Datasheet LT1764 Datasheet (LINEAR TECHNOLOGY)

查询LT1764-1.5供应商

FEATURES

■

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

■

Reverse Battery Protection

■

No Reverse Current

■

Thermal Limiting

(10Hz to 100kHz)

RMS

U

APPLICATIO S

■

3.3V to 2.5V Logic Power Supply

■

Post Regulator for Switching Supplies

LT1764 Series

3A, Fast Transient

Response, Low Noise,

LDO Regulators

U

DESCRIPTIO

The LT®1764 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 LT1764 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 LT1764
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 LT1764 regu­lators are available in 5-lead TO-220 and DD packages.

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

TYPICAL APPLICATIO

3.3VIN to 2.5V

IN

V

> 3V

IN

10µF

LT1764-2.5

SHDN

OUT

SENSE

GND

Regulator

OUT

U

Dropout Voltage

400

350

300

2.5V

++

3A

10µF

1764 TA01

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

1764fa

1

LT1764 Series

WW

W

ABSOLUTE MAXIMUM RATINGS

U

(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

U

W

PACKAGE/ORDER INFORMATION

FRONT VIEW

TAB IS

GND

Q PACKAGE

5-LEAD PLASTIC DD

*PIN 5 = SENSE FOR LT1764-1.8/

LT1764-2.5/LT1764-3.3

= ADJ FOR LT1764

T

= 150°C, θJA = 30°C/ W

JMAX

5
4
3
2
1

SENSE/ADJ*
OUT
GND
IN
SHDN

ORDER PART

NUMBER

LT1764EQ
LT1764EQ-1.5
LT1764EQ-1.8
LT1764EQ-2.5
LT1764EQ-3.3

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

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

Operating Junction Temperature Range –40°C to 125°C

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

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

U

TAB IS

GND

FRONT VIEW

5
4
3
2
1

T PACKAGE

5-LEAD PLASTIC TO-220

*PIN 5 = SENSE FOR LT1764-1.8/

LT1764-2.5/LT1764-3.3

= ADJ FOR LT1764

= 150°C, θJA = 50°C/W

T

JMAX

SENSE/ADJ*
OUT
GND
IN
SHDN

ORDER PART

NUMBER

LT1764ET
LT1764ET-1.5
LT1764ET-1.8
LT1764ET-2.5
LT1764ET-3.3

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

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 LT1764-1.5 VIN = 2.21V, I
(Note 4) 2.7V < V

