963A-2.5 GND Pin Current

25

20

15

10

5

25

20

15

10

5

25

20

15

10

5

T = 25°C

J

T = 25°C

J

T = 25°C

J

V

= V

V

= V

V

SHDN

= V

SHDN

IN

SHDN

IN

*FOR V

= 1.8V

*FOR V

= 3.3V

*FOR V

= 2.5V

OUT

R

= 8.33, I = 300mA*

L

R

= 11, I = 300mA*

L

R

L

= 6, I = 300mA*

L

R

= 25, I = 100mA*

L

R

L

= 33, I = 100mA*

L

R

L

= 18, I = 100mA*

L

R

2

= 180, I = 10mA*

L

R

= 250, I = 10mA*

R

3

= 330, I = 100mA*

L L

L

0

1

2

4

5

6

±

8

9

10

0

1

3

4

5

6

±

8

9 10

0

1

2

3

4

5

6

±

8

9 10

INPUT VOLTAGE (V)

1963A G15

1963A G13

1963A G14

1963afd

8

LT1963A Series

TYPICAL PERFORMANCE CHARACTERISTICS

LT1963A GND Pin Current

LT1963A-1.5 GND Pin Current

LT1963A-1.8 GND Pin Current

100

90

80

±0

60

50

40

30

20

10

0

10

8

100

90

80

±0

60

50

40

30

20

10

0

T

= 25°C

= V

IN

T

= 25°C

= V

J

T = 25°C

J

V

SHDN

V

SHDN

= V

SHDN

IN

*FOR V

= 1.5V

*FOR V

= 1.8V

OUT

*FOR V

= 1.21V

OUT

R

L

= 4.33, I = 300mA*

L

R

= 1.2, I = 1.5A*

L

6

L

R

L

= 1, I = 1.5A*

L

R

L

= 1.5, I = 1A*

L

4

R

= 1.8, I = 1A*

L

R

L

= 12.1, I = 100mA*

L

R

= 3, I = 500mA*

L

2

R

= 3.6, I = 500mA*

L

R

L

= 121, I = 10mA*

L

0

4

0

1

2

3

5

6

±

8

9

10

0

1

2

3

4

5

6

±

8

9 10

0

1

2

3

4

5

6

±

8

9

10

INPUT VOLTAGE (V)

1963A G1±

1963A G16

1963A G43

LT1963A-2.5 GND Pin Current

LT1963A GND Pin Current

LT1963A-3.3 GND Pin Current

100

90

80

±0

60

50

40

30

20

10

0

100

90

80

±0

60

50

40

30

20

10

0

100

90

80

±0

60

50

40

30

20

10

0

T

V

= 25°C

= V

T

= 25°C

= V

J

T

V

= 25°C

= V

J

V

SHDN

IN

SHDN

IN

SHDN

IN

*FOR V

= 3.3V

*FOR V

= 1.21V

OUT

*FOR V

= 2.5V

OUT

R

= 2.2, I = 1.5A*

L

R

L

= 1.6±, I = 1.5A*

L

R

L

= 0.81, I = 1.5A*

L

R

= 2.5, I = 1A*

L

R

= 3.3, I = 1A*

L

R

= 1.21, I = 1A*

L

R

= 5, I = 500mA*

L

R

= 6.6, I = 500mA*

L

R

L

= 2.42, I = 500mA*

L

4

0

1

2

3

4

6

±

8

9

10

4

0

1

2

3

5

6

±

8

9

10

5

0

1

2

3

6

±

8

9

10

5

INPUT VOLTAGE (V)

1963A G18

1963A G19

1963A G20

GND Pin Current vs I_LOAD

SHDN Pin Threshold (Off-to-On)

SHDN Pin Threshold (On-to-Off)

1.0

0.9

0.8

0.±

0.6

0.5

0.4

0.3

0.2

0.1

0

1.0

0.9

0.8

0.±

0.6

0.5

0.4

0.3

0.2

0.1

0

100

90

80

±0

60

50

40

30

20

10

0

I

= 1mA

V

IN

= V

+1V

L

OUT (NOMINAL)

I

= 1.5A

L

I

= 1mA

L

–50

0

25

50

±5 100 125

–50

0

25

50

±5 100 125

–25

0.8

OUTPUT CURRENT (A)

0

0.2 0.4 0.6

1.0 1.2 1.4 1.6

TEMPERATURE (°C)

1963A G22

1963A G23

1963A G21

1963afd

9

LT1963A Series

TYPICAL PERFORMANCE CHARACTERISTICS

SHDN Pin Input Current

ADJ Pin Bias Current

±

6

5

4

3

2

1

0

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

V

= 20V

SHDN

50

100 125

–50 –25

0

25

±5

8

–50

0

25

TEMPERATURE (°C)

50

±5 100 125

0

2

4

6

10 12 14 16 18 20

–25

TEMPERATURE (°C)

SHDN PIN VOLTAGE (V)

1963A G25

1963A G24

1963A G26

Current Limit

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

3.0

2.5

2.0

1.5

1.0

0.5

0

V

= ±V

IN

OUT

= 0V

T = 25°C

J

T = –50°C

J

T = 125°C

J

ΔV

= 100mV

OUT

4

–50

0

25

50

±5 100 125

–25

0

2

6

8

10 12 14 16 18 20

TEMPERATURE (°C)

INPUT/OUTPUT DIFFERENTIAL (V)

1963A G28

1963A G2±

Reverse Output Current

1.0

0.9

0.8

0.±

0.6

0.5

0.4

0.3

0.2

0.1

0

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

V

= 0V

IN

= 1.21V (LT1963A)

OUT

LT1963A-1.8

LT1963A-1.5

= 1.5V (LT1963A-1.5)

= 1.8V (LT1963A-1.8)

= 2.5V (LT1963A-2.5)

