LT1962EMS8-3.3 - Linear Technology

LT1962 Series

300mA, Low Noise,

Micropower

LDO Regulators

■

Low Noise: 20µV

RMS

(10Hz to 100kHz)

■

Output Current: 300mA

■

Low Quiescent Current: 30µA

■

Wide Input Voltage Range: 1.8V to 20V

■

Low Dropout Voltage: 270mV

■

Very Low Shutdown Current: < 1

■

No Protection Diodes Needed

■

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

■

Adjustable Output from 1.22V to 20V

■

Stable with 3.3µF Output Capacitor

■

Stable with Aluminum, Tantalum or

Ceramic Capacitors

■

Reverse Battery Protection

■

No Reverse Current

■

Overcurrent and Overtemperature Protected

■

8-Lead MSOP Package

The LT

1962 series are micropower, low noise, low

dropout regulators. The devices are capable of supplying

300mA of output current with a dropout voltage of 270mV.

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 LT1962 regulators is low output noise.

With the addition of an external 0.01µF bypass capacitor,

output noise drops to 20µV

RMS

over a 10Hz to 100kHz

bandwidth. The LT1962 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 pro-

tection, current limiting, thermal limiting and reverse cur-

rent protection. The parts come in fixed 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 LT1962 regu-

lators are available in the 8-lead MSOP package.

3.3V Low Noise Regulator

■

Cellular Phones

■

Battery-Powered Systems

■

Noise-Sensitive Instrumentation Systems

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

LOAD CURRENT (mA)

DROPOUT VOLTAGE (mV)

400

350

300

250

200

150

100

1962 TA02

100 200 30050 150 250

Dropout Voltage

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

SHDN

0.01µF

10µF

1962 TA01

OUT

SENSE

3.7V TO

20V

BYP

GND

LT1962-3.3

3.3V AT 300mA

20µV

RMS

NOISE

1µF

LT1962 Series

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Operating Voltage (LT1962) I