ADJ Pin Voltage LT1764 VIN = 2.21V, I
(Notes 3, 4) 2.7V < V

= 0.5A 1.7 V

LOAD

= 1.5A 1.9 V

LOAD

= 2.7A, 110°C < TJ ≤ 125°C 2.3 2.7 V

I

LOAD

I

= 3A, –40°C ≤ TJ ≤ 110°C 2.3 2.7 V

LOAD

= 1mA 1.477 1.500 1.523 V

LOAD

IN

2.7V < V

IN

LT1764-1.8 VIN = 2.3V, I

2.8V < V

IN

2.8V < V

IN

LT1764-2.5 VIN = 3V, I

3.5V < V

IN

3.5V < V

IN

LT1764-3.3 VIN = 3.8V, I

4.3V < V

IN

4.3V < V

IN

IN

2.7V < V

IN

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

= 1mA 1.773 1.800 1.827 V

LOAD

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

= 1mA 2.462 2.500 2.538 V

LOAD

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

= 1mA 3.250 3.300 3.350 V

LOAD

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

= 1mA 1.192 1.210 1.228 V

LOAD

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

< 3A, –40°C ≤ TJ ≤ 110°C 1.447 1.500 1.545 V

LOAD

< 2.7A, 110°C < TJ ≤ 125°C 1.447 1.500 1.545 V

LOAD

< 3A, –40°C ≤ TJ ≤ 110°C 1.737 1.800 1.854 V

LOAD

< 2.7A, 110°C < TJ ≤ 125°C 1.737 1.800 1.854 V

LOAD

< 3A, –40°C ≤ TJ ≤ 110°C 2.412 2.500 2.575 V

LOAD

< 2.7A, 110°C < TJ ≤ 125°C 2.412 2.500 2.575 V

LOAD

< 3A, –40°C ≤ TJ ≤ 110°C 3.183 3.300 3.400 V

LOAD

< 2.7A, 110°C < TJ ≤ 125°C 3.183 3.300 3.400 V

LOAD

< 3A, –40°C ≤ TJ ≤ 110°C 1.168 1.210 1.246 V

LOAD

< 2.7A, 110°C < TJ ≤ 125°C 1.168 1.210 1.246 V

LOAD

2

1764fa

LT1764 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

Line Regulation LT1764-1.5 ∆VIN = 2.21V to 20V, I

LT1764-1.8 ∆V
LT1764-2.5 ∆V
LT1764-3.3 ∆V
LT1764 (Note 3) ∆V

Load Regulation LT1764-1.5 VIN = 2.7V, ∆I

LT1764-1.8 VIN = 2.8V, ∆I

LT1764-2.5 VIN = 3.5V, ∆I

LT1764-3.3 VIN = 4.3V, ∆I

LT1764 (Note 3) VIN = 2.7V, ∆I

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 ● 0.10 V

LOAD

= 100mA 0.07 0.13 V

LOAD

= 100mA ● 0.18 V

I

LOAD

I

= 500mA 0.14 0.20 V

LOAD

= 500mA ● 0.27 V

I

LOAD

I

= 1.5A 0.25 0.33 V

LOAD

I

= 1.5A ● 0.40 V

LOAD

I

= 2.7A, 110°C < TJ ≤ 125°C 0.66 V

LOAD

I

= 3A 0.34 0.45 V

LOAD

I

= 3A, –40°C ≤ TJ ≤ 110°C 0.66 V

LOAD

= 0mA ● 1 1.5 mA

LOAD

= 1mA ● 1.1 1.6 mA

LOAD

= 100mA ● 3.5 5 mA

LOAD

I

= 500mA ● 11 18 mA

LOAD

= 1.5A ● 40 75 mA

I

LOAD

= 2.7A, 110°C < TJ ≤ 125°C 120 200 mA

I

LOAD

I

= 3A, –40°C ≤ TJ ≤ 110°C 120 200 mA

LOAD

= 10µF, I

OUT

LOAD

= 2.3V to 20V, I

IN

= 3V to 20V, I

IN

= 3.8V to 20V, I

IN

= 2.21V to 20V, I

IN

= 2.7V, ∆I

V

IN

= 2.7V, ∆I

V

IN

= 2.8V, ∆I

V

IN

V

= 2.8V, ∆I

IN

= 3.5V, ∆I

V

IN

= 3.5V, ∆I

V

IN

V

= 4.3V, ∆I

IN

= 4.3V, ∆I

V

IN

= 2.7V, ∆I

V

IN

V

= 2.7V, ∆I

IN

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

= 3A, BW = 10Hz to 100kHz 40 µV

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 ● 0.9 2 V

OUT

V

= On to Off ● 0.25 0.75 V

OUT

= 0V 0.01 1 µA

SHDN

= 20V 730µA

SHDN

= 0V 0.01 1 µA

SHDN

f

RIPPLE

= 1.5V (Avg), V

OUT

= 120Hz, I

LOAD

= 1.5A

RIPPLE

= 0.5V

= 1mA ● 2.5 10 mV

LOAD

= 1mA ● 310mV

LOAD

= 1mA ● 410mV

LOAD

= 1mA ● 4.5 10 mV

LOAD

= 1mA ● 210mV

LOAD

= 1mA to 3A 3 7 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C23mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C23mV

= 1mA to 3A 4 8 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C25mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C25mV

= 1mA to 3A 4 10 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C30mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C30mV

= 1mA to 3A 4 12 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C40mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C40mV

= 1mA to 3A 2 5 mV
= 1mA to 3A, –40°C ≤ TJ ≤ 110°C20mV
= 1mA to 2.7A, 110°C < TJ ≤ 125°C20mV

RMS

,5563dB

P-P

1764fa

3

LT1764 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

LT1764-1.8, LT1764-2.5, LT1764-3.3
VIN = V

= V

V

IN

LT1764, LT1764-1.5

= 2.7V, ∆V

V

IN

= 2.7V, ∆V

V

IN

Input Reverse Leakage Current VIN = –20V, V
Reverse Output Current (Note 10) LT1764-1.5 V

LT1764-1.8 V
LT1764-2.5 V
LT1764-3.3 V
LT1764 (Note 3) V

= 0V 4 A

OUT

OUT(NOMINAL)
OUT(NOMINAL)

= –0.1V, –40°C ≤ TJ ≤ 110°C 3.1 A

OUT

= –0.1V, 110°C < TJ ≤ 125°C 2.8 A

OUT

= 0V ● 1mA

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

+ 1V, ∆V
+ 1V, ∆V

= 1.21V, VIN < 1.21V 300 600 µA

OUT

= –0.1V, –40°C ≤ TJ ≤ 110°C 3.1 A

OUT

= –0.1V, 110°C < TJ ≤ 125°C 2.8 A

OUT

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

Note 2: The LT1764 regulators are tested and specified under pulse load
conditions such that T

≈ TA. The LT1764 is 100% tested at TA = 25°C.