= 3.3V (LT1963A-3.3)

LT1963A

LT1963A-1.8/-2.5/-3.3

LT1963A-3.3

T

= 25°C

IN

J

V

LT1963A

= 0V

LT1963A-2.5

CURRENT FLOWS INTO

OUTPUT PIN

V

= V

FB

(LT1963A)

OUT

ADJ

= V (LT1963A-1.5/1.8/-2.5/-3.3)

4

50

TEMPERATURE (°C)

125

0

1

2

3

5

6

±

8

9

10

–50

0

25

±5 100

–25

OUTPUT VOLTAGE (V)

1963A G29

1963A G30

1963afd

10

LT1963A Series

TYPICAL PERFORMANCE CHARACTERISTICS

Ripple Rejection

LT1963A Minimum Input Voltage

80

±0

60

50

40

30

20

10

0

±6

±4

±2

±0

68

66

64

62

3.0

2.5

2.0

1.5

1.0

0.5

0

I

L

= 1.5A

I

L

= 500mA

I

L

= 100mA

C

OUT

= 100μF TANTALUM

+10 × 1μF CERAMIC

C

OUT

= 10μF TANTALUM

I

= 0.±5A

L

I

= 0.±5A

L

V

= V

+1V + 0.5V

IN

OUT(NOMINAL) P-P

V

= V

+1V + 50mV

RIPPLE

RMS

IN

OUT(NOMINAL)

RIPPLE AT f = 120Hz

–50 –25 25

TEMPERATURE (°C)

10

100

1k

10k

100k

1M

50

100 125

50

TEMPERATURE (°C)

100 125

0

±5

–50

–25

0

25

±5

FREQUENCY (Hz)

1963A G31

1963A G32

1963A G33

Load Regulation

Output Noise Spectral Density

10

1.0

0.1

C

L

= 10μF

OUT

I

=1.5A

5

0

LT1963A-1.5

LT1963A

LT1963A-2.5

LT1963A-1.8

LT1963A-3.3

–5

LT1963A-2.5

LT1963A-3.3

–10

–15

–20

LT1963A

V

= V

+1V

OUT(NOMINAL)

IN

LT1963A-1.8

LT1963A-1.5

(LT1963A-1.8/-2.5/-3.3)

= 2.±V (LT1963A/LT1963A-1.5)

IN

L

ΔI = 1mA TO 1.5A

0.01

50

100 125

–50 –25

0

25

±5

10

100

1k

10k

100k

FREQUENCY (Hz)

TEMPERATURE (°C)

1963A G35

1963A G34

RMS Output Noise vs Load

Current (10Hz to 100kHz)

LT1963A-3.3 10Hz to 100kHz Output Noise

50

C

OUT

= 10μF

45

40

35

30

25

20

15

10

5

LT1963A-3.3

LT1963A-2.5

LT1963A-1.8

V

OUT

100μV/DIV

LT1963A-1.5

LT1963A

0

1963A G3±

C

LOAD

= 10μF

= 1.5A

0.0001 0.001

0.01

0.1

1

10

1ms/DIV

OUT

I

LOAD CURRENT (A)

1963A G36

1963afd

11

LT1963A Series

TYPICAL PERFORMANCE CHARACTERISTICS

LT1963A-3.3 Transient Response

200

150

100

50

V

C

= 4.3V

IN

= 3.3μF TANTALUM

150

100

50

= 10μF TANTALUM

OUT

0

–50

–100

–150

1.5

1.0

0.5

0

–50

–100

0.6

0.4

0.2

0

V

C

= 4.3V

IN

= 33μF TANTALUM

= 100μF TANTALUM

OUT

+10 × 1μF CERAMIC

8

0

2

4

6

10 12 14 16 18 20

250

300 350 400 450 500

0

50 100 150 200

TIME (μs)

1963A G38

1963A G39

1963afd

12

LT1963A Series

PIN FUNCTIONS

OUT: Output. The output supplies power to the load.

A minimum output capacitor of 10μF is required to

prevent oscillations. Larger output capacitors will be

required for applications with large transient loads to limit

peak voltage transients. See the Applications Information

section for more information on output capacitance and

reverse output characteristics.

be off when the SHDN pin is pulled low. The SHDN pin can

be driven either by 5V logic or open-collector logic with a

pull-up resistor. The pull-up resistor is required to supply

the pull-up current of the open-collector gate, normally

severalmicroamperes,andtheSHDNpincurrent,typically

3μA. If unused, the SHDN pin must be connected to V .

IN

The device will be in the low power shutdown state if the

SHDN pin is not connected.

SENSE: Sense. For ﬁxed voltage versions of the LT1963A

(LT1963A-1.5/LT1963A-1.8/LT1963A-2.5/LT1963A-3.3),

the SENSE pin is the input to the error ampliﬁer. Optimum

regulation will be obtained at the point where the SENSE

pin is connected to the OUT pin of the regulator. In criti-

cal applications, small voltage drops are caused by the

IN: Input. Power is supplied to the device through the IN

pin. A bypass capacitor is required on this pin if the device

is more than six inches away from the main input ﬁlter

capacitor. In general, the output impedance of a battery

rises with frequency, so it is advisable to include a bypass

capacitor in battery-powered circuits. A bypass capacitor

in the range of 1μF to 10μF is sufﬁcient. The LT1963A

regulators are designed to withstand reverse voltages

on the IN pin with respect to ground and the OUT pin. In

the case of a reverse input, which can happen if a battery

is plugged in backwards, the device will act as if there is

a diode in series with its input. There will be no reverse

current ﬂow into the regulator and no reverse voltage

will appear at the load. The device will protect both itself

and the load.

resistance (R ) of PC traces between the regulator and the

P

load. These may be eliminated by connecting the SENSE

pin to the output at the load as shown in Figure 1 (Kelvin

Sense Connection). Note that the voltage drop across

the external PC traces will add to the dropout voltage of

the regulator. The SENSE pin bias current is 600μA at

the nominal rated output voltage. The SENSE pin can be

pulled below ground (as in a dual supply system where

the regulator load is returned to a negative supply) and

still allow the device to start and operate.

