ANALOG DEVICES LT 1764 AEQ Datasheet

FEATURES

LT1764 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

■

Reverse Battery Protection

■

No Reverse Current

■

Thermal Limiting

■

Available in 5-Lead TO-220, DD and 16-Lead

(10Hz to 100kHz)

RMS

TSSOP Packages

U

APPLICATIO S

■

3.3V to 2.5V Logic Power Supply

■

Post Regulator for Switching Supplies

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, DD and Exposed Pad
16-lead TSSOP packages.

, 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 6144250, 6118263.

TYPICAL APPLICATIO

to 2.5V

3.3V

IN

IN

> 3V

V

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

1764fb

1

LT1764 Series

FE PACKAGE

16-LEAD PLASTIC TSSOP

EXPOSED PAD (PIN 17) IS GND. MUST BE

SOLDERED TO THE PCB.

1

2

3

4

5

6

7

8

TOP VIEW

16

15

14

13

12

11

10

9

GND

NC

OUT

OUT

OUT

SENSE/ADJ*

GND

GND

GND

NC

IN

IN

IN

NC

SHDN

GND

17

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

SENSE/ADJ*

5

OUT

TAB IS

GND

*PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/

LT1764-2.5/LT1764-3.3

= ADJ FOR LT1764

T

JMAX

4

3

2

1

Q PACKAGE

5-LEAD PLASTIC DD

= 150°C, θJA = 30°C/ W

GND

IN

SHDN

TAB IS

GND

*PIN 5 = SENSE FOR LT1764-1.5/LT1764-1.8/

FRONT VIEW

T PACKAGE

5-LEAD PLASTIC TO-220

LT1764-2.5/LT1764-3.3

= ADJ FOR LT1764

= 150°C, θJA = 50°C/ W

T

JMAX

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

5

4

3

2

1

SENSE/
ADJ*

OUT

GND

IN

SHDN

*PIN 6 = SENSE FOR LT1764-1.5/

LT1764-1.8/LT1764-2.5/
LT1764-3.3

= ADJ FOR LT1764

T

= 150°C, θJA = 38°C/ W

JMAX

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.

2

ORDER PART NUMBER

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

Tape and Reel: Add #TR

ORDER PART NUMBER

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

ORDER PART

NUMBER

LT1764EFE
LT1764EFE-1.5
LT1764EFE-1.8
LT1764EFE-2.5
LT1764EFE-3.3

FE PART

MARKING

1764EFE
1764EFE15
1764EFE18
1764EFE25
1764EFE33

1764fb

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

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

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

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

Dropout Voltage I
V

= V

IN

OUT(NOMINAL)

