LINEAR TECHNOLOGY LT1764A Technical data

FEATURES

LT1764A Series

3A, Fast Transient

Response, Low Noise,

LDO Regulators

U

DESCRIPTIO

■

Optimized for Fast Transient Response

■

Output Current: 3A

■

Dropout Voltage: 340mV at 3A

■

Low Noise: 40µV

■

1mA Quiescent Current

■

Wide Input Voltage Range: 2.7V to 20V

■

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

■

No Reverse Current

■

Thermal Limiting

(10Hz to 100kHz)

RMS

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APPLICATIO S

■

3.3V to 2.5V Logic Power Supply

■

Post Regulator for Switching Supplies

The LT

®

1764A is a low dropout regulator optimized for
fast transient response. The device is capable of supplying
3A 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 regulators. In
addition to fast transient response, the LT1764A has very
low output voltage noise which makes the device ideal for
sensitive RF supply applications.

Output voltage range is from 1.21V to 20V. The LT1764A
regulators are stable with output capacitors as low as 10µF.
Internal protection circuitry includes reverse battery pro­tection, current limiting, thermal limiting and reverse cur­rent protection. The device is available in fixed output
voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an adjustable
device with a 1.21V reference voltage. The LT1764A regu­lators are available in 5-lead TO-220 and DD packages, and
16-lead FE packages.

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

All other trademarks are the property of their respective owners.

*See Applications Information Section.

TYPICAL APPLICATIO

to 2.5V

3.3V

IN

> 3V

V

IN

+

10µF*

IN

LT1764A-2.5

SHDN

OUT

SENSE

GND

Regulator

OUT

1764 TA01

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2.5V

+

*TANTALUM,
CERAMIC OR
ALUMINUM ELECTROLYTIC

3A

10µF*

Dropout Voltage

400

350

300

250

200

150

100

DROPOUT VOLTAGE (mV)

50

0

0 0.5

1.0 2.01.5

LOAD CURRENT (A)

2.5

3.0

1764 TA02

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LT1764A Series

WW

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

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

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

Input to Output Differential Voltage (Note 12) ....... ±20V

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

ADJ Pin Voltage ...................................................... ±7V

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

U

W

PACKAGE/ORDER INFORMATION

FRONT VIEW

SENSE/ADJ*

5

OUT

TAB IS

GND

5-LEAD PLASTIC DD

*PIN 5 = SENSE FOR LT1764A-1.5/LT1764A-1.8/

LT1764A-2.5/LT1764A-3.3

= ADJ FOR LT1764A

T

JMAX

4

3

2

1

Q PACKAGE

= 150°C, θJA = 30°C/ W

GND

IN

SHDN

TAB IS

GND

*PIN 5 = SENSE FOR LT1764A-1.5/LT1764A-1.8/

FRONT VIEW

5

4

3

2

1

T PACKAGE

5-LEAD PLASTIC TO-220

LT1764A-2.5/LT1764A-3.3

= ADJ FOR LT1764A

= 150°C, θJA = 50°C/ W

T

JMAX

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

Operating Junction Temperature Range

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

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

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

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

U

TOP VIEW

1

SENSE/
ADJ*

OUT

GND

IN

SHDN

GND

OUT

OUT

OUT

SENSE/ADJ*

GND

GND

T

2

NC

3

4

17

5

6

7

8

FE PACKAGE

16-LEAD PLASTIC TSSOP

PIN 17 IS GND

= 150°C, θJA = 38°C/ W

JMAX

GND

16

NC

15

IN

14

*PIN 6 = SENSE FOR LT1764A-1.5/

IN

13

IN

12

NC

11

SHDN

10

GND

9

LT1764A-1.8/LT1764A-2.5/
LT1764A-3.3

= ADJ FOR LT1764A

ORDER PART NUMBER

LT1764AEQ
LT1764AEQ-1.5
LT1764AEQ-1.8
LT1764AEQ-2.5
LT1764AEQ-3.3

ORDER PART NUMBER

LT1764AET
LT1764AET-1.5
LT1764AET-1.8
LT1764AET-2.5
LT1764AET-3.3

ORDER PART NUMBER FE PART MARKING

LT1764AEFE
LT1764AEFE-1.5
LT1764AEFE-1.8
LT1764AEFE-2.5
LT1764AEFE-3.3

LT1764AEFE
LT1764AEFE-1.5
LT1764AEFE-1.8
LT1764AEFE-2.5
LT1764AEFE-3.3

LT1764AMPQ

Order Options

Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/

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

Tape and Reel: Add #TR

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Input Voltage I
(Notes 3, 11) I

