ANALOG DEVICES LT 1763 CS8-3.3 Datasheet

LT1763 Series

500mA, Low Noise, LDO

Micropower Regulators

FEATURES

n

Low Noise: 20μV

n

Output Current: 500mA

n

Low Quiescent Current: 30μA

n

Wide Input Voltage Range: 1.8V to 20V

n

Low Dropout Voltage: 300mV

n

Very Low Shutdown Current: < 1μA

n

No Protection Diodes Needed

n

Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3V, 3.3V, 5V

n

Adjustable Output from 1.22V to 20V

n

Stable with 3.3μF Output Capacitor

n

Stable with Aluminum, Tantalum or Ceramic

(10Hz to 100kHz)

RMS

Capacitors

n

Reverse Battery Protection

n

No Reverse Current

n

Overcurrent and Overtemperature Protected

n

8-Lead SO and 12-Lead (4mm × 3mm) DFN

Packages

APPLICATIONS

n

Cellular Phones

n

Battery-Powered Systems

n

Noise-Sensitive Instrumentation Systems

DESCRIPTION

The LT®1763 series are micropower, low noise, low dropout
regulators. The devices are capable of supplying 500mA of
output current with a dropout voltage of 300mV. Designed
for use in battery-powered systems, the low 30μA quiescent
current makes them an ideal choice. Quiescent current is
well controlled; it does not rise in dropout as it does with
many other regulators.

A key feature of the LT1763 regulators is low output noise.
With the addition of an external 0.01μF bypass capacitor,
output noise drops to 20μV
bandwidth. The LT1763 regulators are stable with output
capacitors as low as 3.3μF. Small ceramic capacitors can
be used without the series resistance required by other
regulators.

Internal protection circuitry includes reverse battery
protection, current limiting, thermal limiting and reverse
current protection. The parts come in fi xed output voltages
of 1.5V, 1.8V, 2.5V, 3V, 3.3V and 5V, and as an adjustable
device with a 1.22V reference voltage. The LT1763
regulators are available in 8-lead SO and 12-lead, low
profi le (4mm × 3mm × 0.75mm) DFN packages.

L, LT, LTC, LTM, Linear Technology and the Linear logo 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.

over a 10Hz to 100kHz

RMS

TYPICAL APPLICATION

3.3V Low Noise Regulator

V

3.7V TO
20V

IN

1μF

IN

SHDN

OUT

SENSE

LT1763-3.3

BYP

GND

0.01μF

+

1763 TA01

3.3V AT 500mA
20μV

RMS

10μF

NOISE

Dropout Voltage

400

350

300

250

200

150

100

DROPOUT VOLTAGE (mV)

50

0

100

0

OUTPUT CURRENT (mA)

200

300

400

500

1763 TA02

1763ff

1

LT1763 Series

ABSOLUTE MAXIMUM RATINGS

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

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

Input to Output Differential Voltage ........................ ±20V

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

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

BYP Pin Voltage .....................................................±0.6V

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

Output Short-Circuit Duration ........................ Indefi nite

PIN CONFIGURATION

TOP VIEW

NC

1

OUT

2

OUT

3

NC

SENSE/ADJ*

BYP

12-LEAD (4mm × 3mm) PLASTIC DFN

T

= 125°C, θJA = 40°C/W, θJC = 5°C/W

JMAX

EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB

*PIN 5: SENSE FOR LT1763-1.5/LT1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5

SEE THE APPLICATIONS INFORMATION SECTION.

13

4

GND

5

6

DE PACKAGE

ADJ FOR LT1763

NC

12

IN

11

IN

10

NC

9

SHDN

8

GND

7

(Note 1)

Operating Junction Temperature Range (Note 2)

C, I Grade ...........................................– 40°C to 125°C

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

Storage Temperature Range

S8 Package ........................................–65°C to 150°C

DFN Package ......................................–65°C to 150°C

Lead Temperature (Soldering, 10 sec)

S8 Package ....................................................... 300°C

TOP VIEW

OUT

1

SENSE/ADJ*

*PIN 2: SENSE FOR LT1763-1.5/LT1763-1.8/LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5

SEE THE APPLICATIONS INFORMATION SECTION.

2

GND

3

BYP

4

S8 PACKAGE

8-LEAD PLASTIC SO

T

= 150°C, θJA = 70°C/W, θJC = 35°C/W

JMAX

ADJ FOR LT1763

IN

8

GND

7

GND

6

SHDN

5

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1763CDE#PBF LT1763CDE#TRPBF 1763

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

LT1763IDE#PBF LT1763IDE#TRPBF 1763 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-1.5#PBF LT1763CDE-1.5#TRPBF 76315

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

LT1763IDE-1.5#PBF LT1763IDE-1.5#TRPBF 76315 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-1.8#PBF LT1763CDE-1.8#TRPBF 76318

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

LT1763IDE-1.8#PBF LT1763IDE-1.8#TRPBF 76318 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-2.5#PBF LT1763CDE-2.5#TRPBF 76325

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

LT1763IDE-2.5#PBF LT1763IDE-2.5#TRPBF 76325 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-3#PBF LT1763CDE-3#TRPBF 17633

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

LT1763IDE-3#PBF LT1763IDE-3#TRPBF 17633 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-3.3#PBF LT1763CDE-3.3#TRPBF 76333

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

LT1763IDE-3.3#PBF LT1763IDE-3.3#TRPBF 76333 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

1763ff

2

LT1763 Series

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1763CDE-5#PBF LT1763CDE-5#TRPBF 17635

LT1763IDE-5#PBF LT1763IDE-5#TRPBF 17635 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CS8#PBF LT1763CS8#TRPBF 1763 8-Lead Plastic SO –40°C to 125°C

LT1763IS8#PBF LT1763IS8#TRPBF 1763 8-Lead Plastic SO –40°C to 125°C

LT1763MPS8#PBF LT1763MPS8#TRPBF 1763MP 8-Lead Plastic SO –55°C to 125°C

LT1763CS8-1.5#PBF LT1763CS8-1.5#TRPBF 176315 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-1.5#PBF LT1763IS8-1.5#TRPBF 176315 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-1.8#PBF LT1763CS8-1.8#TRPBF 176318 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-1.8#PBF LT1763IS8-1.8#TRPBF 176318 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-2.5#PBF LT1763CS8-2.5#TRPBF 176325 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-2.5#PBF LT1763IS8-2.5#TRPBF 176325 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-3#PBF LT1763CS8-3#TRPBF 17633 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-3#PBF LT1763IS8-3#TRPBF 17633 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-3.3#PBF LT1763CS8-3.3#TRPBF 176333 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-3.3#PBF LT1763IS8-3.3#TRPBF 176333 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-5#PBF LT1763CS8-5#TRPBF 17635 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-5#PBF LT1763IS8-5#TRPBF 17635 8-Lead Plastic SO –40°C to 125°C

LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1763CDE LT1763CDE#TR 1763

LT1763IDE LT1763IDE#TR 1763 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-1.5 LT1763CDE-1.5#TR 76315

LT1763IDE-1.5 LT1763IDE-1.5#TR 76315 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-1.8 LT1763CDE-1.8#TR 76318

LT1763IDE-1.8 LT1763IDE-1.8#TR 76318 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-2.5 LT1763CDE-2.5#TR 76325

LT1763IDE-2.5 LT1763IDE-2.5#TR 76325 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-3 LT1763CDE-3#TR 17633

LT1763IDE-3 LT1763IDE-3#TR 17633 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-3.3 LT1763CDE-3.3#TR 76333

LT1763IDE-3.3 LT1763IDE-3.3#TR 76333 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CDE-5 LT1763CDE-5#TR 17635

LT1763IDE-5 LT1763IDE-5#TR 17635 12-Lead (4mm × 3mm) Plastic DFN –40°C to 125°C

LT1763CS8 LT1763CS8#TR 1763 8-Lead Plastic SO – 40°C to 125°C

LT1763IS8 LT1763IS8#TR 1763 8-Lead Plastic SO – 40°C to 125°C

LT1763MPS8 LT1763MPS8#TR 1763MP 8-Lead Plastic SO –55°C to 125°C

LT1763CS8-1.5 LT1763CS8-1.5#TR 176315 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-1.5 LT1763IS8-1.5#TR 176315 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-1.8 LT1763CS8-1.8#TR 176318 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-1.8 LT1763IS8-1.8#TR 176318 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-2.5 LT1763CS8-2.5#TR 176325 8-Lead Plastic SO –40°C to 125°C

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

12-Lead (4mm × 3mm) Plastic DFN

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

–40°C to 125°C

1763ff

3

LT1763 Series

ORDER INFORMATION

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1763IS8-2.5 LT1763IS8-2.5#TR 176325 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-3 LT1763CS8-3#TR 17633 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-3 LT1763IS8-3#TR 17633 8-Lead Plastic SO – 40°C to 125°C

LT1763CS8-3.3 LT1763CS8-3.3#TR 176333 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-3.3 LT1763IS8-3.3#TR 176333 8-Lead Plastic SO –40°C to 125°C

LT1763CS8-5 LT1763CS8-5#TR 17635 8-Lead Plastic SO –40°C to 125°C

LT1763IS8-5 LT1763IS8-5#TR 17635 8-Lead Plastic SO – 40°C to 125°C

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
For more information on lead free part marking, go to:

For more information on tape and reel specifi cations, go to:

ELECTRICAL CHARACTERISTICS

The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C. (Note 2)

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Operating Voltage C, I Grade: I

Regulated Output Voltage
(Note 4)

ADJ Pin Voltage
(Notes 3, 4)

Line Regulation LT1763-1.5 ΔV

MP Grade: I

LT1763-1.5 VIN = 2V, I

2.5V < V

LT1763-1.8 VIN = 2.3V, I

2.8V < V

LT1763-2.5 VIN = 3V, I

3.5V < V

LT1763-3 VIN = 3.5V, I
4V < V

LT1763-3.3 VIN = 3.8V, I

4.3V < V

LT1763-5 V
6V < V

LT1763 V
C, I Grade: 2.3V < V
MP Grade: 2.35V < V

LT1763-1.8 ΔV
LT1763-2.5 ΔVIN = 3V to 20V, I
LT1763-3 ΔV
LT1763-3.3 ΔV
LT1763-5 ΔVIN = 5.5V to 20V, I
LT1763 (Note 3) C, I Grade: ΔV
LT1763 (Note 3) MP Grade: ΔV

http://www.linear.com/leadfree/

http://www.linear.com/tapeandreel/

= 500mA (Notes 3, 11)

LOAD

= 500mA (Notes 3, 11)

LOAD

= 1mA

LOAD

< 20V, 1mA < I

IN

LOAD

< 20V, 1mA < I

IN

= 1mA

LOAD

< 20V, 1mA < I

IN

LOAD

< 20V, 1mA < I

IN

LOAD

< 20V, 1mA < I

IN

= 5.5V, I

IN

= 2.2V, I

IN

IN
IN

IN
IN

LOAD

< 20V, 1mA < I

IN

LOAD

= 2V to 20V, I
= 2.3V to 20V, I

= 3.5V to 20V, I
= 3.8V to 20V, I

IN
IN

LOAD

= 1mA

LOAD

LOAD

= 1mA

< 500mA

LOAD

= 1mA

LOAD

= 1mA

< 500mA

LOAD

= 1mA

< 20V, 1mA < I

IN

< 20V, 1mA < I

IN

= 1mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

= 2V to 20V, I
= 2.1V to 20V, I

< 500mA

< 500mA

< 500mA

< 500mA

LOAD

= 1mA

LOAD

= 1mA

LOAD

< 500mA

< 500mA

LOAD

l
l

1.485

l

1.462

1.782

l

1.755

2.475

l

2.435

2.970

l

2.925

3.267

l

3.220

4.950

l

4.875

1.208

l

1.190

l

1.190

l
l
l
l
l
l
l
l

1.8

1.8

1.5

1.5

1.8

1.8

2.5

2.5

3
3

3.3

3.3

5
5

1.220

1.220

1.220

1
1
1
1
1
1
1
1

2.3

2.35

1.515

1.538

1.818

1.845

2.525

2.565

3.030

3.075

3.333

3.380

5.050

5.125

1.232

1.250

1.250

5
5
5
5
5
5
5
5

mV
mV
mV
mV
mV
mV
mV
mV

V
V

V
V

V
V

V
V

V
V

V
V

V
V

V
V
V

4

1763ff

LT1763 Series

ELECTRICAL CHARACTERISTICS

The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T

PARAMETER CONDITIONS MIN TYP MAX UNITS

Load Regulation LT1763-1.5 V

Dropout Voltage
V

= V

IN

OUT(NOMINAL)

(Notes 5, 6, 11)

GND Pin Current
V

= V

IN

OUT(NOMINAL)

(Notes 5, 7)

Output Voltage Noise C

ADJ Pin Bias Current (Notes 3, 8) 30 100 nA

Shutdown Threshold V

SHDN Pin Current
(Note 9)

Quiescent Current in Shutdown V

Ripple Rejection V

Current Limit V

Input Reverse Leakage Current V

Reverse Output Current
(Note 10)