ADJ: Adjust. For the adjustable LT1963A, this is the input

to the error ampliﬁer. This pin is internally clamped to ±±V.

It has a bias current of 3μA which ﬂows into the pin. The

ADJ pin voltage is 1.21V referenced to ground and the

output voltage range is 1.21V to 20V.

IN

OUT

LT1963A

R

P

+

SHDN SENSE

LOAD

V

IN

GND

R

P

1963A F01

SHDN:Shutdown.TheSHDNpinisusedtoputtheLT1963A

regulatorsintoalowpowershutdownstate.Theoutputwill

Figure 1. Kelvin Sense Connection

1963afd

13

LT1963A Series

APPLICATIONS INFORMATION

The LT1963A series are 1.5A low dropout regulators opti-

mized for fast transient response. The devices are capable

of supplying 1.5A at a dropout voltage of 350mV. The low

operating quiescent current (1mA) drops to less than 1μA

in shutdown. In addition to the low quiescent current, the

LT1963Aregulatorsincorporateseveralprotectionfeatures

whichmakethemidealforuseinbattery-poweredsystems.

The devices are protected against both reverse input and

reverse output voltages. In battery backup applications

where the output can be held up by a backup battery when

the input is pulled to ground, the LT1963A-X acts like it

has a diode in series with its output and prevents reverse

current ﬂow. Additionally, in dual supply applications

where the regulator load is returned to a negative supply,

the output can be pulled below ground by as much as 20V

and still allow the device to start and operate.

IN

OUT

V

OUT

+

V

IN

R2

R1

LT1963A

ADJ

ꢀ

ꢃ

R2

V_OUT=1.21V 1+

+ I

(

R2

_ADJ)( )

ꢂ

ꢅ

ꢁ

R1ꢄ

GND

V

_ADJ=1.21V

_ADJ=3μA AT 25°C

OUTPUT RANGE = 1.21V TO 20V

I

1963A F02

Figure 2. Adjustable Operation

make it stable. For the LT1963A, the frequency compensa-

tion is both internal and external—the output capacitor.

The size of the output capacitor, the type of the output

capacitor, and the ESR of the particular output capacitor

all affect the stability.

In addition to stability, the output capacitor also affects

the high frequency transient response. The regulator

loop has a ﬁnite band width. For high frequency transient

loads, recovery from a transient is a combination of the

output capacitor and the bandwidth of the regulator. The

LT1963A was designed to be easy to use and accept a

wide variety of output capacitors. However, the frequency

compensationisaffectedbytheoutputcapacitorandopti-

mumfrequencystabilitymayrequiresomeESR,especially

with ceramic capacitors.

Adjustable Operation

The adjustable version of the LT1963A has an output volt-

age range of 1.21V to 20V. The output voltage is set by

the ratio of two external resistors as shown in Figure 2.

The device servos the output to maintain the voltage at

the ADJ pin at 1.21V referenced to ground. The current

in R1 is then equal to 1.21V/R1 and the current in R2 is

the current in R1 plus the ADJ pin bias current. The ADJ

pin bias current, 3μA at 25°C, ﬂows through R2 into the

ADJ pin. The output voltage can be calculated using the

formula in Figure 2. The value of R1 should be less than

4.1±k to minimize errors in the output voltage caused by

the ADJ pin bias current. Note that in shutdown the output

is turned off and the divider current will be zero.

Foreaseofuse,lowESRpolytantalumcapacitors(POSCAP)

are a good choice for both the transient response and

stability of the regulator. These capacitors have intrinsic

ESR that improves the stability. Ceramic capacitors have

extremely low ESR, and while they are a good choice in

many cases, placing a small series resistance element

will sometimes achieve optimum stability and minimize

ringing. In all cases, a minimum of 10μF is required while

the maximum ESR allowable is 3Ω.

The adjustable device is tested and speciﬁed with the ADJ

pin tied to the OUT pin for an output voltage of 1.21V.

Speciﬁcations for output voltages greater than 1.21V will

be proportional to the ratio of the desired output voltage

The place where ESR is most helpful with ceramics is

low output voltage. At low output voltages, below 2.5V,

some ESR helps the stability when ceramic output capaci-

tors are used. Also, some ESR allows a smaller capacitor

value to be used. When small signal ringing occurs with

ceramics due to insufﬁcient ESR, adding ESR or increas-

ing the capacitor value improves the stability and reduces

the ringing. Table 1 gives some recommended values of

ESR to minimize ringing caused by fast, hard current

transitions.

to 1.21V: V /1.21V. For example, load regulation for an

OUT

output current change of 1mA to 1.5A is –3mV typical at

V

OUT

= 1.21V. At V

= 5V, load regulation is:

OUT

(5V/1.21V)(–3mV) = –12.4mV

Output Capacitors and Stability

The LT1963A regulator is a feedback circuit. Like any

feedback circuit, frequency compensation is needed to

1963afd

14

LT1963A Series

APPLICATIONS INFORMATION

Table 1. Capacitor Minimum ESR

POSCAP capacitors are used. The output voltage is at the

worst case value of 1.2V. Trace A, is with a 10μF ceramic

outputcapacitorandshowssigniﬁcantringingwithapeak

amplitude of 25mV. For Trace B, a 22μF/45mΩ POSCAP is

added in parallel with the 10μF ceramic. The output is well

damped and settles to within 10mV in less than 20μs.