LOAD

= 300mA (Notes 4, 12) ●1.8 2.3 V

Regulated Output Voltage LT1962-1.5 V

= 2V, I

LOAD

= 1mA 1.485 1.500 1.515 V

(Notes 4, 5) 2.5V < V

< 20V, 1mA < I

LOAD

< 300mA ●1.462 1.500 1.538 V

LT1962-1.8 V

= 2.3V, I

LOAD

= 1mA 1.782 1.800 1.818 V

2.8V < V

< 20V, 1mA < I

LOAD

< 300mA ●1.755 1.800 1.845 V

LT1962-2.5 V

= 3V, I

LOAD

= 1mA 2.475 2.500 2.525 V

3.5V < V

< 20V, 1mA < I

LOAD

< 300mA ●2.435 2.500 2.565 V

LT1962-3 V

= 3.5V, I

LOAD

= 1mA 2.970 3.000 3.030 V

4V < V

< 20V, 1mA < I

LOAD

< 300mA ●2.925 3.000 3.075 V

LT1962-3.3 V

= 3.8V, I

LOAD

= 1mA 3.267 3.300 3.333 V

4.3V < V

< 20V, 1mA < I

LOAD

< 300mA ●3.220 3.300 3.380 V

LT1962-5 V

= 5.5V, I

LOAD

= 1mA 4.950 5.000 5.050 V

6V < V

< 20V, 1mA < I

LOAD

< 300mA ●4.875 5.000 5.125 V

ADJ Pin Voltage LT1962 V

= 2V, I

LOAD

= 1mA 1.208 1.220 1.232 V

(Notes 4, 5) 2.3V < V

< 20V, 1mA < I

LOAD

< 300mA ●1.190 1.220 1.250 V

Line Regulation LT1962-1.5 ∆V

= 2V to 20V, I

LOAD

= 1mA ●15 mV

LT1962-1.8 ∆V

= 2.3V to 20V, I

LOAD

= 1mA ●15 mV

LT1962-2.5 ∆V

= 3V to 20V, I

LOAD

= 1mA ●15 mV

LT1962-3 ∆V

= 3.5V to 20V, I

LOAD

= 1mA ●15 mV

LT1962-3.3 ∆V

= 3.8V to 20V, I

LOAD

= 1mA ●15 mV

LT1962-5 ∆V

= 5.5V to 20V, I

LOAD

= 1mA ●15 mV

LT1962 (Note 4) ∆V

= 2V to 20V, I

LOAD

= 1mA ●15 mV

Load Regulation LT1962-1.5 V

= 2.5V, ∆I

LOAD

= 1mA to 300mA 3 8 mV

= 2.5V, ∆I

LOAD

= 1mA to 300mA ●15 mV

LT1962-1.8 V

= 2.8V, ∆I

LOAD

= 1mA to 300mA 4 9 mV

= 2.8V, ∆I

LOAD

= 1mA to 300mA ●18 mV

(Note 1)

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

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

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

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

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

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

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

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

Operating Junction Temperature Range

(Note 3) ............................................ –40°C to 125°C

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

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

ABSOLUTE AXI U RATI GS

WWWU

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 3)

ELECTRICAL CHARACTERISTICS

ORDER PART

NUMBER

LT1962EMS8

LT1962EMS8-1.5

LT1962EMS8-1.8

LT1962EMS8-2.5

LT1962EMS8-3

LT1962EMS8-3.3

LT1962EMS8-5

MS8 PART MARKING

LTML

LTSZ

LTTA

LTPT

JMAX

= 150°C, θ

= 125°C/W

SEE THE APPLICATIONS

INFORMATION SECTION

FOR ADDITIONAL

INFORMATION ON

THERMAL RESISTANCE

*PIN 2: SENSE FOR LT1962-1.5/LT1962-1.8/

LT1962-2.5/LT1962-3/LT1962-3.3/LT1962-5.

ADJ FOR LT1962

OUT

SENSE/ADJ*

BYP

GND

SHDN

TOP VIEW

MS8 PACKAGE

8-LEAD PLASTIC MSOP

PACKAGE/ORDER I FOR ATIO

LTPQ

LTPS

LTPR

Consult factory for parts specified with wider operating temperature ranges.

LT1962 Series

Load Regulation LT1962-2.5 V

= 3.5V, ∆I

LOAD

= 1mA to 300mA 5 12 mV

= 3.5V, ∆I

LOAD

= 1mA to 300mA ●25 mV

LT1962-3 V

= 4V, ∆I

LOAD

= 1mA to 300mA 7 15 mV

= 4V, ∆I

LOAD

= 1mA to 300mA ●30 mV

LT1962-3.3 V

= 4.3V, ∆I

LOAD

= 1mA to 300mA 7 17 mV

= 4.3V, ∆I

LOAD

= 1mA to 300mA ●33 mV

LT1962-5 V

= 6V, ∆I

LOAD

= 1mA to 300mA 12 25 mV

= 6V, ∆I

LOAD

= 1mA to 300mA ●50 mV

LT1962 (Note 4) V

= 2.3V, ∆I

LOAD

= 1mA to 300mA 2 6 mV

= 2.3V, ∆I

LOAD

= 1mA to 300mA ●12 mV

Dropout Voltage I

LOAD

= 10mA 0.10 0.15 V

= V

OUT(NOMINAL)

LOAD

= 10mA ●0.21 V

(Notes 6, 7, 12) I

LOAD

= 50mA 0.15 0.20 V

LOAD

= 50mA ●0.28 V

LOAD

= 100mA 0.18 0.24 V

LOAD

= 100mA ●0.33 V

LOAD

= 300mA 0.27 0.33 V

LOAD

= 300mA ●0.43 V

GND Pin Current I

LOAD

= 0mA ●30 75 µA

= V

OUT(NOMINAL)