V

LT1763-1.8 V
V

LT1763-2.5 V
V

LT1763-3 V
V

LT1763-3.3 V
V

LT1763-5 V
V

LT1763 (Note 3) V
C, I Grade: V
MP Grade: V

= 10mA

I

LOAD

I

= 10mA

LOAD

I

= 50mA

LOAD

I

= 50mA

LOAD

I

= 100mA

LOAD

I

= 100mA

LOAD

I

= 500mA

LOAD

I

= 500mA

LOAD

= 0mA

I

LOAD

I

= 1mA

LOAD

I

= 50mA

LOAD

I

= 100mA

LOAD

I

= 250mA

LOAD

I

= 500mA

LOAD

= 10μF, C

OUT

= Off to On

OUT

V

= On to Off

OUT

V

SHDN

V

SHDN

= 6V, V

IN

– V

IN

I

= 500mA

LOAD

= 7V, V

IN

C, I Grade: V
MP Grade: V

= –20V, V

IN

BYP

= 0V
= 20V

= 0V 0.1 1 μA

SHDN

= 1.5V (Avg), V

OUT

= 0V

OUT

= V

IN

= 2.35V (Note 12), ΔV

IN

= 0V

OUT

LT1763-1.5 V
LT1763-1.8 V
LT1763-2.5 V
LT1763-3 V
LT1763-3.3 V
LT1763-5 V
LT1763 (Note 3) V

= 25°C. (Note 2)

A

= 2.5V, ΔI

IN

= 2.5V, ΔI

IN

= 2.8V, ΔI

IN

= 2.8V, ΔI

IN

= 3.5V, ΔI

IN

= 3.5V, ΔI

IN

= 4V, ΔI

IN
IN

IN
IN

IN
IN

IN

= 0.01μF, I

OUT(NOMINAL)

OUT
OUT
OUT
OUT
OUT
OUT
OUT

LOAD

= 4V, ΔI

LOAD

= 4.3V, ΔI
= 4.3V, ΔI

= 6V, ΔI

LOAD

= 6V, ΔI

LOAD

= 2.3V, ΔI

IN
IN

LOAD

RIPPLE

+ 1V or 2.3V (Note 12), ΔV

= 1.5V, VIN < 1.5V
= 1.8V, VIN < 1.8V
= 2.5V, VIN < 2.5V
= 3V, VIN < 3V
= 3.3V, VIN < 3.3V
= 5V, VIN < 5V
= 1.22V, VIN < 1.22V

= 1mA to 500mA

LOAD

= 1mA to 500mA

LOAD

= 1mA to 500mA

LOAD

= 1mA to 500mA

LOAD

= 1mA to 500mA

LOAD

= 1mA to 500mA

LOAD

= 1mA to 500mA
= 1mA to 500mA

= 1mA to 500mA

LOAD

= 1mA to 500mA

LOAD

= 1mA to 500mA
= 1mA to 500mA

= 1mA to 500mA

LOAD

= 2.3V, ΔI
= 2.35V, ΔI

LOAD

LOAD

= 1mA to 500mA

= 1mA to 500mA

l

l

l

l

l

l

l
l

3815mV

4918mV

51225mV

71530mV

71733mV

12 25

50

26

12
12

0.13 0.19

l

0.25

0.17 0.22

l

0.32

0.20 0.24

l

0.34

0.30 0.35

l

l
l
l
l
l
l

30
65

1.1
2
5

11

0.45

75

120

1.6
3
8

16

= 500mA, BW = 10Hz to 100kHz 20 μV

l
l

0.25

0.8

0.65

2V

0.1
1

= 0.5V

OUT

, f

P-P

RIPPLE

= –0.1V

= 120Hz,

OUT

= –0.1V

50 65 dB

l

520

l

520

l

10
10
10
10
10
10

5

1mA

20
20
20
20
20
20
10

mV

mV

mV

mV

mV

mV
mV

mV
mV
mV

μA

μA
mA
mA
mA
mA

RMS

μA

μA

mA
mA

μA

μA

μA

μA

μA

μA

μA

V
V

V
V

V
V

V
V

V

1763ff

5

LT1763 Series

ELECTRICAL CHARACTERISTICS

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 LT1763 regulators are tested and specifi ed under pulse
load conditions such that T
at T

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

A

≅ TA. The LT1763 (C grade) is 100% tested

J

characterization and correlation with statistical process controls. The
LT1763 (I grade) is guaranteed over the full – 40°C to 125°C operating
junction temperature range. The LT1763 (MP grade) is 100% tested and
guaranteed over the –55°C to 125°C operating junction temperature range.

Note 3: The LT1763 (adjustable version) is tested and specifi ed 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 specifi cation 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 LT1763
(adjustable version) is tested and specifi ed for these conditions with an
external resistor divider (two 250k resistors) for an output voltage of

2.44V. The external resistor divider will add a 5μA DC load on the output.

Note 6: Dropout voltage is the minimum input to output voltage differential
needed to maintain regulation at a specifi ed output current. In dropout, the
output voltage will be equal to: V

Note 7: GND pin current is tested with V

IN

– V

DROPOUT

= V

IN

.

OUT(NOMINAL)

or VIN = 2.3V
(C, I grade) or 2.35V (MP grade), whichever is greater, and a current
source load. This means the device is tested while operating in its dropout
region. This is the worst-case GND pin current. The GND pin current will
decrease slightly at higher input voltages.

Note 8: ADJ pin bias current fl ows into the ADJ pin.
Note 9: SHDN pin current fl ows 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 fl ows into the OUT
pin and out the GND pin.

Note 11: For the LT1763, LT1763-1.5 and LT1763-1.8 dropout voltage will
be limited by the minimum input voltage specifi cation under some output
voltage/load conditions. See the curve of Minimum Input Voltage in the
Typical Performance Characteristics.

Note 12: To satisfy requirements for minimum input voltage, current limit
is tested at V

= V

IN

OUT(NOMINAL)

+ 1V or 2.3V (C, I grade) or 2.35V

(MP grade), whichever is greater.

TYPICAL PERFORMANCE CHARACTERISTICS

Typical Dropout Voltage

500

450

400

350

300

250

200

150

DROPOUT VOLTAGE (mV)

100

50

0

0 50 100 150

OUTPUT CURRENT (mA)

TJ = 125°C

TJ = 25°C

200

300 350 400 450 500

250

1763 G01

Guaranteed Dropout Voltage

500

= TEST POINTS

450

400

350

300

250

200

150

100

50

GUARANTEED DROPOUT VOLTAGE (mV)

0

0 50 100 150

TJb 125°C

TJb 25°C

200

300 350 400 450 500

250

OUTPUT CURRENT (mA)

1763 G02

Dropout Voltage

500

450

400

350

IL = 100mA

300

250

200

150

DROPOUT VOLTAGE (mV)

100

50

0

–50

IL = 50mA

0

–25

TEMPERATURE (°C)

IL = 250mA

IL = 10mA

50

25

IL = 500mA

IL = 1mA

75

100

125

1763 G03

6

1763ff

TYPICAL PERFORMANCE CHARACTERISTICS

5

LT1763 Series

Quiescent Current

50

45

40

35

30

25

20

15

QUIESCENT CURRENT (μA)