V

10μF

20mΩ

15mΩ

5mΩ

22μF

15mΩ

10mΩ

5mΩ

47μF

10mΩ

5mΩ

100μF

5mΩ

0mΩ

OUT

1.2V

1.5V

1.8V

2.5V

3.3V

≥5V

0mΩ

For Trace C, a 100μF/35mΩ POSCAP is connected in

parallel with the 10μF ceramic capacitor. In this case the

peak output deviation is less than 20mV and the output

settles in about 10μs. For improved transient response

the value of the bulk capacitor (tantalum or aluminum

electrolytic) should be greater than twice the value of the

ceramic capacitor.

0mΩ

Figures3through8showtheeffectofESRonthetransient

response of the regulator. These scope photos show the

transientresponsefortheLT1963Aatthreedifferentoutput

voltageswithvariouscapacitorsandvariousvaluesofESR.

The output load conditions are the same for all traces. In

all cases there is a DC load of 500mA. The load steps up

to 1A at the ﬁrst transition and steps back to 500mA at

the second transition.

Tantalum and Polytantalum Capacitors

There is a variety of tantalum capacitor types available,

with a wide range of ESR speciﬁcations. Older types have

ESRspeciﬁcationsinthehundredsofmΩtoseveralOhms.

Some newer types of polytantalum with multi-electrodes

havemaximumESRspeciﬁcationsaslowas5mΩ. Ingen-

eral the lower the ESR speciﬁcation, the larger the size and

the higher the price. Polytantalum capacitors have better

surge capability than older types and generally lower ESR.

Some types such as the Sanyo TPE and TPB series have

ESR speciﬁcations in the 20mΩ to 50mΩ range, which

provide near optimum transient response.

At the worst case point of 1.2V

with 10μF C

OUT

(Figure 3), a minimum amount of ESR is required. While

20mΩ is enough to eliminate most of the ringing, a value

closer to 50mΩ provides a more optimum response. At

2.5V output with 10μF C

(Figure 4) the output rings

OUT

at the transitions with 0Ω ESR but still settles to within

10mV in 20μs after the 0.5A load step. Once again a small

value of ESR will provide a more optimum response.

At 5V

with 10μF C

(Figure 5) the response is well

OUT

damped with 0Ω ESR.

Aluminum Electrolytic Capacitors

With a C of 100μF at 0Ω ESR and an output of 1.2V

Aluminumelectrolyticcapacitorscanalsobeusedwiththe

LT1963A.Thesecapacitorscanalsobeusedinconjunction

withceramiccapacitors.Thesetendtobethecheapestand

lowestperformancetypeofcapacitors. Caremustbeused

in selecting these capacitors as some types can have ESR

which can easily exceed the 3Ω maximum value.

OUT

(Figure 6), the output rings although the amplitude is

only 20mV . With C

of 100μF it takes only 5mΩ to

p-p

OUT

20mΩ of ESR to provide good damping at 1.2V output.

Performanceat2.5Vand5Voutputwith100μFC shows

similar characteristics to the 10μF case (see Figures ±-8).

OUT

At2.5V

At 5V

5mΩto20mΩcanimprovetransientresponse.

OUT

Ceramic Capacitors

the response is well damped with 0Ω ESR.

OUT

Extra consideration must be given to the use of ceramic

capacitors. Ceramic capacitors are manufactured with a

variety of dielectrics, each with different behavior over

temperature and applied voltage. The most common

dielectrics used are Z5U, Y5V, X5R and X±R. The Z5U and

CapacitortypeswithinherentlyhigherESRcanbecombined

with 0mΩ ESR ceramic capacitors to achieve both good

high frequency bypassing and fast settling time. Figure

9 illustrates the improvement in transient response that

can be seen when a parallel combination of ceramic and

1963afd

15

LT1963A Series

APPLICATIONS INFORMATION

0

5

0

V_OUT= 1.2V

I_OUT= 500mA WITH

V_OUT= 1.2V

I_OUT= 500mA WITH

500mA PULSE

C_OUT= 10μF

20

50

C

_OUT= 100μF

10

20

100

1963A F03

1963A F06

20μs/DIV

50μs/DIV

Figure 3

Figure 6

0

5

0

20

V_OUT= 2.5V

I_OUT= 500mA WITH

500mA PULSE

C_OUT= 100μF

I_OUT= 500mA WITH

500mA PULSE

C_OUT= 10μF

10

20

50

100

1963A F0±

1963A F04

50μs/DIV

20μs/DIV

Figure 4

Figure 7

0

5

0

20

V_OUT= 5V

V

_OUT= 5V

I_OUT= 500mA WITH

500mA PULSE

C_OUT= 100μF

I_OUT= 500mA WITH

500mA PULSE

C_OUT= 10μF

50

10

20

100

1963A F08

1963A F05

20μs/DIV

50μs/DIV

Figure 8

Figure 5

A

B

C

V_OUT= 1.2V

I_OUT= 500mA WITH 500mA PULSE

C_OUT

A = 10μF CERAMIC

B = 10μF CERAMIC II 22μF/45mΩ POLY

C = 10μF CERAMIC II 100μF/35mΩ POLY

=

1963A F09

50μs/DIV

Figure 9

1963afd

16

LT1963A Series

APPLICATIONS INFORMATION

Y5Vdielectricsaregoodforprovidinghighcapacitancesin

asmallpackage,butexhibitstrongvoltageandtemperature

coefﬁcients as shown in Figures 10 and 11. When used

with a 5V regulator, a 10μF Y5V capacitor can exhibit an

effective value as low as 1μF to 2μF over the operating

temperature range. The X5R and X±R dielectrics result in

more stable characteristics and are more suitable for use

as the output capacitor. The X±R type has better stability

across temperature, while the X5R is less expensive and

is available in higher values.