J

Performance at –40°C and 125°C is assured by design, characterization
and correlation with statistical process controls.

Note 3: The LT1764 (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 LT1764
(adjustable version) is tested and specified for these conditions with an
external resistor divider (two 4.12k resistors) for an output voltage of

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

Note 7: GND pin current is tested with VIN = V

= 2.7V (whichever is greater) and a current source load. The GND pin

V

IN

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 LT1764, LT1764-1.5 and LT1764-1.8 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
VIN = 20V, V

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Typical Dropout Voltage

600

500

Guaranteed Dropout Voltage

700

= TEST POINTS

600

– V

IN

DROPOUT

cannot be pulled below ground.

OUT

Dropout Voltage

.

OUT(NOMINAL)

+ 1V or

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

500

400

300

200

100

GUARANTEED DROPOUT VOLTAGE (mV)

0

0

TJ ≤ 125°C

TJ ≤ 25°C

0.5 1.0
OUTPUT CURRENT (A)

2.0 3.0

1.5 2.5

1764 G02

1764fa

LT1764 Series

TEMPERATURE (°C)

–50

OUTPUT VOLTAGE (V)

25

1756 G06

–25 0 50

2.58

2.56

2.54

2.52

2.50

2.48

2.46

2.44

2.42
75 100 125

IL = 1mA

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Quiescent Current LT1764-1.8 Output Voltage LT1764-2.5 Output Voltage

1.4

LT1764-1.8/2.5/3.3

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

LT1764

50 100 125

1764 G04

LT1764-3.3 Output Voltage LT1764 ADJ Pin Voltage LT1764-1.8 Quiescent Current

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

1.84
IL = 1mA

1.83

1.82

1.81

1.80

1.79

OUTPUT VOLTAGE (V)

1.78

1.77

1.76

–25 0 50

–50

1.230
IL = 1mA

1.225

1.220

1.215

1.210

1.205

ADJ PIN VOLTAGE (V)

1.200

1.195

1.190

–25 0 50

–50

25

TEMPERATURE (°C)

25

TEMPERATURE (°C)

75 100 125

1756 G05

75 100 125

1756 G08

40

TJ = 25°C

=

∞

R

35

L

V

= V

SHDN

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

0

0

IN

246 107135 9

INPUT VOLTAGE (V)

8

1764 G09

40

35

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

0

LT1764-2.5 Quiescent Current LT1764-3.3 Quiescent Current LT1764 Quiescent Current

TJ = 25°C
R

=

∞

L

V

= V

SHDN

IN

246 107135 9

0

INPUT VOLTAGE (V)

40

35

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

8

1764 G10

0

246 107135 9

0

INPUT VOLTAGE (V)

TJ = 25°C
R

=

∞

L

V

= V

SHDN

8

IN

1764 G11

1.6
TJ = 25°C
R

= 4.3k

1.4

L

= V

V

SHDN

1.2

1.0

0.8

0.6

0.4

QUIESCENT CURRENT (mA)

0.2

0

0

IN

4 8 12 20142 6 10 18

INPUT VOLTAGE (V)

16

1764 G12

1764fa

5

LT1764 Series

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LT1764-1.8 GND Pin Current LT1764-2.5 GND Pin Current LT1764-3.3 GND Pin Current

20.0

17.5

15.0

12.5

RL = 3.6Ω

I

= 500mA*

L

10.0

7.5

GND PIN CURRENT (mA)

5.0

2.5

0

RL = 18Ω

= 100mA*

I

L

3578246 10

10

INPUT VOLTAGE (V)

TJ = 25°C

= V

V

SHDN

*FOR V

RL = 6Ω
I

= 300mA*

L

OUT

IN

= 1.8V

9

1764 G13

40

35

30

25

RL = 5Ω
I

= 500mA*

L

20

15

GND PIN CURRENT (mA)

10

5

0

3578246 10

10

INPUT VOLTAGE (V)

RL = 25Ω

= 100mA*

I

L

TJ = 25°C
V

= V

SHDN

*FOR V

RL = 8.33Ω
I

L

IN

= 2.5V

OUT

= 300mA*

9

1764 G14

LT1764 GND Pin Current LT1764-1.8 GND Pin Current LT1764-2.5 GND Pin Current

15

TJ = 25°C

= V

V

SHDN

IN

*FOR V

12

OUT

= 1.21V

9

6

RL = 12.1Ω

= 100mA*

I

GND PIN CURRENT (mA)