10

5

0

V

= V

SHDN

IN

VIN = 6V

= d, IL = 0 (LT1763-1.5/-1.8/-2.5/-3/-3.3/-5)

R

L

= 250k, IL = 5μA (LT1763)

R

L

–50

050–25 25 75 125

TEMPERATURE (°C)

LT1763-2.5
Output Voltage

2.54
IL = 1mA

2.53

2.52

2.51

2.50

2.49

OUTPUT VOLTAGE (V)

2.48

2.47

2.46

–50

050

–25 25 75 125

TEMPERATURE (°C)

100

100

1763 G04

1763 G07

LT1763-1.5
Output Voltage

1.528
IL = 1mA

1.521

1.514

1.507

1.500

1.493

OUTPUT VOLTAGE (V)

1.486

1.479

1.472

–25 25 75 125

–50

LT1763-3
Output Voltage

3.060
IL = 1mA

3.045

3.030

3.015

3.000

2.985

OUTPUT VOLTAGE (V)

2.970

2.955

2.940

–25 25 75 125

–50

050

TEMPERATURE (°C)

050

TEMPERATURE (°C)

100

100

1763 G05

1763 G08

LT1763-1.8
Output Voltage

1.84
IL = 1mA

1.83

1.82

1.81

1.80

1.79

OUTPUT VOLTAGE (V)

1.78

1.77

1.76

–25 25 75 125

–50

LT1763-3.3
Output Voltage

3.360
IL = 1mA

3.345

3.330

3.315

3.300

3.285

OUTPUT VOLTAGE (V)

3.270

3.255

3.240

–25 25 75 125

–50

050

TEMPERATURE (°C)

050

TEMPERATURE (°C)

100

1763 G06

100

1763 G09

LT1763-5
Output Voltage

5.100
IL = 1mA

5.075

5.050

5.025

5.000

4.975

OUTPUT VOLTAGE (V)

4.950

4.925

4.900

–25 25 75 125

–50

050

TEMPERATURE (°C)

100

1763 G10

LT1763
ADJ Pin Voltage

1.240
IL = 1mA

1.235

1.230

1.225

1.220

1.215

ADJ PIN VOLTAGE (V)

1.210

1.205

1.200

–25 25 75 12

–50

050

TEMPERATURE (°C)

100

1763 G11

LT1763-1.5
Quiescent Current

250

225

200

175

150

125

100

75

QUIESCENT CURRENT (μA)

50

25

0

0

V

V

213579

INPUT VOLTAGE (V)

SHDN

SHDN

4

= V

= 0V

TJ = 25°C

= d

R

L

IN

6

8

10

1763 G12

1763ff

7

LT1763 Series

TYPICAL PERFORMANCE CHARACTERISTICS

LT1763-1.8
Quiescent Current

250

225

200

175

150

125

100

75

QUIESCENT CURRENT (μA)

50

25

0

213579

0

INPUT VOLTAGE (V)

LT1763-3.3
Quiescent Current

250

225

200

175

150

125

100

75

QUIESCENT CURRENT (μA)

50

25

0

213579

0

INPUT VOLTAGE (V)

4

4

V

V

SHDN

SHDN

= V

= 0V

6

V

V

6

IN

SHDN

SHDN

TJ = 25°C

= d

R

L

8

TJ = 25°C

= d

R

L

= V

IN

= 0V

8

1763 G13

1763 G16

250

225

200

175

150

125

100

75

QUIESCENT CURRENT (μA)

50

25

10

250

225

200

175

150

125

100

75

QUIESCENT CURRENT (μA)

50

25

10

LT1763-2.5
Quiescent Current

0

213579

0

INPUT VOLTAGE (V)

LT1763-5
Quiescent Current

0

213579

0

INPUT VOLTAGE (V)

LT1763-3
Quiescent Current

TJ = 25°C

= d

R

L

V

= V

SHDN

IN

V

= 0V

SHDN

6

8

4

10

1763 G14

250

225

200

175

150

125

100

75

QUIESCENT CURRENT (μA)

50

25

0

213579

0

INPUT VOLTAGE (V)

TJ = 25°C

= d

R

L

V

= V

SHDN

IN

V

= 0V

SHDN

6

8

4

10

1763 G15

LT1763
Quiescent Current

TJ = 25°C

= d

R

L

V

= V

SHDN

IN

V

= 0V

SHDN

6

8

4

10

1763 G17

40

TJ = 25°C

35

= 250k

R

L

30

25

20

15

10

QUIESCENT CURRENT (μA)

5

0

42 6 10 14 18

0

INPUT VOLTAGE (V)

V

= V

SHDN

IN

V

= 0V

SHDN

12

16

8

20

1763 G18

LT1763-1.5
GND Pin Current

1200

1000

800

600

400

GND PIN CURRENT (μA)

200

0

0123

8

RL = 30Ω

= 50mA*

I

L

RL = 150Ω

= 10mA*

I

L

RL = 1.5k

= 1mA*

I

L

4

INPUT VOLTAGE (V)

TJ = 25°C

= V

V

IN

SHDN

*FOR V

= 1.5V

OUT

678910

5

1763 G19

LT1763-1.8
GND Pin Current

1200

1000

RL = 36Ω

= 50mA*

I

800

600

400

GND PIN CURRENT (μA)

200

0

L

RL = 1.8k

= 1mA*

I

L

0123

INPUT VOLTAGE (V)

T
V
*FOR V

RL = 180Ω

= 10mA*

I

L

4

678910

5

= 25°C

J

= V

IN

SHDN

OUT

= 1.8V

1763 G20

LT1763-2.5
GND Pin Current

1200

1000

800

600

400

GND PIN CURRENT (μA)

200

0

RL = 50Ω

= 50mA*

I

L

0123

INPUT VOLTAGE (V)

RL = 250Ω

= 10mA*

I

L

RL = 2.5k

= 1mA*

I

L

4

T

= 25°C

J

= V

V

IN

SHDN

*FOR V

= 2.5V

OUT

678910

5

1763 G21

1763ff

TYPICAL PERFORMANCE CHARACTERISTICS

LT1763 Series

LT1763-3
GND Pin Current

1200

1000

800

600

400

GND PIN CURRENT (μA)

200

0

0123

RL = 60Ω

= 50mA*

I

L

INPUT VOLTAGE (V)

LT1763
GND Pin Current

1200

1000

800

600

400

GND PIN CURRENT (μA)

200

0

0123

RL = 24.4Ω

= 50mA*

I

L

RL = 122Ω

= 10mA*

I

L

RL = 1.22k

= 1mA*

I

L

INPUT VOLTAGE (V)