“FREE” Resistance with PC Traces

The resistance values shown in Table 2 can easily be made

using a small section of PC trace in series with the output

capacitor. The wide range of non-critical ESR makes it

easy to use PC trace. The trace width should be sized to

handle the RMS ripple current associated with the load.

Theoutputcapacitoronlysourcesorsinkscurrentforafew

microsecondsduringfastoutputcurrenttransitions.There

is no DC current in the output capacitor. Worst case ripple

current will occur if the output load is a high frequency

(>100kHz) square wave with a high peak value and fast

edges (< 1μs). Measured RMS value for this case is 0.5

times the peak-to-peak current change. Slower edges or

lower frequency will signiﬁcantly reduce the RMS ripple

current in the capacitor.

Voltage and temperature coefﬁcients are not the only

sources of problems. Some ceramic capacitors have a

piezoelectric response. A piezoelectric device generates

voltageacrossitsterminalsduetomechanicalstress,simi-

lartothewayapiezoelectricaccelerometerormicrophone

works. For a ceramic capacitor the stress can be induced

by vibrations in the system or thermal transients.

Table 2. PC Trace Resistors

10mΩ

20mΩ

30mΩ

"

0.5oz C

1.0oz C

2.0oz C

Width

0.011 (0.28mm)

U

"

Length

0.102 (2.6mm)

0.204 (5.2mm)

0.30± (±.8mm)

"

Width

Length

0.006 (0.15mm)

"

0.110 (2.8mm)

0.220 (5.6mm)

0.330 (8.4mm)

"

Width

Length

0.006 (0.15mm)

"

0.224 (5.±mm)

0.450 (11.4mm)

0.6±0 (1±mm)

40

20

0

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10μF

X5R

0

–20

–40

–60

–80

–100

–20

–40

–60

–80

Y5V

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10μF

–100

–50

0

8

12 14

50

TEMPERATURE (°C)

100 125

2

4

6

10

16

25

±5

–25

0

DC BIAS VOLTAGE (V)

1963A F10

1963A F11

Figure 11. Ceramic Capacitor Temperature Characteristics

Figure 10. Ceramic Capacitor DC Bias Characteristics

1963afd

17

LT1963A Series

APPLICATIONS INFORMATION

This resistor should be made using one of the inner

layers of the PC board which are well deﬁned. The resistiv-

ity is determined primarily by the sheet resistance of the

copper laminate with no additional plating steps. Table

2 gives some sizes for 0.±5A RMS current for various

copper thicknesses. More detailed information regarding

resistors made from PC traces can be found in Application

Note 69, Appendix A.

40nV/√Hz over this frequency bandwidth for the LT1963A

(adjustableversion).Forhigheroutputvoltages(generated

byusingaresistordivider),theoutputvoltagenoisewillbe

gained up accordingly. This results in RMS noise over the

10Hz to 100kHz bandwidth of 14μV

for the LT1963A

RMS

increasing to 38μV

for the LT1963A-3.3.

RMS

Higher values of output voltage noise may be measured

when care is not exercised with regard to circuit layout

and testing. Crosstalk from nearby traces can induce

unwanted noise onto the output of the LT1963A-X.

Powersupplyripplerejectionmustalsobeconsidered;the

LT1963A regulators do not have unlimited power supply

rejection and will pass a small portion of the input noise

through to the output.

Overload Recovery

LikemanyICpowerregulators,theLT1963A-Xhassafeop-

eratingareaprotection.Thesafeareaprotectiondecreases

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 protection is

designed to provide some output current at all values of

input-to-output voltage up to the device breakdown.

Thermal Considerations

Thepowerhandlingcapabilityofthedeviceislimitedbythe

maximum rated junction temperature (125°C). The power

dissipated by the device is made up of two components:

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

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, also exhibit this phenomenon, so it is not unique

to the LT1963A-X.

1. Output current multiplied by the input/output voltage

differential: (I )(V – V ), and

OUT

IN

OUT

2. GND pin current multiplied by the input voltage:

(I )(V ).

GND

IN

The GND pin current can be found using the GND Pin

CurrentcurvesintheTypicalPerformanceCharacteristics.

Power dissipation will be equal to the sum of the two

components listed above.

The problem occurs with a heavy output load when the

inputvoltageishighandtheoutputvoltageislow.Common

situations are immediately after the removal of a short-

circuit or when the shutdown pin is pulled high after the

input voltage has already been turned on. The load line for

such a load may intersect the output current curve at two

points.Ifthishappens,therearetwostableoutputoperating

points for the regulator. With this double intersection, the

input power supply may need to be cycled down to zero

and brought up again to make the output recover.

The LT1963A series regulators have internal thermal

limiting designed to protect the device during overload

conditions. For continuous normal conditions, the maxi-

mum junction temperature rating of 125°C must not be

exceeded. It is important to give careful consideration to

all sources of thermal resistance from junction to ambi-

ent. Additional heat sources mounted 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. Copper board stiffeners and plated

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

ated by power devices.