Regulated Output Voltage LT1764A-1.5 VIN = 2.21V, I
(Note 4) 2.7V < V

= 0.5A 1.7 V

LOAD

= 1.5A 1.9 V

LOAD

E Grade: I
MP Grade: I

LT1764A-1.8 VIN = 2.3V, I

LOAD

LOAD

= 3A

= 3A

2.8V < V

●

●

= 1mA 1.477 1.500 1.523 V

LOAD

< 20V, 1mA < I

IN

= 1mA 1.773 1.800 1.827 V

LOAD

< 20V, 1mA < I

IN

LOAD

LOAD

< 3A

< 3A

●

1.447 1.500 1.545 V

●

1.737 1.800 1.854 V

2.3 2.7 V

2.3 2.8 V

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LT1764A Series

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2)

PARAMETER CONDITIONS MIN TYP MAX UNITS

LT1764A-2.5 VIN = 3V, I

3.5V < V

LT1764A-3.3 VIN = 3.8V, I

4.3V < V

ADJ Pin Voltage LT1764A VIN = 2.21V, I
(Notes 3, 4) E Grade: 2.7V < V

MP Grade: 2.8V < V

Line Regulation LT1764A-1.5 ∆VIN = 2.21V to 20V, I

LT1764A-1.8 ∆V
LT1764A-2.5 ∆V
LT1764A-3.3 ∆V
LT1764A (Note 3) ∆V

Load Regulation LT1764A-1.5 VIN = 2.7V, ∆I

V

IN

LT1764A-1.8 VIN = 2.8V, ∆I

V

IN

LT1764A-2.5 VIN = 3.5V, ∆I

V

IN

LT1764A-3.3 VIN = 4.3V, ∆I

V

IN

LT1764A (Note 3) VIN = 2.7V, ∆I

E Grade: V
MP Grade: V

Dropout Voltage I

= V

V

IN

OUT(NOMINAL)

(Notes 5, 6, 11) I

GND Pin Current I

= V

V

IN

OUT(NOMINAL)