RL = 300Ω

= 10mA*

I

L

RL = 3k

= 1mA*

I

L

4

5

4

5

T

= 25°C

J

= V

V

IN

SHDN

*FOR V

678910

= 25°C

T

J

V

IN

*FOR V

678910

= V

SHDN

OUT

= 3V

OUT

= 1.22V

1763 G22

1763 G25

LT1763-3.3
GND Pin Current

1200

1000

800

600

400

GND PIN CURRENT (μA)

200

0

0123

RL = 66Ω

= 50mA*

I

L

INPUT VOLTAGE (V)

LT1763-1.5
GND Pin Current

12

10

RL = 3Ω

= 500mA*

I

8

6

4

GND PIN CURRENT (mA)

2

0

0123

L

INPUT VOLTAGE (V)

RL = 330Ω

= 10mA*

I

L

RL = 3.3k

= 1mA*

I

L

4

5

I

4

5

= 25°C

T

J

= V

V

IN

SHDN

*FOR V

678910

T
V
*FOR V

RL = 5Ω
I

L

RL = 15Ω

= 100mA*

L

678910

OUT

= 25°C

J

= V

IN

SHDN

OUT

= 300mA*

= 3.3V

1763 G23

= 1.5V

1763 G26

LT1763-5
GND Pin Current

1200

1000

800

600

400

GND PIN CURRENT (μA)

200

0

0123

INPUT VOLTAGE (V)

LT1763-1.8
GND Pin Current

12

10

RL = 3.6Ω

= 500mA*

8

6

4

GND PIN CURRENT (mA)

2

0

0123

I

L

INPUT VOLTAGE (V)

RL = 100Ω

= 50mA*

I

L

RL = 5k

= 1mA*

I

L

4

4

= 25°C

T

J

= V

V

IN

SHDN

*FOR V

OUT

RL = 500Ω

= 10mA*

I

L

678910

5

= 25°C

T

J

= V

V

IN

SHDN

*FOR V

RL = 6Ω
I

L

RL = 18Ω

= 100mA*

I

L

5

= 1.8V

OUT

= 300mA*

678910

= 5V

1763 G24

1763 G27

LT1763-2.5
GND Pin Current

12

10

8

6

4

GND PIN CURRENT (mA)

2

0

0123

RL = 5Ω

= 500mA*

I

L

INPUT VOLTAGE (V)

T

= 25°C

J

V

IN

*FOR V

I

4

678910

5

= V

SHDN

= 2.5V

OUT

RL = 8.33Ω

= 300mA*

I

L

RL = 25Ω

= 100mA*

L

1763 G28

LT1763-3
GND Pin Current

12

10

8

6

4

GND PIN CURRENT (mA)

2

0

0123

I

INPUT VOLTAGE (V)

RL = 6Ω

= 500mA*

L

4

T

= 25°C

J

= V

V

IN

SHDN

*FOR V

OUT

RL = 10Ω
= 300mA*

I

L

RL = 30Ω

= 100mA*

I

L

678910

5

= 3V

1763 G29

LT1763-3.3
GND Pin Current

12

10

8

6

4

GND PIN CURRENT (mA)

2

0

0123

I

INPUT VOLTAGE (V)

RL = 6.6Ω

= 500mA*

L

4

T

= 25°C

J

= V

V

IN

SHDN

*FOR V

5

= 3.3V

OUT

RL = 11Ω
= 300mA*

I

L

RL = 33Ω

= 100mA*

I

L

678910

1763 G30

1763ff

9

LT1763 Series

TYPICAL PERFORMANCE CHARACTERISTICS

LT1763-5
GND Pin Current

12

= 25°C

T

J

= V

V

IN

10

8

6

4

GND PIN CURRENT (mA)

2

0

SHDN

*FOR V

= 5V

OUT

0123

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)

4

678910

5

50

25

RL = 10Ω

= 500mA*

I

L

RL = 16.7Ω

= 300mA*

I

L

RL = 50Ω

= 100mA*

I

L

75

100

1763 G31

1763 G34

125

LT1763
GND Pin Current

12

10

RL = 2.44Ω

= 500mA*

I

8

6

4

GND PIN CURRENT (mA)

2

0

0123

L

INPUT VOLTAGE (V)

T

= 25°C

J

V

IN

*FOR V

4

678910

5

= V

SHDN

= 1.22V

OUT

RL = 4.07Ω

= 300mA*

I

L

RL = 12.2Ω

= 100mA*

I

L

1763 G32

GND Pin Current vs I

12

VIN = V

OUT(NOMINAL)

10

8

6

4

GND PIN CURRENT (mA)

2

0

0 50 100 150

OUTPUT CURRENT (mA)

200

SHDN Pin Threshold
(Off-to-On) SHDN Pin Input Current

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 = 500mA

IL = 1mA

50

25

0

TEMPERATURE (°C)

100

125

1763 G35

75

1.4

1.2

1.0

0.8

0.6

0.4

SHDN PIN INPUT CURRENT (μA)

0.2

0

0123

SHDN PIN VOLTAGE (V)

LOAD

+ 1V

300 350 400 450 500

250

4

678910

5

1763 G33

1763 G36

SHDN Pin Input Current

1.6

1.4

1.2

1.0

0.8

0.6

0.4

SHDN PIN INPUT CURRENT (μA)

0.2

0

–25 25 75 125

–50

10

V

SHDN

050

TEMPERATURE (°C)

= 20V

100

1763 G37

ADJ Pin Bias Current

140

120

100

80

60

40

ADJ PIN BIAS CURRENT (nA)

20

0

–50

–25

25

0

TEMPERATURE (°C)

Current Limit

1.0
V

= 0V

OUT

0.9

0.8

0.7

0.6

0.5

0.4

CURRENT LIMIT (A)

0.3

0.2

0.1

50

75

100

125

1763 G38

0

0

2

1

INPUT VOLTAGE (V)

4

3

5

6

7

1763 G39

1763ff

TYPICAL PERFORMANCE CHARACTERISTICS

LT1763 Series

Current Limit

1.2

1.0

0.8

0.6

0.4

CURRENT LIMIT (A)

0.2

0

–50

–25

50

25

0

TEMPERATURE (°C)

75

VIN = 7
V

OUT

100

= 0V

1763 G40

125

Reverse Output Current

100

TJ = 25°C, VIN= 0V

90

CURRENT FLOWS
INTO OUTPUT PIN

80

70

60

50

40

30

20

REVERSE OUTPUT CURRENT (μA)

10

= V

V

OUT

ADJ

LT1763-1.8

LT1763-2.5

LT1763-3

LT1763-3.3

0

0123

(LT1763)

LT1763

4

5

OUTPUT VOLTAGE (V)

LT1763-1.5

LT1763-5

678910

1763 G41

Reverse Output Current

20

VIN = 0V, V

18

= 1.5V (LT1763-1.5)