Output Voltage Noise

TheLT1963Aregulatorshavebeendesignedtoprovidelow

output voltage noise over the 10Hz to 100kHz bandwidth

whileoperatingatfullload.Outputvoltagenoiseistypically

1963afd

18

LT1963A Series

APPLICATIONS INFORMATION

The following tables list thermal resistance for several The power dissipated by the device will be equal to:

different board sizes and copper areas. All measurements

I

(V

– V ) + I (V

)

OUT(MAX) IN(MAX)

OUT

GND IN(MAX)

were taken in still air on 1/16" FR-4 board with one ounce

copper.

where,

I

= 500mA

= 6V

OUT

OUT(MAX)

Table 3. Q Package, 5-Lead DD

V

IN(MAX)

COPPER AREA

THERMAL RESISTANCE

I

at (I

= 500mA, V = 6V) = 10mA

TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)

GND

IN

2

So,

2500mm

1000mm

2500mm

23°C/W

25°C/W

33°C/W

P = 500mA(6V – 3.3V) + 10mA(6V) = 1.41W

2

125mm

Using a DD package, the thermal resistance will be in the

range of 23°C/W to 33°C/W depending on the copper

area. So the junction temperature rise above ambient will

be approximately equal to:

*Device is mounted on topside

Table 4. S0-8 Package, 8-Lead SO

COPPER AREA

TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)

THERMAL RESISTANCE

1.41W(28°C/W) = 39.5°C

2

2500mm

55°C/W

63°C/W

69°C/W

2

The maximum junction temperature will then be equal to

the maximum junction temperature rise above ambient

plus the maximum ambient temperature or:

1000mm

2

225mm

125mm

2

*Device is mounted on topside

T

= 50°C + 39.5°C = 89.5°C

JMAX

Table 5. SOT-223 Package, 3-Lead SOT-223

Protection Features

COPPER AREA

THERMAL RESISTANCE

The LT1963A regulators incorporate several protection

features which make them ideal for use in battery-pow-

ered circuits. In addition to the normal protection features

associated with monolithic regulators, such as current

limiting and thermal limiting, the devices are protected

against reverse input voltages, reverse output voltages

and reverse voltages from output to input.

TOPSIDE* BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)

2

2500mm

1000mm

2500mm

42°C/W

2

225mm

100mm

2500mm

1000mm

2500mm

1000mm

50°C/W

56°C/W

49°C/W

52°C/W

2

1000mm

2

0mm

Current limit protection and thermal overload protection

areintendedtoprotectthedeviceagainstcurrentoverload

conditionsattheoutputofthedevice.Fornormaloperation,

the junction temperature should not exceed 125°C.

*Device is mounted on topside

T Package, 5-Lead TO-220

Thermal Resistance (Junction-to-Case) = 4°C/W

The input of the device will withstand reverse voltages

of 20V. Current ﬂow into the device will be limited to less

than 1mA (typically less than 100μA) and no negative

voltage will appear at the output. The device will protect

both itself and the load. This provides protection against

batteries that can be plugged in backward.

Calculating Junction Temperature

Example: Given an output voltage of 3.3V, an input volt-

age range of 4V to 6V, an output current range of 0mA

to 500mA and a maximum ambient temperature of 50°C,

what will the maximum junction temperature be?

1963afd

19

LT1963A Series

APPLICATIONS INFORMATION

The output of the LT1963A can be pulled below ground

withoutdamagingthedevice.Iftheinputisleftopencircuit

or grounded, the output can be pulled below ground by

20V. For ﬁxed voltage versions, the output will act like a

large resistor, typically 5k or higher, limiting current ﬂow

to typically less than 600μA. For adjustable versions, the

output will act like an open circuit; no current will ﬂow out

of the pin. If the input is powered by a voltage source, the

output will source the short-circuit current of the device

and will protect itself by thermal limiting. In this case,

grounding the SHDN pin will turn off the device and stop

the output from sourcing the short-circuit current.

In circuits where a backup battery is required, several

different input/output conditions can occur. The output

voltage may be held up while the input is either pulled

to ground, pulled to some intermediate voltage, or is left

open circuit. Current ﬂow back into the output will follow

the curve shown in Figure 12.

When the IN pin of the LT1963A is forced below the OUT

pin or the OUT pin is pulled above the IN pin, input cur-

rent will typically drop to less than 2μA. This can happen

if the input of the device is connected to a discharged

(low voltage) battery and the output is held up by either

a backup battery or a second regulator circuit. The state

of the SHDN pin will have no effect on the reverse output

current when the output is pulled above the input.

The ADJ pin of the adjustable device can be pulled above

or below ground by as much as ±V without damaging the

device. Iftheinputisleftopencircuitorgrounded, theADJ

pin will act like an open circuit when pulled below ground

and like a large resistor (typically 5k) in series with a diode

when pulled above ground.

5.0

LT1963A

V

= V

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

OUT

ADJ

LT1963A-1.5

= V

V

OUT

FB

In situations where the ADJ pin is connected to a resistor

dividerthatwouldpulltheADJpinaboveits±Vclampvolt-

age if the output is pulled high, the ADJ pin input current

must be limited to less than 5mA. For example, a resistor

divider is used to provide a regulated 1.5V output from the

1.21V reference when the output is forced to 20V. The top

resistor of the resistor divider must be chosen to limit the

current into the ADJ pin to less than 5mA when the ADJ

pin is at ±V. The 13V difference between OUT and ADJ

pins divided by the 5mA maximum current into the ADJ

pin yields a minimum top resistor value of 2.6k.

LT1963A-1.8

= V

V

OUT

FB

LT1963A-2.5

= V

V

OUT

FB

LT1963A-3.3

= V

V

OUT

FB

T

= 25°C

IN

J

V

= 0V

CURRENT FLOWS

INTO OUTPUT PIN

0

1

2

3

4

5

6

±

8

9

10

OUTPUT VOLTAGE (V)

1963A F12

Figure 12. Reverse Output Current

1963afd

20

LT1963A Series

TYPICAL APPLICATIONS

SCR Pre-Regulator Provides Efﬁciency Over Line Variations

L1

500μH

LT1963A-3.3

3.3V

1.5A

OUT

IN

OUT

L2

1N4148

1k

+

10VAC AT

115V

SHDN

GND

FB

10000μF

22μF

IN

90-140

VAC

34k*

10VAC AT

115V

IN

1N4002

“SYNC”

1N4002

12.1k*

+V

2.4k

C1A

TO ALL “+V”