(Notes 5, 6, 11) I

= 0.5A 1.7 V

LOAD

= 1.5A 1.9 V

LOAD

I

= 2.7A, 110°C < TJ ≤ 125°C 2.3 2.7 V

LOAD

= 3A, –40°C ≤ TJ ≤ 110°C 2.3 2.7 V

I

LOAD

= 1mA 1.477 1.500 1.523 V

LOAD

< 20V, 1mA < I

IN

2.7V < V

LT1764-1.8 VIN = 2.3V, I

2.8V < V

2.8V < V

LT1764-2.5 VIN = 3V, I

3.5V < V

3.5V < V

LT1764-3.3 VIN = 3.8V, I

4.3V < V

4.3V < V

2.7V < V

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

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

= 1mA 0.02 0.05 V

LOAD

I

= 1mA

LOAD

= 100mA 0.07 0.13 V

LOAD

= 100mA

I

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

= 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

< 20V, 1mA < I

IN

LOAD

< 20V, 1mA < I

IN

< 20V, 1mA < I

IN

= 1mA 2.462 2.500 2.538 V

LOAD

< 20V, 1mA < I

IN

< 20V, 1mA < I

IN

LOAD

< 20V, 1mA < I

IN

< 20V, 1mA < I

IN

LOAD

< 20V, 1mA < I

IN

< 20V, 1mA < I

IN

= 2.3V to 20V, I

IN

= 3V to 20V, I

IN

= 3.8V to 20V, I

IN

= 2.21V to 20V, I

IN

V

= 2.7V, ∆I

IN

= 2.7V, ∆I

V

IN

V

= 2.8V, ∆I

IN

= 2.8V, ∆I

V

IN

V

= 3.5V, ∆I

IN

= 3.5V, ∆I

V

IN

V

= 4.3V, ∆I

IN

= 4.3V, ∆I

V

IN

V

= 2.7V, ∆I

IN

V

= 2.7V, ∆I

IN

= 1mA 1.773 1.800 1.827 V

= 1mA 3.250 3.300 3.350 V

= 1mA 1.192 1.210 1.228 V

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

LOAD
LOAD
LOAD

< 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

LOAD

LOAD

LOAD

LOAD

= 1mA

= 1mA

= 1mA

LOAD

= 1mA

= 1mA

●

●

●

●

●

2.5 10 mV
310mV
410mV

4.5 10 mV
210mV

= 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

●

●

●

●

0.10 V

0.18 V

0.27 V

0.40 V

1764fb

3

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

GND Pin Current I

= V

V

IN

OUT(NOMINAL)

+ 1V I

(Notes 5, 7) I

Output Voltage Noise C

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

Current Limit VIN = 7V, V

Input Reverse Leakage Current VIN = –20V, V

Reverse Output Current (Note 10) LT1764-1.5 V

= 0mA

LOAD

= 1mA

LOAD

= 100mA

LOAD

I

= 500mA

LOAD

= 1.5A

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

= Off to On

OUT

= On to Off

V

OUT

= 0V 0.01 1 µA

SHDN

= 20V 7 30 µA

SHDN

OUT

= 120Hz, I

f

RIPPLE

= 3A, BW = 10Hz to 100kHz 40 µV

LOAD

= 0V 0.01 1 µA

SHDN

= 1.5V (Avg), V

= 1.5A

LOAD

= 0V 4 A

OUT

RIPPLE

= 0.5V

,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

0.9 2 V

LT1764-1.8, LT1764-2.5, LT1764-3.3

= V

V

IN

= V

V

IN

OUT(NOMINAL)
OUT(NOMINAL)

+ 1V, ∆V
+ 1V, ∆V

= – 0.1V, –40°C ≤ TJ ≤ 110°C 3.1 A

OUT

= – 0.1V, 110°C < TJ ≤ 125°C 2.8 A

OUT

LT1764, LT1764-1.5

= 2.7V, ∆V

V

IN

V

= 2.7V, ∆V

IN

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

= – 0.1V, –40°C ≤ TJ ≤ 110°C 3.1 A

OUT

= – 0.1V, 110°C < TJ ≤ 125°C 2.8 A

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

RMS

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 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.

4

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 V
V

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

IN

IN

– V

DROPOUT

= V

IN

.

OUT(NOMINAL)

+ 1V or

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
V

= 20V, V

IN

cannot be pulled below ground.

OUT

1764fb

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

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

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Typical Dropout Voltage Guaranteed Dropout Voltage Dropout Voltage

600

500

700

600

= TEST POINTS

LT1764 Series

400

300

200

DROPOUT VOLTAGE (mV)

100

0

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

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)

LT1764

50 100 125

25 75

1764 G04

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

25

TEMPERATURE (°C)

75 100 125

1756 G05

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

–50

–25 0 50

25

TEMPERATURE (°C)

75 100 125

1756 G07

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)

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

1764fb

5

LT1764 Series

UW

TYPICAL PERFOR A CE CHARACTERISTICS

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

40

TJ = 25°C

=

∞

R

35

L

V

= V

SHDN

IN

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

0

246 107135 9

0

8

INPUT VOLTAGE (V)