V

OUT

= 1.8V (LT1763-1.8)

V

OUT

16

= 2.5V (LT1763-2.5)

V

OUT

= 3V (LT1763-3)

V

OUT

14

= 3.3V (LT1763-3.3)

V

OUT

12

= 5V (LT1763-5)

V

OUT

10

8

6

4

REVERSE OUTPUT CURRENT (μA)

2

0

–50 0

–25

Input Ripple Rejection Input Ripple Rejection Ripple Rejection

80

70

60

C

= 10μF

50

40

30

IL = 500mA

RIPPLE REJECTION (dB)

20

= V

V

IN

OUT(NOMINAL)

1V + 50mV

10

C

BYP

0

10 1k 10k 1M

RIPPLE

RMS

= 0

100 100k

FREQUENCY (Hz)

OUT

+

C

OUT

= 4.7μF

1763 G43

80

C

= 0.01μF

BYP

70

60

50

C

= 1000pF

BYP

40

30

RIPPLE REJECTION (dB)

20

IL = 500mA

= V

V

IN

1V + 50mV

10

= 10μF

C

OUT

0

10 1k 10k 1M

C

= 100pF

BYP

OUT(NOMINAL)

100 100k

+

RIPPLE

RMS

FREQUENCY (Hz)

1763 G44

68

66

64

62

60

58

RIPPLE REJECTION (dB)

VIN = V

56

1V + 0.5V
AT f = 120Hz

54

= 500mA

I

L

52

–25 25 75 125

–50

= 1.22V (LT1763)

OUT

LT1763-1.5/-1.8/

-2.5/-3/-3.3/-5

LT1763

50

25

TEMPERATURE (°C)

OUT (NOMINAL)

P-P

+

RIPPLE

050

TEMPERATURE (°C)

100

100

125

1763 G42

1763 G45

75

LT1763
Minimum Input Voltage

2.50

2.25

2.00

1.75

1.50

1.25

1.00

0.75

0.50

MINIMUM INPUT VOLTAGE (V)

0.25

V

= 1.22V

OUT

0

–50

–25

25

0

TEMPERATURE (°C)

IL = 500mA

IL = 1mA

50

Output Noise Spectral Density
C

Load Regulation

5

LT1763

0

–5

LT1763-3

–10

–15

LOAD REGULATION (mV)

–20

VIN = V
$I

L

100

125

1763 G46

75

–25

–50

LT1763-2.5

LT1763-3.3

OUT(NOMINAL)

= 1mA TO 500mA

050–25 25 75 125

TEMPERATURE (°C)

LT1763-5

+ 1V

LT1763-1.5

LT1763-1.8

100

1763 G47

OUTPUT NOISE SPECTRAL DENSITY (μV/Hz)

0.1

0.01

= 0

BYP

10

LT1763-3

LT1763-5

1

LT1763

LT1763-1.8

C

= 10μF

OUT

= 500mA

I

L

10 1k 10k 100k

LT1763-3.3

LT1763-2.5

LT1763-1.5

100

FREQUENCY (Hz)

1763 G48

1763ff

11

LT1763 Series

TYPICAL PERFORMANCE CHARACTERISTICS

Output Noise Spectral Density

10

C

= 10μF

OUT

= 500mA

I

L

LT1763-5

1

LT1763

0.1

C

= 0.01μF

BYP

OUTPUT NOISE SPECTRAL DENSITY (μV/Hz)

0.01
10 1k 10k 100k

100

FREQUENCY (Hz)

LT1763-5
10Hz to 100kHz Output Noise
C

= 0

BYP

V

OUT

100μV/DIV

C

BYP

C

= 1000pF

= 100pF

BYP

1763 G49

RMS Output Noise
vs Bypass Capacitor

160

140

)

120

RMS

100

80

60

OUTPUT NOISE (μV

40

20

0

10

LT1763-5
10Hz to 100kHz Output Noise
C

V

OUT

100μV/DIV

LT1763-5

LT1763

LT1763-1.8

= 100pF

BYP

C

= 10μF

OUT

= 500mA

I

L

f = 10Hz TO 100kHz

LT1763-3.3

LT1763-3

LT1763-2.5

LT1763-1.5

100 1000 10000

C

(pF)

BYP

1763 G50

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

160

140

)

120

RMS

100

80

60

OUTPUT NOISE (μV

40

20

0

0.01

LT1763-5
10Hz to 100kHz Output Noise
C

V

OUT

100μV/DIV

C

= 10μF

OUT

C

BYP

C

BYP

0.1 1

= 1000pF

BYP

= 0

= 0.01μF

LT1763-5

LT1763

LT1763-5

LT1763

10 100 1000

LOAD CURRENT (mA)

1763 G51

V

OUT

100μV/DIV

C

OUT

= 500mA

I

L

= 10μF

1ms/DIV

LT1763-5
10Hz to 100kHz Output Noise
C

= 0.01μF

BYP

= 10μF

C

OUT

= 500mA

I

L

1ms/DIV

1763 G52

1763 G55

= 10μF

C

OUT

= 500mA

I

L

LT1763-5
Transient Response
C

= 0

BYP

VIN = 6V

0.4
= 10μF

C

IN

C

OUT

0.2

0

–0.2

DEVIATION (V)

OUTPUT VOLTAGE

–0.4

600

400

(mA)

200

LOAD CURRENT

0

0 200

= 10μF

1ms/DIV

400

600 800 1000

TIME (μs)

1763 G53

1763 G56

= 10μF

C

OUT

= 500mA

I

L

LT1763-5
Transient Response
C

BYP

VIN = 6V

0.10
C

IN

C

OUT

0.05

0

–0.05

DEVIATION (V)

OUTPUT VOLTAGE

–0.10

600

400

(mA)

200

LOAD CURRENT

0

0203050709010

= 0.01μF

= 10μF

= 10μF

1ms/DIV

40

TIME (μs)

1763 G54

60 80 100

1763 G57

1763ff

12

LT1763 Series

PIN FUNCTIONS

(DE12/S8)

NC (Pins 1, 4, 9, 12) DE12 Only: No Connect. No connect

pins have no connection to any internal circuitry. These
pins may be tied to either GND or V

, or left fl oating.

IN

OUT (Pins 2, 3/Pin 1): Output. The output supplies power
to the load. A minimum output capacitor of 3.3μF 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.

ADJ (Pin 5/Pin 2): Adjust. For the adjustable LT1763, this
is the input to the error amplifi er. This pin is internally
clamped to ±7V. It has a bias current of 30nA which fl ows
into the pin (see the curve of ADJ Pin Bias Current vs
Temperature in the Typical Performance Characteristics
section). The ADJ pin voltage is 1.22V referenced to ground
and the output voltage range is 1.22V to 20V.