POINTS

200k

+

1N4148

+

1/2

22μF

±50Ω

LT1018

0.1μF

–

+V

C1B

+

±50Ω

+V

A1

0.033μF

1/2

LT1018

+

–

1N4148

10k

–

LT1006

10k

+V

1μF

+V

L1 = COILTRONICS CTX500-2-52

L2 = STANCOR P-8559

* = 1% FILM RESISTOR

= NTE543±

LT1004

1.2V

1963A TA03

1963afd

21

LT1963A Series

TYPICAL APPLICATIONS

Paralleling of Regulators for Higher Output Current

R1

0.01Ω

LT1963A-3.3

3.3V

3A

C2

22μF

IN

OUT

+

C1

100μF

V

> 3.±V

IN

SHDN

GND

FB

R2

0.01Ω

LT1963A

IN

OUT

R6

6.65k

SHDN

GND

FB

R±

4.12k

R3

2.2k

R4

2.2k

R5

1k

3

2

8

+

–

1

1/2

LT1366

C3

0.01μF

4

1963A TA05

1963afd

22

LT1963A Series

PACKAGE DESCRIPTION

Q Package

5-Lead Plastic DD Pak

(Reference LTC DWG # 05-08-1461)

.060

(1.524)

TYP

.390 – .415

(9.906 – 10.541)

.060

(1.524)

.165 – .180

(4.191 – 4.572)

.256

(6.502)

.045 – .055

(1.143 – 1.397)

15° TYP

+.008

.004

–.004

.060

(1.524)

.059

(1.499)

TYP

.183

(4.648)

.330 – .370

(8.382 – 9.398)

+0.203

–0.102

0.102

(

)

.095 – .115

(2.413 – 2.921)

.075

(1.905)

.067

(1.702)

BSC

.050 ± .012

(1.270 ± 0.305)

.300

(7.620)

.013 – .023

(0.330 – 0.584)

+.012

.143

–.020

.028 – .038

+0.305

BOTTOM VIEW OF DD PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

3.632

Q(DD5) 0502

(0.711 – 0.965)

(

)

–0.508

TYP

.420

.276

.080

.420

.350

.325

.205

.565

.320

.090

.042

.090

.042

.067

RECOMMENDED SOLDER PAD LAYOUT

NOTE:

RECOMMENDED SOLDER PAD LAYOUT

FOR THICKER SOLDER PASTE APPLICATIONS

1. DIMENSIONS IN INCH/(MILLIMETER)

2. DRAWING NOT TO SCALE

1963afd

23

LT1963A Series

PACKAGE DESCRIPTION

S8 Package

8-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610)

.189 – .197

(4.801 – 5.004)

.045

±.005

NOTE 3

.050 BSC

7

5

8

6

.245

MIN

.160

±.005

.150 – .157

(3.810 – 3.988)

NOTE 3

.228 – .244

(5.791 – 6.197)

.030

±

.005

TYP

1

3

4

2

RECOMMENDED SOLDER PAD LAYOUT

.010 – .020

(0.254 – 0.508)

× 45°

.053 – .069

(1.346 – 1.752)

.004 – .010

(0.101 – 0.254)

.008 – .010

(0.203 – 0.254)

0°– 8° TYP

.016 – .050

(0.406 – 1.270)

.050

(1.270)

BSC

.014 – .019

(0.355 – 0.483)

TYP

NOTE:

INCHES

1. DIMENSIONS IN

(MILLIMETERS)

2. DRAWING NOT TO SCALE

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

SO8 0303

1963afd

24

LT1963A Series

PACKAGE DESCRIPTION

ST Package

3-Lead Plastic SOT-223

(Reference LTC DWG # 05-08-1630)

.248 – .264

(6.30 – 6.71)

.129 MAX

.114 – .124

(2.90 – 3.15)

.059 MAX

.264 – .287

(6.70 – 7.30)

.248 BSC

.130 – .146

(3.30 – 3.71)

.039 MAX

.059 MAX

.090

BSC

.181 MAX

.033 – .041

(0.84 – 1.04)

.0905

(2.30)

BSC

RECOMMENDED SOLDER PAD LAYOUT

10° – 16°

.010 – .014

10°

MAX

.071

(1.80)

MAX

(0.25 – 0.36)

10° – 16°

.0008 – .0040

(0.0203 – 0.1016)

.024 – .033

(0.60 – 0.84)

.012

(0.31)

MIN

.181

(4.60)

BSC

ST3 (SOT-233) 0502

1963afd

25

LT1963A Series

PACKAGE DESCRIPTION

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

.165 – .180

(4.191 – 4.572)

.147 – .155

(3.734 – 3.937)

DIA

.390 – .415

(9.906 – 10.541)

.045 – .055

(1.143 – 1.397)

.230 – .270

(5.842 – 6.858)

.570 – .620

(14.478 – 15.748)

.620

(15.75)

TYP

.460 – .500

(11.684 – 12.700)

.330 – .370

(8.382 – 9.398)

.700 – .728

(17.78 – 18.491)

.095 – .115

(2.413 – 2.921)

SEATING PLANE

.152 – .202

(3.861 – 5.131)

.155 – .195*

(3.937 – 4.953)

.260 – .320

(6.60 – 8.13)

.013 – .023

(0.330 – 0.584)

.067

BSC

.135 – .165

(3.429 – 4.191)

.028 – .038

(0.711 – 0.965)

(1.70)

* MEASURED AT THE SEATING PLANE

T5 (TO-220) 0801

1963afd

26

LT1963A Series

PACKAGE DESCRIPTION

FE Package

16-Lead Plastic TSSOP (4.4mm)

(Reference LTC DWG # 05-08-1663)

Exposed Pad Variation BB

4.90 – 5.10*

(.193 – .201)

3.58

(.141)

3.58

(.141)

16 1514 13 12 1110

9

6.60 ±0.10

2.94

(.116)