3

L

RL = 2.42Ω

I

L

RL = 4.33Ω

= 300mA*

I

L

= 500mA*

150

120

RL = 0.6Ω

I

90

= 3A*

L

60

GND PIN CURRENT (mA)

30

RL = 1.2Ω
I

= 1.5A*

L

TJ = 25°C
V

= V

SHDN

*FOR V

RL = 2.57Ω
I

L

IN

= 1.8V

OUT

= 0.7A*

80

70

60

50

40

RL = 6.6Ω
I

L

30

GND PIN CURRENT (mA)

20

10

0

3578246 10

10

INPUT VOLTAGE (V)

200

160

120

80

GND PIN CURRENT (mA)

40

= 500mA*

RL = 1.66Ω

= 1.5A*

I

L

TJ = 25°C
V

SHDN

*FOR V

RL = 11Ω
I

= 300mA*

L

RL = 33Ω
I

TJ = 25°C
V

SHDN

*FOR V

RL = 0.83Ω

= 3A*

I

L

RL = 3.57Ω
I

L

= V

IN

= 3.3V

OUT

= 100mA*

L

= V

IN

= 2.5V

OUT

= 0.7A*

9

1764 G15

0

2

3

19

0

6

7

8

4

5

10

INPUT VOLTAGE (V)

1764 G16

0

2

3

19

0

6

7

8

4

5

10

0

INPUT VOLTAGE (V)

1764 G17

2

19

0

LT1764-3.3 GND Pin Current LT1764 GND Pin Current GND Pin Current vs I

200

160

120

80

GND PIN CURRENT (mA)

40

0

2

3

19

0

INPUT VOLTAGE (V)

RL = 1.1Ω

I

= 3A*

L

RL = 2.2Ω
I

= 1.5A*

L

4

5

TJ = 25°C
V

= V

SHDN

*FOR V

6

7

IN

= 3.3V

OUT

RL = 4.71Ω
I

= 0.7A*

L

8

1764 G19

10

150

120

90

60

GND PIN CURRENT (mA)

30

0

0

RL = 0.81Ω

I

= 1.5A*

L

2

3

19

INPUT VOLTAGE (V)

RL = 0.4Ω

I

= 3A*

L

4

5

TJ = 25°C
V

= V

SHDN

*FOR V

RL = 1.73Ω
I

6

7

IN

= 1.21V

OUT

= 0.7A*

L

8

1764 G20

160

VIN = V

OUT(NOM)

140

120

100

80

60

GND PIN CURRENT (mA)

40

20

0

0.5 1.0 2.0

10

0

OUTPUT CURRENT (A)

3

6

4

5

INPUT VOLTAGE (V)

LOAD

+ 1V

1.5

7

8

10

1764 G18

2.5

3.0

1764 G21

1764fa

6

UW

INPUT/OUTPUT DIFFERENTIAL (V)

0

CURRENT LIMIT (A)

2

4

6

1

3

5

4 8 12 16

1764 G27

2020 6 10 14 18

TJ = –50°C

TJ = 125°C

TJ = 25°C

TEMPERATURE (°C)

–50

0

REVERSE OUTPUT CURRENT (mA)

0.1

0.3

0.4

0.5

1.0

0.7

0

50

75

1764 G30

0.2

0.8

0.9

0.6

–25

25

100

125

VIN = 0V
V

OUT

= 1.21V (LT1764)

V

OUT

= 1.8V (LT1764-1.8)

V

OUT

= 2.5V (LT1764-2.5)

V

OUT

= 3.3V (LT1764-3.3)

LT1764-1.8/-2.5/-3.3

LT1764

TYPICAL PERFOR A CE CHARACTERISTICS

LT1764 Series

SHDN Pin Threshold
(On-to-Off)

1.0
IL = 1mA

0.9

0.8

0.7

0.6

0.5

0.4

0.3

SHDN PIN THRESHOLD (V)

0.2

0.1

0

–50

–25

0

TEMPERATURE (°C)

50

25

75

100

125

1764 G22

SHDN Pin Threshold
(Off-to-On)

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

SHDN PIN THRESHOLD (V)

0.2

0.1
0

–50

–25

IL = 3A

IL = 1mA

0

TEMPERATURE (°C)

SHDN Pin Input Current

10

9
8
7
6
5
4
3
2

SHDN PIN INPUT CURRENT (µA)

1
0

50

25

75

100

125

1764 G23

0

SHDN Pin Input Current ADJ Pin Bias Current Current Limit

10

V

= 20V

SHDN

9
8
7
6
5
4
3
2

SHDN PIN INPUT CURRENT (µA)