SENSE (Pin 5/Pin 2): Output Sense. For fi xed volt­age versions of the LT1763 (LT1763-1.5/LT1763-1.8/
LT1763-2.5/LT1763-3/LT1763-3.3/LT1763-5), the SENSE
pin is the input to the error amplifi er. 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 (R

) of PC traces between the regulator and the

P

load. These may be eliminated by connecting the SENSE
pin to the output at the load as shown in Figure 1 (Kelvin
Sense Connection).

R

P

8

IN

LT1763

V

+

IN

5

SHDN

GND

Figure 1. Kelvin Sense Connection

OUT

SENSE

3

1

+

2

R

P

LOAD

1763 F01

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 10μA 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.

BYP (Pin 6/Pin 4): Bypass. The BYP pin is used to bypass
the reference of the LT1763 regulators to achieve low noise
performance from the regulator. The BYP pin is clamped
internally to ±0.6V (one V

). A small capacitor from the

BE

output to this pin will bypass the reference to lower the
output voltage noise. A maximum value of 0.01μF can
be used for reducing output voltage noise to a typical
20μV

over a 10Hz to 100kHz bandwidth. If not used,

RMS

this pin must be left unconnected.

GND (Pins 7/Pins 3, 6, 7): Ground.
SHDN (Pin 8/Pin 5): Shutdown. The SHDN pin is used

to put the LT1763 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 1μA. 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 10, 11/Pin 8): 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 fi lter 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 suffi cient.
The LT1763 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 fl ow into the regulator and no reverse
voltage will appear at the load. The device will protect both
itself and the load.

Exposed Pad (Pin 13) DE12 Only: Ground. The Exposed
Pad must be soldered to the PCB ground for rated thermal
performance.

1763ff

13

LT1763 Series

APPLICATIONS INFORMATION

The LT1763 series are 500mA low dropout regulators with
micropower quiescent current and shutdown. The devices
are capable of supplying 500mA at a dropout voltage of
300mV. Output voltage noise can be lowered to 20μV

RMS

over a 10Hz to 100kHz bandwidth with the addition of
a 0.01μF reference bypass capacitor. Additionally, the
reference bypass capacitor will improve transient response
of the regulator, lowering the settling time for transient load
conditions. The low operating quiescent current (30μA)
drops to less than 1μA in shutdown. In addition to the
low quiescent current, the LT1763 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 LT1763-X acts like it has a diode in series with
its output and prevents reverse current fl ow. 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 LT1763 has an output voltage
range of 1.22V 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 ADJ pin voltage
at 1.22V referenced to ground. The current in R1 is then
equal to 1.22V/R1 and the current in R2 is the current
in R1 plus the ADJ pin bias current. The ADJ pin bias
current, 30nA at 25°C, fl ows through R2 into the ADJ pin.
The output voltage can be calculated using the formula in
Figure 2. The value of R1 should be no greater than 250k
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. Curves
of ADJ Pin Voltage vs Temperature and ADJ Pin Bias
Current vs Temperature appear in the Typical Performance
Characteristics section.

to 1.22V: V

/1.22V. For example, load regulation for an

OUT

output current change of 1mA to 500mA is –2mV typical
at V

= 1.22V. At V

OUT

= 12V, load regulation is:

OUT

(12V/1.22V)(–2mV) = –19.6mV

IN

V

IN

OUT

LT1763

ADJ

GND

Figure 2. Adjustable Operation

R2

R1

1763 F02

V

+

OUT

R

2

⎛

VV

=+

122 1

.

OUT ADJ

VV

=

122

.

ADJ

InA

=°

30

ADJ

OUTPUT RANGE = 1.22V TO 20V

⎜
⎝

AT 25 C

⎞

IR

+

()()

⎟
⎠

R

1

2

Bypass Capacitance and Low Noise Performance

The LT1763 regulators may be used with the addition of
a bypass capacitor from V

to the BYP pin to lower

OUT

output voltage noise. A good quality low leakage capacitor
is recommended. This capacitor will bypass the reference
of the regulator, providing a low frequency noise pole.
The noise pole provided by this bypass capacitor will
lower the output voltage noise to as low as 20μV

RMS

with the addition of a 0.01μF bypass capacitor. Using
a bypass capacitor has the added benefi t of improving
transient response. With no bypass capacitor and a 10μF
output capacitor, a 10mA to 500mA load step will settle
to within 1% of its fi nal value in less than 100μs. With
the addition of a 0.01μF bypass capacitor, the output will
settle to within 1% for a 10mA to 500mA load step in less
than 10μs, with total output voltage deviation of less than

2.5% (see the LT1763-5 Transient Response curve in the
Typical Performance Characteristics section). However,
regulator start-up time is proportional to the size of the
bypass capacitor, slowing to 15ms with a 0.01μF bypass
capacitor and 10μF output capacitor.

The adjustable device is tested and specifi ed with the ADJ
pin tied to the OUT pin for an output voltage of 1.22V.
Specifi cations for output voltages greater than 1.22V will
be proportional to the ratio of the desired output voltage

14

1763ff

APPLICATIONS INFORMATION

Output Capacitance and Transient Response

The LT1763 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 3.3μF with an ESR
of 3Ω, or less, is recommended to prevent oscillations.
The LT1763-X is a micropower device and output transient
response will be a function of output capacitance. Larger
values of output capacitance decrease the peak deviations
and provide improved transient response for larger load
current changes. Bypass capacitors, used to decouple
individual components powered by the LT1763-X, will
increase the effective output capacitor value. With larger
capacitors used to bypass the reference (for low noise
operation), larger values of output capacitors are needed.
For 100pF of bypass capacitance, 4.7μF of output capaci­tor is recommended. With a 1000pF bypass capacitor or
larger, a 6.8μF output capacitor is recommended.

The shaded region of Figure 3 defi nes the range over
which the LT1763 regulators are stable. The minimum ESR
needed is defi ned by the amount of bypass capacitance
used, while the maximum ESR is 3Ω.

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 specifi ed 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 coeffi cients, as shown in Figures 4
and 5. 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

LT1763 Series

4.0

3.5

3.0

2.5

2.0

ESR (Ω)

C

BYP

1.5

1.0

0.5

0

1

20

0

–20

–40

–60

CHANGE IN VALUE (%)

–80

–100

0

Figure 4. 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

–25 0

Figure 5. Ceramic Capacitor Temperature Characteristics

STABLE REGION

= 0

C

= 100pF

BYP

OUTPUT CAPACITANCE (μF)

C

BYP

310

245

Figure 3. Stability

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

X5R

Y5V

26

4

8

DC BIAS VOLTAGE (V)

50 100 125

25 75

TEMPERATURE (°C)

= 330pF

C

BYP

10

Y5V

r 1000pF

6

12

X5R

78

14

9

1763 F03

16

1763 F04

1763 F05

1763ff

15

LT1763 Series

APPLICATIONS INFORMATION

Y5V and Z5U capacitors, but can still be signifi cant 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 verifi ed.