+ 1V I

(Notes 5, 7) I

Output Voltage Noise C

= 1mA 0.02 0.05 V

LOAD

I

= 1mA

LOAD

= 100mA 0.07 0.13 V

LOAD

I

= 100mA

LOAD

I

= 500mA 0.14 0.20 V

LOAD

I

= 500mA

LOAD

I

= 1.5A 0.25 0.33 V

LOAD

= 1.5A

I

LOAD

I

= 3A 0.34 0.45 V

LOAD

= 3A

I

LOAD

= 0mA

LOAD

= 1mA

LOAD

= 100mA

LOAD

I

= 500mA

LOAD

I

= 1.5A

LOAD

I

= 3A

LOAD

= 10µF, I

OUT

= 3A, BW = 10Hz to 100kHz 40 µV

LOAD

ADJ Pin Bias Current (Notes 3, 8) 310µA

Shutdown Threshold V

SHDN Pin Current V
(Note 9) V

Quiescent Current in Shutdown VIN = 6V, V

Ripple Rejection VIN – V

= Off to On

OUT

V

= On to Off

OUT

= 0V 0.01 1 µA

SHDN

= 20V 730µA

SHDN

= 0V 0.01 1 µA

SHDN

= 1.5V (Avg), V

OUT

f

= 120Hz, I

RIPPLE

LOAD

= 1mA 2.462 2.500 2.538 V

LOAD

< 20V, 1mA < I

IN

= 1mA 3.250 3.300 3.350 V

LOAD

< 20V, 1mA < I

IN

= 1mA 1.192 1.210 1.228 V

LOAD

< 20V, 1mA < I

IN

IN

= 2.3V to 20V, I

IN

= 3V to 20V, I

IN

= 3.8V to 20V, I

IN

= 2.21V to 20V, I

IN

IN

RIPPLE

LOAD
LOAD

LOAD
LOAD

LOAD
LOAD

LOAD
LOAD

LOAD

= 2.7V, ∆I

= 2.8V, ∆I

IN

= 0.5V

= 2.7V, ∆I

= 2.8V, ∆I

= 3.5V, ∆I

= 4.3V, ∆I

< 20V, 1mA < I

LOAD

LOAD

LOAD

LOAD

LOAD

LOAD

= 1mA

= 1mA

= 1mA

LOAD

< 3A

< 3A

LOAD

= 1mA

= 1mA

< 3A

LOAD

< 3A

●

2.412 2.500 2.575 V

●

3.183 3.300 3.400 V

●

1.168 1.210 1.246 V

●

1.168 1.210 1.246 V

●

●

●

●

●

2.5 10 mV
310mV
410mV

4.5 10 mV
210mV

= 1mA to 3A 3 7 mV
= 1mA to 3A

●

= 1mA to 3A 4 8 mV
= 1mA to 3A

●

= 1mA to 3A 4 10 mV
= 1mA to 3A

●

= 1mA to 3A 4 12 mV
= 1mA to 3A

●

= 1mA to 3A 2 5 mV

= 1mA to 3A

LOAD

= 1mA to 3A

LOAD

,5563dB

P-P

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

0.25 0.75 V

1 1.5 mA

1.1 1.6 mA

3.5 5 mA

11 18 mA
40 75 mA

120 200 mA

0.9 2 V

= 1.5A

23 mV

25 mV

30 mV

40 mV

20 mV
20 mV

0.10 V

0.18 V

0.27 V

0.40 V

0.66 V

RMS

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LT1764A Series

TEMPERATURE (°C)

–50

DROPOUT VOLTAGE (mV)

400

500

600

25 75

1764 G03

300

200

–25 0

50 100 125

100

0

IL = 3A

IL = 1.5A

IL = 0.5A

IL = 100mA

IL = 1mA

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Current Limit VIN = 7V, V

E Grade: LT1764A; LT1764A-1.5;

= 2.7V, ∆V

V

IN

MP Grade: LT1764A

= 2.8V, ∆V

V

IN

Input Reverse Leakage Current VIN = –20V, V
Reverse Output Current (Note 10) LT1764A-1.5 V

LT1764A-1.8 V
LT1764A-2.5 V
LT1764A-3.3 V
LT1764A (Note 3) V

Note 1:

Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.

Note 2: The LT1764A regulators are tested and specified under pulse load
conditions such that T

= 25°C; performance at –40°C and 125°C is assured by design,

T

A

≈ TA. The LT1764A (E grade) is 100% tested at

J

characterization and correlation with statistical process controls. The
LT1764A (MP grade) is 100% tested and guaranteed over the –55°C to
125°C temperature range.

Note 3: The LT1764A (adjustable version) is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.

Note 4. 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.

Note 5: To satisfy requirements for minimum input voltage, the LT1764A
(adjustable version) is tested and specified for these conditions with an
external resistor divider (two 4.12k resistors) for an output voltage of

= 0V 4 A

OUT

●

3.1 A

= – 0.1V

OUT

●

3.1 A

= – 0.1V

OUT

= 0V

OUT

= 1.5V, VIN < 1.5V 600 1200 µA

OUT

= 1.8V, VIN < 1.8V 600 1200 µA

OUT

= 2.5V, VIN < 2.5V 600 1200 µA

OUT

= 3.3V, VIN < 3.3V 600 1200 µA

OUT

= 1.21V, VIN < 1.21V 300 600 µA

OUT

●

1mA

2.42V. The external resistor divider will add a 300µA DC load on the output.
Note 6: 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

Note 7: GND pin current is tested with V

2.7V (E grade) or V

= 2.8V (MP grade), whichever is greater, and a current

IN

DROPOUT

= V

IN

OUT(NOMINAL)

.