1
0

–50

–25

0

TEMPERATURE (°C)

50

25

75

100

125

1764 G25

4.0

3.5

3.0

2.5

2.0

1.5

1.0

ADJ PIN BIAS CURRENT (µA)

0.5

0

–25 0 50

–50

25

TEMPERATURE (°C)

75 100 125

1756 G26

4

6

218

SHDN PIN VOLTAGE (V)

12

14

16

8

10

20

1764 G24

Current Limit Reverse Output Current Reverse Output Current

6

5

4

3

2

CURRENT LIMIT (A)

1

0

–50

–25 0

50 100 125

25 75

TEMPERATURE (°C)

VIN = 7V

= 0V

V

OUT

1764 G28

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

REVERSE OUTPUT CURRENT (mA)

0.5

LT1764

LT1764-1.8

LT1764-2.5

LT1764-3.3

V

0

2

19

0

(LT1764-1.8/-2.5/-3.3)

3

4

5

OUTPUT VOLTAGE (V)

TJ = 25°C

V

CURRENT FLOWS

INTO OUTPUT PIN

= V

OUT

(LT1764)

ADJ

V

OUT

6

7

8

= 0V

IN

= VFB

1764 G29

10

1764fa

7

LT1764 Series

TEMPERATURE (°C)

–50

MINIMUM INPUT VOLTAGE (V)

2.0

2.5

3.0

25 75

1764 G33

1.5

1.0

–25 0

50 100 125

0.5

0

IL = 3A

IL = 1.5A

IL = 100mA

I

L

= 500mA

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Ripple Rejection Ripple Rejection LT1764 Minimum Input Voltage

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

IL = 1.5A

10

= V

V

IN

0

10 1k 10k 1M

OUT(NOM)

+ 50mV

100

+ 1V

RIPPLE

RMS

FREQUENCY (Hz)

C

OUT

TANTALUM +

10 × 1µF

CERAMIC

C

OUT

TANTALUM

Load Regulation

10

5

+ 1V

25

LT1764

LT1764-2.5

LT1764-3.3

75 100 125

0

–5

–10

–15

LOAD REGULATION (mV)

–20

∆IL = 1mA TO 3A
V

= 2.7V (LT1764)

IN

–25

= V

V

IN

OUT(NOM)

(LT1764-1.8/-2.5/-3.3)

–30

–25 0 50

–50

TEMPERATURE (°C)

LT1764-1.8

= 100µF

= 10µF

100k

1764 G31

1764 G34

75

70

65

60

RIPPLE REJECTION (dB)

55

50

–50 –25

0

TEMPERATURE (°C)

25

IL = 1.5A
V

IN

+ 0.5V
AT f = 120Hz

50

Output Noise Spectral Density

1

C

= 10µF

OUT

= 3A

I

LOAD

LT1764-3.3 LT1764-2.5

0.1

OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)

0.01
10

LT1764

100 1k 10k 100k

LT1764-1.8

FREQUENCY (Hz)

= V

OUT(NOM)

RIPPLE

P-P

75

100

+ 1V

1764 G32

1764 G35

125

RMS Output Noise vs Load Current
(10Hz to 100kHz)

40

C

= 10µF

OUT

35

)

30

RMS

25

20

15

OUTPUT NOISE (µV

10

5

0

0.001

0.0001 0.01 0.1 10

LT1764-3.3

LT1764-2.5

LT1764-1.8

LOAD CURRENT (A)

LT1764

1

1764 G36

LT1764-3.3 10Hz to 100kHz
Output Noise LT1764-3.3 Transient Response

V

OUT

100µV/DIV

C

OUT

8

IL = 3A

= 10µF 1ms/DIV 1764 G37

0.2

0.1
0

–0.1

DEVIATION (V)

OUTPUT VOLTAGE

–0.2

1.00

0.75

0.50

0.25

LOAD CURRENT (A)

0

0

LT1764-3.3 Transient Response

0.2

0.1
0

VIN = 4.3V

= 3.3µF TANTALUM

C

IN

= 10µF TANTALUM

C

OUT

462

8

10

TIME (µs)

12 14 18

16

20

1764 G38

–0.1

DEVIATION (V)

OUTPUT VOLTAGE

–0.2

3
2
1
0

LOAD CURRENT (A)

0

462

VIN = 4.3V
C

= 33µF

IN

C

= 100µF TANTALUM

OUT

+ 10 × 1µF CERAMIC

12 14 18

8

10

TIME (µs)

16

20

1764 G39

1764fa

LT1764 Series

U

UU

PI FU CTIO S

SHDN (Pin 1): Shutdown. The SHDN pin is used to put the
LT1764 regulators into a low power shutdown state. The
output will be off when the SHDN pin is pulled low. The
SHDN pin can be driven either by 5V logic or open­collector logic with a pull-up resistor. The pull-up resistor
is required to supply the pull-up current of the open­collector gate, normally several microamperes, and the
SHDN pin current, typically 7µA. If unused, the SHDN pin
must be connected to VIN. The device will be in the low
power shutdown state if the SHDN pin is not connected.