4.50 ±0.10

6.40

2.94

SEE NOTE 4

(.252)

(.116)

0.45 ±0.05

BSC

1.05 ±0.10

0.65 BSC

5

7

1

2

3

4

6

8

RECOMMENDED SOLDER PAD LAYOUT

1.10

(.0433)

MAX

4.30 – 4.50*

(.169 – .177)

0.25

REF

0° – 8°

0.65

(.0256)

BSC

0.09 – 0.20

0.50 – 0.75

0.05 – 0.15

(.002 – .006)

FE16 (BB) TSSOP 0204

(.0035 – .0079)

(.020 – .030)

0.195 – 0.30

(.0077 – .0118)

TYP

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS 4. RECOMMENDED MINIMUM PCB METAL SIZE

FOR EXPOSED PAD ATTACHMENT

*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.150mm (.006") PER SIDE

MILLIMETERS

(INCHES)

2. DIMENSIONS ARE IN

3. DRAWING NOT TO SCALE

1963afd

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

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

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

27

LT1963A Series

TYPICAL APPLICATION

Adjustable Current Source

R5

0.01Ω

LT1963A-1.8

LOAD

IN

OUT

R1

1k

+

C1

10μF

SHDN

GND

FB

V

> 2.±V

IN

LT1004-1.2

R4

R6

R8

100k

R2

80.6k

C3

1μF

2.2k 2.2k

R3

2k

R±

2

3

4±0Ω

8

4

+

–

1

1/2

LT1366

C2

3.3μF

NOTE: ADJUST R1 FOR

0A TO 1.5A CONSTANT CURRENT

1963A TA04

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

V : –20V to –4.3V, V

LT11±5

500mA, Micropower, Negative LDO

= –3.8V, V = 0.50V, I = 45μA, I 10μA,

OUT(MIN) DO Q SD

IN

DD, SOT-223, PDIP8 Packages

LT1185

LT1±61

3A, Negative LDO

V : –35V to –4.2V, V

= –2.40V, V = 0.80V, I = 2.5mA, I <1μA,

IN

OUT(MIN) DO Q SD

TO220-5 Package

100mA, Low Noise Micropower, LDO

V : 1.8V to 20V, V

= 1.22V, V = 0.30V, I = 20μA, I <1μA

IN

OUT(MIN) DO Q SD

ThinSOT Package

LT1±62

LT1±63

150mA, Low Noise Micropower, LDO

500mA, Low Noise Micropower, LDO

V : 1.8V to 20V, V

= 1.22V, V = 0.30V, I = 25μA, I <1μA, MS8 Package

DO Q SD

IN

OUT(MIN)

V : 1.8V to 20V, V

IN

= 1.22V, V = 0.30V, I = 30μA, I <1μA, S8 Package

DO Q SD

LT1±64/

LT1±64A

3A, Low Noise, Fast Transient Response, V : 2.±V to 20V, V

LDO

= 1.21V, V = 0.34V, I = 1mA, I <1μA,

DO Q SD

IN

DD, TO220 Packages

LTC1844

LT1962

LT1964

LT1965

LT3020

LT3023

LT3024

150mA, Very Low Drop-Out LDO

V : 6.5V to 1.6V, V

= 1.25V, V = 0.08V, I = 40μA, I < 1μA,

DO Q SD

IN

OUT(MIN)

ThinSOTPackage

300mA, Low Noise Micropower, LDO

V : 1.8V to 20V, V

IN

= 1.22V, V = 0.2±V, I = 30μA, I <1μA, MS8 Package

DO Q SD

200mA, Low Noise Micropower,

Negative LDO

V : –0.9V to –20V, V

= –1.21V, V = 0.34V, I = 30μA, I 3μA,

OUT(MIN) DO Q SD

IN

ThinSOT Package

1.1A, Low Noise, Low Dropout Linear

Regulator

290mV Dropout Voltage, Low Noise: 40μVRMS, V : 1.8V to 20V, V : 1.2V to 19.5V,

IN OUT

stable with ceramic caps, TO-220, DDPak, MSOP and 3mm × 3mm DFN Packages

100mA, Low Voltage V

IN(MIN)

V : 0.9V to 10V, V = 0.20, V = 0.15V, I = 120μA, I <3μA,

LDO,

IN

OUT(MIN)

DO

Q

SD

V

= 0.9V

DFN, MS8 Packages

Dual, 2x 100mA, Low Noise

Micropower, LDO

V : 1.8V to 20V, V

= 1.22V, V = 0.30V, I = 40μA, I <1μA,

DO Q SD

IN

OUT(MIN)

DFN, MS10 Packages

Dual, 100mA/500mA, Low Noise

Micropower, LDO

V : 1.8V to 20V, V

= 1.22V, V = 0.30V, I = 60μA, I <1μA,

DO Q SD

IN

OUT(MIN)

DFN, TSSOP Packages

LT3080/

LT3080-1

1.1A, Parallelable, Low Noise, Low

Dropout Linear Regulator

300mV Dropout Voltage (2-Supply Operation), Low Noise: 40μVRMS, V : 1.2V to 36V,

IN

V

: 0V to 35.±V, current-based reference with 1-Resistor V

set; directly parallelable

OUT

(no op amp required), stable with ceramic caps, TO-220, SOT-223, MSOP and 3mm × 3mm

DFN Packages; “–1” version has integrated internal ballast resistor

1963afd

LT 0708 REV D • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-±41±

28

●

(408) 432-1900 FAX: (408) 434-050± www.linear.com


型号：	LT1963AES8-3.3TRPBF
厂家：	Linear
描述：	1.5A, Low Noise,Fast Transient Response LDO Regulators 1.5A ，低噪声，快速瞬态响应LDO稳压器稳压器
文件：	总28页 (文件大小：768K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT1963AES8-3.3TRPBF [Linear]

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