+ 1V or VIN =

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

Note 8: ADJ pin bias current flows into the ADJ pin.
Note 9: SHDN pin current flows into the SHDN pin.
Note 10: 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 11. For the LT1764A, LT1764A-1.5 and LT1764A-1.8 dropout voltage
will be limited by the minimum input voltage specification under some
output voltage/load conditions.

Note 12. All combinations of absolute maximum input voltage and
absolute maximum output voltage cannot be achieved. The absolute
maximum differential from input to output is ±20V. For example, with

= 20V, V

V

IN

cannot be pulled below ground.

OUT

TYPICAL PERFOR A CE CHARACTERISTICS

Typical Dropout Voltage

600

500

400

300

200

DROPOUT VOLTAGE (mV)

100

0

4

0

TJ = 125°C

1.0 1.5 2.0

0.5
OUTPUT CURRENT (A)

TJ = 25°C

2.5 3.0

1764 G01

UW

Guaranteed Dropout Voltage

700

= TEST POINTS

600

500

400

300

200

100

GUARANTEED DROPOUT VOLTAGE (mV)

0

0

0.5 1.0
OUTPUT CURRENT (A)

TJ ≤ 125°C

TJ ≤ 25°C

1.5 2.5

Dropout Voltage

2.0 3.0

1764 G02

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TEMPERATURE (°C)

–50

OUTPUT VOLTAGE (V)

25

1756 G05

–25 0 50

1.84

1.83

1.82

1.81

1.80

1.79

1.78

1.77

1.76
75 100 125

IL = 1mA

TEMPERATURE (°C)

–50

ADJ PIN VOLTAGE (V)

25

1756 G08

–25 0 50

1.230

1.225

1.220

1.215

1.210

1.205

1.200

1.195

1.190
75 100 125

IL = 1mA

INPUT VOLTAGE (V)

0

QUIESCENT CURRENT (mA)

40

35

30

25

20

15

10

5

0

8

1764 G10

246 107135 9

TJ = 25°C
R

L

=

∞

V

SHDN

= V

IN

TYPICAL PERFOR A CE CHARACTERISTICS

LT1764A Series

Quiescent Current LT1764A-1.8 Output Voltage

1.4

LT1764A-1.5/1.8/2.5/3.3

1.2

1.0

0.8

0.6

0.4
VIN = 6V

QUIESCENT CURRENT (mA)

0.2

0

–50

=

R

L

IL = 0
V

SHDN

–25 0

∞

= V

IN

TEMPERATURE (°C)

25 75

LT1764A

50 100 125

1764 G04

LT1764A-2.5 Output Voltage

2.58
IL = 1mA

2.56

2.54

2.52

2.50

2.48

OUTPUT VOLTAGE (V)

2.46

2.44

2.42

–25 0 50

–50

25

TEMPERATURE (°C)

75 100 125

1756 G06

LT1764A-1.5 Output Voltage

1.54
IL = 1mA

1.53

1.52

1.51

1.50

1.49

OUTPUT VOLTAGE (V)

1.48

1.47

1.46

–25 0 50

–50

25

TEMPERATURE (°C)

75 100 125

1764A G40

LT1764A-3.3 Output Voltage LT1764A ADJ Pin Voltage

3.38
IL = 1mA

3.36

3.34

3.32

3.30

3.28

OUTPUT VOLTAGE (V)

3.26

3.24

3.22

–25 0 50

–50

25

TEMPERATURE (°C)

75 100 125

1756 G07

LT1764A-1.5 Quiescent Current

40

TJ = 25°C
R

35

V

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

0

0

= ∞

L

= V

SHDN

IN

246 107135 9

INPUT VOLTAGE (V)

LT1764A-1.8 Quiescent Current

40

TJ = 25°C

=

∞

R

35

L

V

= V

SHDN

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

8

1764 G41

0

0

IN

246 107135 9

INPUT VOLTAGE (V)