1764 G10

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

= 300mA*

I

L

OUT

IN

= 1.8V

9

1764 G13

40

35

30

25

20

15

10

QUIESCENT CURRENT (mA)

5

0

246 107135 9

0

INPUT VOLTAGE (V)

40

35

30

25

RL = 5Ω

= 500mA*

I

L

20

15

GND PIN CURRENT (mA)

10

5

0

3578246 10

10

INPUT VOLTAGE (V)

RL = 25Ω

= 100mA*

I

L

= 25°C

T

J

V

SHDN

*FOR V

TJ = 25°C

=

∞

R

L

V

= V

SHDN

8

1764 G11

= V

IN

= 2.5V

OUT

RL = 8.33Ω

= 300mA*

I

L

9

1764 G14

1.6
TJ = 25°C

= 4.3k

R

1.4

L

= V

IN

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)

80

70

60

50

40

RL = 6.6Ω

= 500mA*

I

L

30

GND PIN CURRENT (mA)

20

10

0

3578246 10

10

INPUT VOLTAGE (V)

TJ = 25°C
V

SHDN

*FOR V

RL = 11Ω

= 300mA*

I

L

16

= V

IN

= 3.3V

OUT

RL = 33Ω

= 100mA*

I

L

1764 G12

9

1764 G15

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

0

0

L

2

3

19

INPUT VOLTAGE (V)

RL = 4.33Ω

= 300mA*

I

L

4

5

RL = 2.42Ω

= 500mA*

I

L

6

7

150

120

RL = 0.6Ω

= 3A*

90

60

GND PIN CURRENT (mA)

30

8

10

0

0

I

L

RL = 1.2Ω
I

2

3

19

= 1.5A*

L

4

5

TJ = 25°C

= V

V

SHDN

*FOR V

RL = 2.57Ω
I

L

6

7

IN

= 1.8V

OUT

= 0.7A*

8

10

INPUT VOLTAGE (V)

1764 G16

1764 G17

200

160

120

80

RL = 1.66Ω

= 1.5A*

GND PIN CURRENT (mA)

40

0

19

0

I

L

2

3

4

INPUT VOLTAGE (V)

6

TJ = 25°C
V

SHDN

*FOR V

RL = 0.83Ω

= 3A*

I

L

6

5

= V

IN

= 2.5V

OUT

RL = 3.57Ω

= 0.7A*

I

L

7

8

10

1764 G18

1764fb

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

TYPICAL PERFOR A CE CHARACTERISTICS

LT1764 Series

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)

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

0

–25

TEMPERATURE (°C)

RL = 1.1Ω

= 3A*

I

L

RL = 2.2Ω

= 1.5A*

I

L

4

5

25

TJ = 25°C
V

SHDN

*FOR V

6

50

= V

IN

OUT

RL = 4.71Ω

= 0.7A*

I

L

7

8

75

= 3.3V

1764 G19

100

1764 G22

10

125

150

120

90

60

GND PIN CURRENT (mA)

30

0

0

19

RL = 0.4Ω

I

RL = 0.81Ω

= 1.5A*

I

L

2

3

INPUT VOLTAGE (V)

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)

= 3A*

L

4

25

5

50

TJ = 25°C

= V

V

SHDN

*FOR V

RL = 1.73Ω
I

6

7

75

IN

= 1.21V

OUT

= 0.7A*

L

8

100

1764 G20

1764 G23

125

160

VIN = V

140

120

100

80

60

GND PIN CURRENT (mA)

40

20

10

0

OUT(NOM)

0.5 1.0 2.0

0

SHDN Pin Input Current

10

9

8

7

6

5

4

3

2

SHDN PIN INPUT CURRENT (µA)

1

0

4

0

218

SHDN PIN VOLTAGE (V)

LOAD

+ 1V

1.5

OUTPUT CURRENT (A)

6

12

8

14

10

2.5

3.0

1764 G21

16

20

1764 G24

10

SHDN PIN INPUT CURRENT (µA)