IN (Pin 2): 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
LT1764 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.

GND (Pin 3): Ground.

OUT (Pin 4): 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.

SENSE (Pin 5): Sense. For fixed voltage versions of the
LT1764 (LT1764-1.8/LT1764-2.5/LT1764-3.3), 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 critical
applications, small voltage drops are caused by the resis­tance (RP) of PC traces between the regulator and the 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 (Pin 5): Adjust. For the adjustable LT1764, this is the
input to the error amplifier. This pin is internally clamped
to ±7V. 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.

R

P

2

IN

LT1764

1

V

+

IN

Figure 1. Kelvin Sense Connection

SHDN

GND

OUT

SENSE

3

4

+

5

R

P

LOAD

1764 F01

1764fa

9

LT1764 Series

WUUU

APPLICATIO S I FOR ATIO

The LT1764 series are 3A low dropout regulators opti­mized for fast transient response. The devices are capable
of supplying 3A at a dropout voltage of 340mV. The low
operating quiescent current (1mA) drops to less than 1µA
in shutdown. In addition to the low quiescent current, the
LT1764 regulators incorporate several protection features
which make them ideal for use in battery-powered sys­tems. 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 LT1764-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.

Adjustable Operation

The adjustable version of the LT1764 has an output
voltage 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 4.17k 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.

IN

V

IN

VV

OUT ADJ

VV

ADJ

IA

=°

ADJ

OUTPUT RANGE = 1.21V TO 20V

Figure 2. Adjustable Operation

OUT

LT1764

ADJ

GND

R

2



=+

121 1

.

=

121

.

3

µ AT 25 C



+









R

1

+

R2

R1

1764 F02

IR

2

()()

V

OUT

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 to

1.21V: V

/1.21V. For example, load regulation for an

OUT

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

= 1.21V. At V

OUT

= 5V, load regulation is:

OUT

(5V/1.21V)(–3mV) = –12.4mV

Output Capacitance and Transient Response

The LT1764 regulators are designed to be stable with a
wide range of output capacitors. The ESR of the output
capacitor affects stability, most notably with small capaci­tors. A minimum output capacitor of 10µF with an ESR in
the range of 50mΩ to 3Ω is recommended to prevent
oscillations. Larger values of output capacitance can de­crease the peak deviations and provide improved transient
response for larger load current changes. Bypass capaci­tors, used to decouple individual components powered by
the LT1764-X, will increase the effective output capacitor
value.

Extra consideration must be given to the use of ceramic
capacitors. In some applications the use of ceramic ca­pacitors with an ESR below 50mΩ can cause oscillations.
Please consult our Applications Engineering department
for help with any issues concerning the use of ceramic
output 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 X7R. The Z5U and
Y5V dielectrics are good for providing high capacitances
in a small package, but exhibit strong voltage and tem­perature coefficients as shown in Figures 3 and 4. 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 X7R dielectrics result in
more stable characteristics and are more suitable for use
as the output capacitor. The X7R type has better stability
across temperature, while the X5R is less expensive and
is available in higher values.

Voltage and temperature coefficients are not the only
sources of problems. Some ceramic capacitors have a
piezoelectric response. A piezoelectric device generates

1764fa

10

WUUU

APPLICATIO S I FOR ATIO

LT1764 Series

20

0

–20

–40

–60

CHANGE IN VALUE (%)

–80

–100

0

Figure 3. Ceramic Capacitor DC Bias Characteristics

40

20

0

–20

–40

–60

CHANGE IN VALUE (%)

–80

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

–100

–50

Figure 4. Ceramic Capacitor Temperature Characteristics

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

X5R

Y5V

26

4

–25 0

8

DC BIAS VOLTAGE (V)

25 75

TEMPERATURE (°C)

14

12

10

Y5V

50 100 125

16

1764 F03

X5R

1764 F04

voltage across its terminals due to mechanical stress,
similar to the way a piezoelectric accelerometer or micro­phone works. For a ceramic capacitor the stress can be
induced by vibrations in the system or thermal transients.