Voltage and temperature coeffi cients 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. The resulting voltages produced can cause
appreciable amounts of noise, especially when a ceramic
capacitor is used for noise bypassing. A ceramic capacitor
produced Figure 6’s trace in response to light tapping from a
pencil. Similar vibration induced behavior can masquerade
as increased output voltage noise.

LT1763-5

= 10μF

C

OUT

= 0.01μF

C

BYP

= 100mA

I

LOAD

V

OUT

500μV/DIV

100ms/DIV

Figure 6. Noise Resulting from
Tapping on a Ceramic Capacitor

1763 F06

Thermal Considerations

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

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

)(VIN – V

OUT

OUT

), and

2. GND pin current multiplied by the input voltage:

)(VIN).

(I

GND

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

The LT1763 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. Copper board stiffeners 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 3/32" FR-4 board with one ounce
copper.

16

Table 1. DE Package, 12-Lead DFN

COPPER AREA

BOARD AREA

2

2

2

2

2500mm

2500mm

2500mm

2500mm

2500mm

1000mm

225mm

100mm

* Device is mounted on topside

2

2

2

2

2500mm

2500mm

2500mm

2500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)TOPSIDE* BACKSIDE

2

2

2

2

40°C/W

45°C/W

50°C/W

60°C/W

1763ff

APPLICATIONS INFORMATION

LT1763 Series

Table 2. SO-8 Package, 8-Lead SO

COPPER AREA

BOARD AREA

2

2

2

2

2

2500mm

2500mm

2500mm

2500mm

2500mm

2500mm

1000mm

225mm

100mm

50mm

* Device is mounted on topside

2

2

2

2

2

2500mm

2500mm

2500mm

2500mm

2500mm

THERMAL RESISTANCE

(JUNCTION-TO-AMBIENT)TOPSIDE* BACKSIDE

2

2

2

2

2

60°C/W

60°C/W

68°C/W

74°C/W

86°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 250mA
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

= 250mA

= 6V

at (I

= 250mA, VIN = 6V) = 5mA

OUT

So,

P = 250mA(6V – 3.3V) + 5mA(6V) = 0.71W

The thermal resistance will be in the range of 60°C/W to
86°C/W, depending on the copper area. So, the junction
temperature rise above ambient will be approximately
equal to:

0.71W(75°C/W) = 53.3°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 + 53.3°C = 103.3°C

JMAX

Protection Features

The LT1763 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 fl ow into the device will be limited to less
than 1mA (typically less than 100μA) and no negative
voltage will appear at the output. The device will protect
both itself and the load. This provides protection against
batteries which can be plugged in backward.

The output of the LT1763-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 fi xed voltage versions, the output will act like a
large resistor, typically 500k or higher, limiting current fl ow
to less than 100μA. For adjustable versions, the output
will act like an open circuit; no current will fl ow 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 100k) 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

1.22V reference when the output is forced to 20V.

1763ff

17

LT1763 Series

APPLICATIONS INFORMATION

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 output
and ADJ pin 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 fl ow back into the output will follow
the curve shown in Figure 7.

100

TJ = 25°C

= 0V

V

90

IN

CURRENT FLOWS

80

INTO OUTPUT PIN

= V

V

OUT

70

60

50

LT1763-2.5
LT1763-3

40

30

20

REVERSE OUTPUT CURRENT (μA)

10

0

0123

(LT1763)

ADJ

LT1763-1.8

OUTPUT VOLTAGE (V)

LT1763

4

When the IN pin of the LT1763-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.

LT1763-1.5

LT1763-5

LT1763-3.3

678910

5

1763 F07

Figure 7. Reverse Output Current

1763ff

18

PACKAGE DESCRIPTION

LT1763 Series

DE/UE Package

12-Lead Plastic DFN (4mm × 3mm)

(Reference LTC DWG # 05-08-1695 Rev D)

0.70 p0.05

3.60 p0.05

2.20 p0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

NOTE:

1. DRAWING PROPOSED TO BE A VARIATION OF VERSION
(WGED) IN JEDEC PACKAGE OUTLINE M0-229

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

1.70 p 0.05

0.25 p 0.05

3.30 p0.05

2.50 REF

0.50 BSC

PACKAGE
OUTLINE

PIN 1

TOP MARK

(NOTE 6)

0.200 REF

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

(Reference LTC DWG # 05-08-1610)

4.00 p0.10

(2 SIDES)

R = 0.05

TYP

3.00 p0.10

(2 SIDES)

0.75 p0.05

0.00 – 0.05

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE

S8 Package

R = 0.115

TYP

3.30 p0.10

1.70 p 0.10

0.25 p 0.05

2.50 REF

BOTTOM VIEW—EXPOSED PAD

127

16

0.50 BSC

0.40 p 0.10

PIN 1 NOTCH
R = 0.20 OR

0.35 s 45o
CHAMFER

(UE12/DE12) DFN 0806 REV D

.050 BSC

.245
MIN

.030 ±.005

TYP

RECOMMENDED SOLDER PAD LAYOUT

NOTE:

1. DIMENSIONS IN

2. DRAWING NOT TO SCALE

INCHES

(MILLIMETERS)

.189 – .197

(4.801 – 5.004)

.045 ±.005

.160 ±.005

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

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.

.228 – .244

(5.791 – 6.197)

NOTE 3

7

8

1

2

5

6

.150 – .157

(3.810 – 3.988)

NOTE 3

3

4

.053 – .069

(1.346 – 1.752)

.014 – .019

(0.355 – 0.483)

TYP

(0.254 – 0.508)

.008 – .010

(0.203 – 0.254)

.010 – .020

s 45°

.016 – .050

(0.406 – 1.270)

.004 – .010

(0.101 – 0.254)

.050

(1.270)

BSC

0°– 8° TYP

SO8 0303

1763ff

19

LT1763 Series

TYPICAL APPLICATION

VIN> 3.8V

+

SHDN

Paralleling of Regulators for Higher Output Current

R1

0.1Ω

C1
10μF

R2

0.1Ω

R3

2.2k

R4

2.2k

IN

SHDN

IN

SHDN

3

+

1/2 LT1490

2

–

SENSE

LT1763-3.3

GND

LT1763

GND

8

4

OUT

BYP

OUT

BYP

ADJ

C3

0.01μF

C4

0.01μF

C5

0.01μF

R5

10k

1

1763 TA03

+

R6
2k

R7

1.21k

3.3V
1A

C2
10μF

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Includes 2.5V Reference and Comparator

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20

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear.com

1763ff

LT 0909 REV F • PRINTED IN USA

© LINEAR TECHNOLOGY CORPORATION 1999