SHDN Pin Input Current ADJ Pin Bias Current Current Limit

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

9

8

7

6

5

4

3

2

1

0

–50

V

SHDN

–25

= 20V

0

50

25

TEMPERATURE (°C)

100

125

1764 G25

75

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7

LT1764 Series

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Current Limit 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
V

= 0V

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

TJ = 25°C

= 0V

V

= V

7

ADJ

V

IN

(LT1764)

= VFB

OUT

8

1764 G29

10

CURRENT FLOWS

INTO OUTPUT PIN

V

OUT

0

2

0

19

(LT1764-1.8/-2.5/-3.3)

3

OUTPUT VOLTAGE (V)

6

4

5

Reverse Output Current

1.0
VIN = 0V

0.9

= 1.21V (LT1764)

V

OUT

= 1.8V (LT1764-1.8)

V

OUT

0.8

= 2.5V (LT1764-2.5)

V

OUT

= 3.3V (LT1764-3.3)

V

OUT

0.7

0.6

0.5

0.4

0.3

0.2

REVERSE OUTPUT CURRENT (mA)

0.1

0

–50

–25

LT1764-1.8/-2.5/-3.3

LT1764

50

25

0

TEMPERATURE (°C)

100

125

1764 G30

75

Ripple Rejection

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)

Ripple Rejection LT1764 Minimum Input Voltage

75

70

65

60

RIPPLE REJECTION (dB)

55

IL = 1.5A

= V

V

IN

OUT(NOM)

RIPPLE

+ 0.5V

P-P

AT f = 120Hz

+ 1V

3.0

2.5

2.0

1.5

1.0

MINIMUM INPUT VOLTAGE (V)

0.5

I

= 500mA

L

C

= 100µF

OUT

TANTALUM +

10 × 1µF

CERAMIC

= 10µF

C

OUT

TANTALUM

100k

IL = 3A

IL = 1.5A

IL = 100mA

1764 G31

8

50

–50 –25

50

25

0

TEMPERATURE (°C)

0

–50

100

125

1764 G32

75

–25 0

TEMPERATURE (°C)

50 100 125

25 75

1764 G33

1764fb

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LT1764 Series

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

= 2.7V (LT1764)

V

IN

–25

= V

V

IN

OUT(NOM)

(LT1764-1.8/-2.5/-3.3)

–30

–25 0 50

–50

TEMPERATURE (°C)

LT1764-1.8

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

40

= 10µF

C

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

LT1764

1

LOAD CURRENT (A)

1764 G34

1764 G36

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)

LT1764-3.3 10Hz to 100kHz
Output Noise

V

OUT

100µV/

DIV

C

= 10µF 1ms/DIV 1764 G37

OUT

IL = 3A

1764 G35

LT1764-3.3 Transient Response

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

462

VIN = 4.3V

= 3.3µF TANTALUM

C

IN

C

OUT

8

10

TIME (µs)

= 10µF TANTALUM

12 14 18

16

1764 G38

LT1764-3.3 Transient Response

0.2

0.1

0

–0.1

DEVIATION (V)

OUTPUT VOLTAGE

–0.2

3

2

1

0

LOAD CURRENT (A)

20

0

462

VIN = 4.3V

= 33µF

C

IN

= 100µF TANTALUM

C

OUT

+ 10 × 1µF CERAMIC

12 14 18

8

10

TIME (µs)

16

20

1764 G39

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9

LT1764 Series

U

PI FU CTIO S

UU

(DD and TO-220/TSSOP)

SHDN (Pin 1/Pin 10): 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
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 several microamperes, and
the SHDN pin current, typically 7µA. If unused, the SHDN
pin must be connected to V

. The device will be in the low

IN

power shutdown state if the SHDN pin is not connected.

IN (Pin 2/Pins 12, 13, 14): 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/Pins 1, 7, 8, 9, 16, 17): Ground. The exposed
pad (FE Package) is ground and must be soldered to the
PCB for rated thermal performance.