Overload Recovery

Like many IC power regulators, the LT1764-X has safe
operating 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 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 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 LT1764 series.

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

Output Voltage Noise

The LT1764 regulators have been designed to provide low
output voltage noise over the 10Hz to 100kHz bandwidth
while operating at full load. Output voltage noise is typi­cally 50nV√Hz over this frequency bandwidth for the
LT1764 (adjustable version). For higher output voltages
(generated by using a resistor divider), the output voltage
noise will be gained up accordingly. This results in RMS
noise over the 10Hz to 100kHz bandwidth of 15µV
the LT1764 increasing to 37µV

for the LT1764-3.3.

RMS

RMS

for

Higher values of output voltage noise may be measured
when care is not exercised with regards to circuit layout
and testing. Crosstalk from nearby traces can induce
unwanted noise onto the output of the LT1764-X. Power
supply ripple rejection must also be considered; the LT1764
regulators do not have unlimited power supply rejection
and will pass a small portion of the input noise through to
the output.

1764fa

11

LT1764 Series

U

WUU

APPLICATIONS INFORMATION

Thermal Considerations

The power handling capability of the device is limited by
the maximum rated junction temperature (125°C). The
power dissipated by the device is made up of two compo­nents:

1. Output current multiplied by the input/output voltage
differential: (I

2. GND pin current multiplied by the input voltage:
(I

)(VIN).

GND

The GND pin current can be found using the GND Pin
Current curves in the Typical Performance Characteris­tics. Power dissipation will be equal to the sum of the two
components listed above.

The LT1764 series regulators have internal thermal limit­ing designed to protect the device during overload condi­tions. For continuous normal conditions, the maximum
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 ambient.
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. Surface mount heatsinks and plated
through-holes can also be used to spread the heat gener­ated by power devices.

The following table lists thermal resistance for several
different board sizes and copper areas. All measurements
were taken in still air on 1/16" FR-4 board with one ounce
copper.

Table 1. Q Package, 5-Lead DD

COPPER AREA

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

2500mm22500mm
1000mm22500mm

125mm22500mm

*Device is mounted on topside.

T Package, 5-Lead TO-220

Thermal Resistance (Junction-to-Case) = 2.5°C/W

)(VIN – V

OUT

2

2

2

OUT

2500mm
2500mm
2500mm

), and

THERMAL RESISTANCE

2

2

2

23°C/W
25°C/W
33°C/W

Calculating Junction Temperature

Example: Given an output voltage of 3.3V, an input voltage
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?

The power dissipated by the device will be equal to:

I

OUT(MAX)(VIN(MAX)

– V

OUT

) + I

GND(VIN(MAX)

)

where,

I

OUT(MAX)

V

IN(MAX)

I

GND

at (I

= 500mA

= 6V

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

OUT

So,

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

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:

1.41W(28°C/W) = 39.5°C

The maximum junction temperature will then be equal to
the maximum junction temperature rise above ambient
plus the maximum ambient temperature or:

T

= 50°C + 39.5°C = 89.5°C

JMAX

Protection Features

The LT1764 regulators incorporate several protection
features which make them ideal for use in battery-powered
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.

Current limit protection and thermal overload protection
are intended to protect the device against current overload
conditions at the output of the device. For normal opera­tion, the junction temperature should not exceed 125°C.

The input of the device will withstand reverse voltages of
20V. Current flow into the device will be limited to less than
1mA and no negative voltage will appear at the output. The

12

1764fa

LT1764 Series

OUTPUT VOLTAGE (V)

012345678910

REVERSE OUTPUT CURRENT (mA)

1764 F05

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5
0

LT1764-2.5

LT1764-3.3

LT1764-1.8

LT1764

T

J

= 25°C

V

IN

= OV
CURRENT FLOWS INTO
OUTPUT PIN
V

OUT

= V

ADJ

(LT1764)

V

OUT

= VFB (LT1764-1.8,

LT1764-2.5, LT1764-3.3)

U

WUU

APPLICATIONS INFORMATION

device will protect both itself and the load. This provides
protection against batteries which can be plugged in
backward.

The output of the LT1764-X can be pulled below ground
without damaging the device. If the input is left open circuit
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.

The ADJ pin of the adjustable device can be pulled above
or below ground by as much as 7V without damaging the
device. If the input is left open circuit or grounded, the ADJ
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.

pins divided by the 5mA maximum current into the ADJ pin
yields a minimum top resistor value of 2.6k.

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 5.

When the IN pin of the LT1764-X is forced below the OUT
pin or the OUT pin is pulled above the IN pin, input current
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.