8

1764 G09

LT1764A-2.5 Quiescent Current

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LT1764A Series

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LT1764A-3.3 Quiescent Current LT1764A Quiescent Current

40

35

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

0

246 107135 9

0

INPUT VOLTAGE (V)

LT1764A-1.8 GND Pin Current

20.0

17.5

15.0

12.5

10.0

7.5

GND PIN CURRENT (mA)

5.0

2.5

0

RL = 3.6Ω

= 500mA*

I

L

RL = 18Ω
= 100mA*

I

L

3578246 10

10

INPUT VOLTAGE (V)

TJ = 25°C
R
V

TJ = 25°C
V

SHDN

*FOR V

RL = 6Ω
I

= 300mA*

L

L
SHDN

= V

OUT

=

8

∞

= V

1764 G11

IN

= 1.8V

9

1764 G13

IN

1.6
TJ = 25°C

= 4.3k

R

1.4

L

= V

V

SHDN

IN

1.2

1.0

0.8

0.6

0.4

QUIESCENT CURRENT (mA)

0.2

0

4 8 12 20142 6 10 18

0

INPUT VOLTAGE (V)

LT1764A-2.5 GND Pin Current LT1764A-3.3 GND Pin Current

40

35

30

25

20

15

GND PIN CURRENT (mA)

10

5

0

RL = 5Ω

= 500mA*

I

L

RL = 25Ω

= 100mA*

I

L

3578246 10

10

INPUT VOLTAGE (V)

TJ = 25°C

= V

V

SHDN

*FOR V

RL = 8.33Ω
I

L

16

1764 G12

IN

= 2.5V

OUT

= 300mA*

9

1764 G14

LT1764A-1.5 GND Pin Current

20.0
TJ = 25°C

= V

V

SHDN

17.5

15.0

12.5

10.0

7.5

GND PIN CURRENT (mA)

5.0

2.5

0

0

80

70

60

50

40

30

GND PIN CURRENT (mA)

20

10

0

IN

*FOR V

= 1.5V

OUT

RL = 3Ω

= 500mA*

I

L

RL = 15Ω
= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

RL = 6.6Ω

= 500mA*

I

L

10

3578246 10
INPUT VOLTAGE (V)

RL = 11Ω
I

RL = 5Ω

= 300mA*

I

L

TJ = 25°C
V

SHDN

*FOR V

= 300mA*

L

RL = 33Ω
I

8

= V

IN

= 3.3V

OUT

= 100mA*

L

1764 G42

9

1764 G15

LT1764A GND Pin Current LT1764A-1.8 GND Pin Current

15

TJ = 25°C

= V

V

SHDN

IN

*FOR V

12

9

6

GND PIN CURRENT (mA)

3

0

0

= 1.21V

OUT

RL = 2.42Ω

= 500mA*

I

L

RL = 4.33Ω

= 300mA*

I

L

RL = 12.1Ω

= 100mA*

I

L

2

3

19

6

7

8

4

5

10

INPUT VOLTAGE (V)

1764 G16

LT1764A-1.5 GND Pin Current

150

120

90

60

GND PIN CURRENT (mA)

30

0

123

0

RL = 0.5Ω

= 3A*

I

L

RL = 1Ω

= 1.5A*

I

L

45

INPUT VOLTAGE (V)

TJ = 25°C

= V

V

SHDN

IN

*FOR V

OUT

= 1.5V

RL = 2.14Ω

= 0.7A*

I

L

67 9

8

1764A G43

150

120

RL = 0.6Ω

= 3A*

90

60

GND PIN CURRENT (mA)

30

10

0

0

I

L

RL = 1.2Ω

= 1.5A*

I

L

2

3

19

4

5

INPUT VOLTAGE (V)

6

TJ = 25°C
V

SHDN

*FOR V

RL = 2.57Ω
I

L

6

7

= V

IN

= 1.8V

OUT

= 0.7A*

8

10

1764 G17

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