LOAD

= 1mA ●65 120 µA

(Notes 6, 8) I

LOAD

= 50mA ●1.1 1.6 mA

LOAD

= 100mA ●23 mA

LOAD

= 300mA ●812 mA

Output Voltage Noise C

OUT

= 10µF, C

BYP

= 0.01µF, I

LOAD

= 300mA, BW = 10Hz to 100kHz 20 µV

RMS

ADJ Pin Bias Current (Notes 4, 9) 30 100 nA

Shutdown Threshold V

OUT

= Off to On ●0.8 2 V

OUT

= On to Off ●0.25 0.65 V

SHDN Pin Current V

SHDN

= 0V 0.01 0.5 µA

(Note 10) V

SHDN

= 20V 1 5 µA

Quiescent Current in Shutdown V

= 6V, V

SHDN

= 0V 0.1 1 µA

Ripple Rejection V

– V

OUT

= 1.5V (Avg), V

RIPPLE

= 0.5V

P-P

, f

RIPPLE

= 120Hz, 55 65 dB

LOAD

= 300mA

Current Limit V

= 7V, V

OUT

= 0V 700 mA

= V

OUT(NOMINAL)

+ 1V, ∆V

OUT

= –0.1V ●320 mA

Input Reverse Leakage Current V

= –20V, V

OUT

= 0V ●1mA

Reverse Output Current LT1962-1.5 V

OUT

= 1.5V, V

< 1.5V 10 20 µA

(Note 11) LT1962-1.8 V

OUT

= 1.8V, V

< 1.8V 10 20 µA

LT1962-2.5 V

OUT

= 2.5V, V

< 2.5V 10 20 µA

LT1962-3 V

OUT

= 3V, V

< 3V 10 20 µA

LT1962-3.3 V

OUT

= 3.3V, V

< 3.3V 10 20 µA

LT1962-5 V

OUT

= 5V, V

< 5V 10 20 µA

LT1962 (Note 4) V

OUT

= 1.22V, V

< 1.22V 5 10 µA

PARAMETER CONDITIONS MIN TYP MAX UNITS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 3)

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: Absolute maximum input to output differential voltage cannot be

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

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

measured voltage from in to out can not exceed ±20V.

Note 3: The LT1962 regulators are tested and specified under pulse load

conditions such that T

≈ T

. The LT1962 is 100% tested at T

= 25°C.

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

and correlation with statistical process controls.

Note 4: The LT1962 (adjustable version) is tested and specified for these

conditions with the ADJ pin connected to the OUT pin.

LT1962 Series

TYPICAL PERFOR A CE CHARACTERISTICS

OUTPUT CURRENT (mA)

DROPOUT VOLTAGE (mV)

150

200

250

150 250

1962 G01

100

050 100 200

300

350

400

300

= 125°C

= 25°C

OUTPUT CURRENT (mA)

GUARANTEED DROPOUT VOLTAGE (mV)

100

200

300

50 100 150 200

1962 G02

250

400

500

150

250

350

450

300

= TEST POINTS

TJ ≤ 125°C

TJ ≤ 25°C

TEMPERATURE (°C)

–50

DROPOUT VOTLAGE (mV)

350

1962 G03

200

100

–25 0 50

400

300

250

150

75 100 125

= 300mA

= 100mA

= 50mA

= 10mA

= 1mA

Typical Dropout Voltage Guaranteed Dropout Voltage Dropout Voltage

Quiescent Current

TEMPERATURE (°C)

–50

QUIESCENT CURRENT (µA)

050 75

1962 G04

–25 25 100 125

= 6V

SHDN

= V

∞

, I

= 0 (LT1962-1.5/-1.8

/2.5/-3/-3.3/-5)

= 250k, I

= 5µA (LT1962)

Note 5: Operating conditions are limited by maximum junction

temperature. The regulated output voltage specification will not apply for

all possible combinations of input voltage and output current. When

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

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

range must be limited.

Note 6: To satisfy requirements for minimum input voltage, the LT1962

(adjustable version) is tested and specified 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 7: Dropout voltage is the minimum input to output voltage differential

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

output voltage will be equal to: V

– V

DROPOUT

Note 8: GND pin current is tested with V

= V

OUT(NOMINAL)

or V

= 2.3V

(whichever is greater) and a current source load. This means the device is

ELECTRICAL CHARACTERISTICS

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

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

included in the specification for GND pin current.

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

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

pin and out the GND pin.

Note 12: For the LT1962, LT1962-1.5 and LT1962-1.8 dropout voltage will

be limited by the minimum input voltage specification under some output

voltage/load conditions. See the curve of Minimum Input Voltage in the

Typical Performance Characteristics. For other fixed voltage versions of

the LT1962, the minimum input voltage is limited by the dropout voltage.