In situations where the ADJ pin is connected to a resistor
divider that would pull the ADJ pin above its 7V clamp
voltage 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 7V. The 13V difference between OUT and ADJ

Figure 5. Reverse Output Current

1764fa

13

LT1764 Series

TYPICAL APPLICATIO S

SCR Preregulator Provides Efficiency Over Line Variations

U

90V AC

TO 140V AC

ALL “V

POINTS

L2

10V AC
AT 115V

IN

10V AC
AT 115V

IN

1N4002 1N4002

“SYNC”

TO

+

”

L1: COILTRONICS CTX500-2-52
L2: STANCOR P-8560
*1% FILM RESISTOR

1N4002

+

22µF

NTE5437

NTE5437

2.4k

750Ω

1N4148

1k

+

1/2 LT1018

–

0.033µF

L1

500µH

C1A

+

V

750Ω

+

1/2 LT1018

10000µF

1N4148

C1B

LT1764-3.3

IN

OUT

SHDN

GND

34k*

12.1k*

+

V

200k

0.1µF

+

1N4148

–

10k

+

V

1µF

FB

V

LT1006

+

+

+

A1

–

22µF

10k

V

OUT

3.3V
3A

10k

LT1004

1.2V

1764 TA03

+

V

14

V

IN

> 2.7V

Adjustable Current Source

R5

0.01Ω

40.2k

R3
2k

R1

1k

R2

R4

2.2k

R6

2.2k

C2

3.3µF

+

C1
10µF

LT1004-1.2

ADJUST R1 FOR 0A TO 3A

CONSTANT CURRENT

IN

SHDN

–

2

1/2 LT1366

+

3

LT1764-1.8

GND

C3

1µF

8

4

1764 TA04

OUT

FB

R7
470Ω

1

LOAD

R8
100k

1764fa

PACKAGE DESCRIPTION

LT1764 Series

U

Q Package

5-Lead Plastic DD Pak

(LTC DWG # 05-08-1461)

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)

0.060

(1.524)

TYP

0.330 – 0.370

(8.382 – 9.398)

+0.012

0.143
–0.020

+0.305

3.632

()

–0.508

0.028 – 0.038

(0.711 – 0.965)

0.390 – 0.415

(9.906 – 10.541)

15

° TYP

0.067

(1.70)

BSC

T Package

5-Lead Plastic TO-220 (Standard)

(LTC DWG # 05-08-1421)

0.165 – 0.180

(4.191 – 4.572)

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)

Q(DD5) 1098

0.390 – 0.415

(9.906 – 10.541)

0.460 – 0.500

(11.684 – 12.700)

0.067

BSC

(1.70)

0.147 – 0.155

(3.734 – 3.937)

0.230 – 0.270

(5.842 – 6.858)

0.330 – 0.370

(8.382 – 9.398)

0.028 – 0.038

(0.711 – 0.965)

DIA

0.570 – 0.620

(14.478 – 15.748)

SEATING PLANE

0.260 – 0.320
(6.60 – 8.13)

0.700 – 0.728

(17.78 – 18.491)

0.152 – 0.202

(3.861 – 5.131)

0.135 – 0.165

(3.429 – 4.191)

0.165 – 0.180

(4.191 – 4.572)

0.620

(15.75)

TYP

0.045 – 0.055

(1.143 – 1.397)

0.095 – 0.115

(2.413 – 2.921)

0.155 – 0.195*

(3.937 – 4.953)

0.013 – 0.023

(0.330 – 0.584)

* MEASURED AT THE SEATING PLANE

T5 (TO-220) 0399

1764fa

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.

15

LT1764 Series

TYPICAL APPLICATIO

> 3.7V

V

IN

U

Paralleling of Regulators for Higher Output Current

R1

+

SHDN

C1
100µF

R2

0.01Ω

R3

2.2k

0.01Ω

R4

2.2k
3

+

2

–

8

1/2 LT1366

4

IN

LT1764-3.3

SHDN

GND

IN

LT1764

SHDN

GND

1

C3

0.01µF

OUT

FB

OUT

ADJ

R5
1k

1764 TA05

R6

6.65k

R7

4.12k

3.3V

C2
22µF

6A

+

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

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Q

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UltraFast and OPTI-LOOP are trademarks of Linear Technology Corporation.

Includes 2.5V Reference and Comparator

500mV Dropout Voltage

Noise, SOT-23 Package

RMS

Noise, MSOP Package

RMS

Noise, SO-8 Package

RMS

Noise, MSOP Package

RMS

Noise, SOT-223 Package

RMS

16

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

1764fa

LT/TP 0602 1.5K REV A • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2000