OUT (Pin 4/Pins 3, 4, 5): 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/Pin 6): 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/Pin 6): 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.

10

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

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APPLICATIO S I FOR ATIO

LT1764 Series

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.

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

IN

V

IN

OUT

LT1764

ADJ

GND

Figure 2. Adjustable Operation

R2

R1

1764 F02

V

OUT

+

R

2

⎛

VV

=+

121 1

.

OUT ADJ

VV

=

121

.

ADJ

IA

=°

3

µ AT 25 C

ADJ

OUTPUT RANGE = 1.21V TO 20V

⎞

IR

+

⎜
⎝

()()

⎟
⎠

R

1

2

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. Ceramic capacitors are manufactured with a
variety of dielectrics, each with different behavior across
temperature and applied voltage. The most common di­electrics used are specified with EIA temperature charac­teristic codes of Z5U, Y5V, X5R and X7R. The Z5U and Y5V
dielectrics are good for providing high capacitances in a
small package, but they tend to have strong voltage and
temperature coefficients as shown in Figures 3 and 4.
When used with a 5V regulator, a 16V 10µF Y5V capacitor
can exhibit an effective value as low as 1µF to 2µF for the
DC bias voltage applied and 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. Care still must be exercised
when using X5R and X7R capacitors; the X5R and X7R
codes only specify operating temperature range and maxi­mum capacitance change over temperature. Capacitance
change due to DC bias with X5R and X7R capacitors is
better than Y5V and Z5U capacitors, but can still be
significant enough to drop capacitor values below appro­priate levels. Capacitor DC bias characteristics tend to
improve as component case size increases, but expected
capacitance at operating voltage should be verified.

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APPLICATIO S I FOR ATIO

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

12

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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:

)(VIN).

(I

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 tables list 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

)(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

Table 2. FE Package, 16-Lead TSSOP

COPPER AREA

TOPSIDE* BACKSIDE

2500mm22500mm22500mm

1000mm22500mm22500mm

2

225mm

100mm

* Device is mounted on topside

T Package, 5-Lead TO-220

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

2500mm22500mm

2

2500mm22500mm

BOARD AREA (JUNCTION-TO-AMBIENT)

THERMAL RESISTANCE

2

2

2

2

38°C/W

43°C/W

48°C/W

60°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

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APPLICATIONS INFORMATION

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
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.

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
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.

14

5.0

4.5
LT1764

4.0

3.5
LT1764-1.8

3.0

2.5

2.0

1.5

1.0

REVERSE OUTPUT CURRENT (mA)

0.5

0

012345678910

Figure 5. Reverse Output Current

OUTPUT VOLTAGE (V)

LT1764-2.5

LT1764-3.3

T

= 25°C

J

V

= OV

IN

CURRENT FLOWS INTO
OUTPUT PIN
V

= V

OUT

ADJ

V

= VFB (LT1764-1.8,

OUT

LT1764-2.5, LT1764-3.3)

1764 F05

(LT1764)

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TYPICAL APPLICATIO S

SCR Preregulator Provides Efficiency Over Line Variations

LT1764 Series

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

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15

LT1764 Series

U

TYPICAL APPLICATIO S

+

V

> 2.7V

IN

C1
10µF

ADJUST R1 FOR 0A TO 3A

Adjustable Current Source

R1

LT1004-1.2

CONSTANT CURRENT

1k

R2

40.2k

R3
2k

R5

0.01Ω

R4

2.2k

C2

3.3µF

R6

2.2k

–

2

1/2 LT1366

+

3

IN

LT1764-1.8

SHDN

GND

C3

1µF

8

4

1764 TA04

OUT

FB

R7
470Ω

1

LOAD

R8
100k

16

1764fb

PACKAGE DESCRIPTION

LT1764 Series

U

Q Package

5-Lead Plastic DD Pak

(LTC DWG # 05-08-1461)