LT1962-1.5 Output Voltage LT1962-1.8 Output Voltage

TEMPERATURE (°C)

–50

OUTPUT VOLTAGE (V)

125

1962 G05

050 100

–25 25 75

1.532

1.524

1.516

1.508

1.500

1.492

1.484

1.476

1.468

= 1mA

TEMPERATURE (°C)

–50

OUTPUT VOLTAGE (V)

125

1962 G06

050 100

–25 25 75

1.836

1.827

1.818

1.809

1.800

1.791

1.782

1.773

1.764

= 1mA

LT1962 Series

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962-3 Quiescent Current

LT1962-3.3 Output Voltage

LT1962-5 Output Voltage LT1962 ADJ Pin Voltage

LT1962-2.5 Output Voltage LT1962-3 Output Voltage

TEMPERATURE (°C)

–50

OUTPUT VOTLAGE (V)

2.53

1962 G07

2.50

2.48

–25 0 50

2.47

2.46

2.54

2.52

2.51

2.49

75 100 125

= 1mA

TEMPERATURE (°C)

–50

OUTPUT VOTLAGE (V)

3.045

1962 G08

3.000

2.970

–25 0 50

2.955

2.940

3.060

3.030

3.015

2.985

75 100 125

= 1mA

TEMPERATURE (°C)

–50

OUTPUT VOTLAGE (V)

5.075

1962 G10

5.000

4.950

–25 0 50

4.925

4.900

5.100

5.050

5.025

4.975

75 100 125

= 1mA

TEMPERATURE (°C)

–50

ADJ PIN VOTLAGE (V)

1.235

1962 G11

1.220

1.210

–25 0 50

1.205

1.200

1.240

1.230

1.225

1.215

75 100 125

= 1mA

LT1962-1.5 Quiescent Current

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

800

700

600

500

400

300

200

100

1962 G12

246 107135 9

= 25°C

∞

SHDN

= V

SHDN

= 0V

LT1962-2.5 Quiescent CurrentLT1962-1.8 Quiescent Current

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

800

700

600

500

400

300

200

100

1962 G13

246 107135 9

= 25°C

∞

SHDN

= V

SHDN

= 0V

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

800

700

600

500

400

300

200

100

1962 G14

246 107135 9

= 25°C

∞

SHDN

= V

SHDN

= 0V

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

800

700

600

500

400

300

200

100

1962 G15

246 107135 9

= 25°C

∞

SHDN

= V

SHDN

= 0V

TEMPERATURE (°C)

–50

OUTPUT VOTLAGE (V)

3.345

1962 G09

3.300

3.270

–25 0 50

3.255

3.240

3.360

3.330

3.315

3.285

75 100 125

= 1mA

LT1962 Series

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962-3.3 Quiescent Current LT1962-5 Quiescent Current LT1962 Quiescent Current

LT1962-1.5 GND Pin Current LT1962-1.8 GND Pin Current

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

800

700

600

500

400

300

200

100

1962 G16

246 107135 9

= 25°C

∞

SHDN

= V

SHDN

= 0V

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

800

700

600

500

400

300

200

100

1962 G17

246 107135 9

= 25°C

∞

SHDN

= V

SHDN

= 0V

INPUT VOLTAGE (V)

QUIESCENT CURRENT (µA)