.256

(6.502)

.060

(1.524)

.300

(7.620)

BOTTOM VIEW OF DD PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

(1.524)

(1.905)

.060

.075

.183

(4.648)

.060

(1.524)

TYP

.330 – .370

(8.382 – 9.398)

+.012

.143

–.020

+0.305

3.632

()

–0.508

.420

.350

.028 – .038

(0.711 – 0.965)

.565

.390 – .415

(9.906 – 10.541)

15° TYP

.067

(1.702)

BSC

TYP

.080

.205

.165 – .180

(4.191 – 4.572)

.420
.276

.059

(1.499)

TYP

.013 – .023

(0.330 – 0.584)

.325

.045 – .055

(1.143 – 1.397)

+.008

.004

–.004

+0.203

0.102

()

–0.102

.095 – .115

(2.413 – 2.921)

.050 ± .012

±

0.305)

(1.270

Q(DD5) 0502

.565

.067

RECOMMENDED SOLDER PAD LAYOUT

NOTE:

1. DIMENSIONS IN INCH/(MILLIMETER)

2. DRAWING NOT TO SCALE

.042

.090

.320

.090

.067

RECOMMENDED SOLDER PAD LAYOUT

FOR THICKER SOLDER PASTE APPLICATIONS

.042

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17

LT1764 Series

PACKAGE DESCRIPTION

U

T Package

5-Lead Plastic TO-220 (Standard)

(LTC DWG # 05-08-1421)

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

18

1764fb

PACKAGE DESCRIPTION

3.58

(.141)

U

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)

16 1514 13 12 11

LT1764 Series

10 9

6.60 ±0.10

4.50 ±0.10

RECOMMENDED SOLDER PAD LAYOUT

0.09 – 0.20

(.0035 – .0079)

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

2. DIMENSIONS ARE IN

3. DRAWING NOT TO SCALE

SEE NOTE 4

0.45 ±0.05

0.65 BSC

4.30 – 4.50*
(.169 – .177)

0.50 – 0.75

(.020 – .030)

MILLIMETERS

(INCHES)

2.94

(.116)

1.05 ±0.10

1345678

2

0.25
REF

0° – 8°

0.65

(.0256)

BSC

0.195 – 0.30

(.0077 – .0118)

TYP

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

2.94

(.116)

1.10

(.0433)

MAX

0.05 – 0.15

(.002 – .006)

FE16 (BB) TSSOP 0204

6.40

(.252)

BSC

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.

1764fb

19

LT1764 Series

TYPICAL APPLICATIO

V

> 3.7V

IN

U

Paralleling of Regulators for Higher Output Current

R1

+

SHDN

C1
100µF

R2

0.01Ω

R3

2.2k

0.01Ω

2.2k

R4

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

LT1121 150mA Micropower Low Dropout Regulator 30µA IQ, SOT-223 Package

LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current

LT1175 500mA Negative Low Dropout Micropower Regulator 45µA IQ, 0.26V Dropout Voltage, SOT-223 Package
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Q

LT1573 UltraFastTM Transient Response Low Dropout Regulator Drives External PNP

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LT1761 Series 100mA, Low Noise, Low Dropout Micropower Regulators in SOT-23 20µA Quiescent Current, 20µV

LT1762 Series 150mA, Low Noise, LDO Micropower Regulators 25µA Quiescent Current, 20µV

LT1763 Series 500mA, Low Noise, LDO Micropower Regulators 30µA Quiescent Current, 20µV

LT1962 300mA, Low Noise, LDO Micropower Regulator 20µV

LT1963 1.5A, Low Noise, Fast Transient Response LDO 40µV

UltraFast is a trademark of Linear Technology Corporation.
OPTI-LOOP is a registered trademark 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

20

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

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LT 1205 REV B • PRINTED IN USA

© LINEAR TECHNOLOGY CORPORATION 2005