016

1962 G18

4 8 12 20142 6 10 18

= 25°C

= 250k

SHDN

= V

SHDN

= 0V

LT1962-3 GND Pin Current LT1962-3.3 GND Pin Current

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G19

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 1.5V

= 30Ω

= 50mA*

= 150Ω

= 10mA* R

= 1.5k

= 1mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G20

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 1.8V

= 36Ω

= 50mA*

= 180Ω

= 10mA* R

= 1.8k

= 1mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G21

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 2.5V

= 50Ω

= 50mA*

= 250Ω

= 10mA* R

= 2.5k

= 1mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G22

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 3V

= 60Ω

= 50mA*

= 300Ω

= 10mA* R

= 3k

= 1mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G23

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 3.3V

= 66Ω

= 50mA*

= 330Ω

= 10mA*

= 3.3k

= 1mA*

LT1962-2.5 GND Pin Current

LT1962-5 GND Pin Current

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G24

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 5V

= 100Ω

= 50mA*

= 500Ω

= 10mA*

= 5k

= 1mA*

LT1962 Series

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962-1.5 GND Pin Current

LT1962-3 GND Pin Current

LT1962-2.5 GND Pin Current

LT1962-1.8 GND Pin Current

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G26

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 1.5V

= 5Ω

= 300mA*

= 7.5Ω

= 200mA*

= 15Ω

= 100mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G27

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 1.8V

= 6Ω

= 300mA*

= 9Ω

= 200mA*

= 18Ω

= 100mA*

GND Pin Current vs ILOAD

LT1962 GND Pin Current

LT1962-3.3 GND Pin Current

LT1962-5 GND Pin Current

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G28

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 2.5V

= 8.33Ω

= 300mA*

= 12.5Ω

= 200mA*

= 25Ω

= 100mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G29

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 3V

= 10Ω

= 300mA*

= 15Ω

= 200mA*

= 30Ω

= 100mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G30

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 3.3V

= 11Ω

= 300mA*

= 16.5Ω

= 200mA*

= 33Ω

= 100mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G31

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 5V

= 16.7Ω

= 300mA*

= 25Ω

= 200mA*

= 50Ω

= 100mA*

INPUT VOLTAGE (V)

GND PIN CURRENT (mA)

1962 G32

246 107135 9

= 25°C

= V

SHDN

*FOR V

OUT

= 1.22V

= 4.07Ω

= 300mA*

= 6.1Ω

= 200mA*

= 12.2Ω

= 100mA*

OUTPUT CURRENT (mA)

GND PIN CURRENT (mA)

150 250

1962 G33

050 100 200

300

= V

OUT(NOMINAL)

+ 1V

LT1962 GND Pin Current

INPUT VOLTAGE (V)

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G25

10103579

= 25°C

= V

SHDN

*FOR V

OUT

= 1.22V

= 24.4Ω

= 50mA*

= 122Ω

= 10mA* R

= 1.22k

= 1mA*

LT1962 Series

SHDN Pin Threshold (On-to-Off)

TEMPERATURE (°C)

–50

SHDN PIN THRESHOLD (V)

0.1

0.3

0.4

0.5

1.0

0.7

050 75

1962 G34

0.2

0.8

0.9

0.6

–25 25 100 125

= 1mA

SHDN Pin Input Current

ADJ Pin Bias Current Current Limit

SHDN Pin Input Current

SHDN Pin Threshold (Off-to-On)

Current Limit

TYPICAL PERFOR A CE CHARACTERISTICS

TEMPERATURE (°C)

–50

SHDN PIN THRESHOLD (V)

0.1

0.3

0.4

0.5

1.0

0.7

050 75

1962 G35

0.2

0.8

0.9

0.6

–25 25 100 125

= 1mA

= 300mA

SHDN PIN VOLTAGE (V)

SHDN PIN INPUT CURRENT (µA)

0.2

0.6

0.8

1.0

1.4

157

1962 G36

0.4

1.2

4910

2368

TEMPERATURE (°C)

–50

SHDN PIN INPUT CURRENT (µA)

1.4

1962 G37

0.8

0.4

–25 0 50

0.2

1.6

1.2

1.0

0.6

75 100 125

SHDN

= 20V

TEMPERATURE (°C)

–50

25 75

1962 G38

–25 0 50 100 125

ADJ PIN BIAS CURRENT (nA)

INPUT VOLTAGE (V)

CURRENT LIMIT (A)

0.1

0.3

0.4

0.5

1.0

0.7

245

1962 G39

0.2

0.8

0.9

0.6

1367

OUT

= 0V

TEMPERATURE (°C)

–50

CURRENT LIMIT (A)

0.8

1.0

1.2

25 75

1962 G40

0.6

0.4

–25 0 50 100 125

0.2

= 7V

OUT

= 0V

OUTPUT VOLTAGE (V)

REVERSE OUTPUT CURRENT (µA)

100

897

1962 F07

02346

510

LT1962

LT1962-5

= 25°C

= 0V

CURRENT FLOWS

INTO OUTPUT PIN

OUT

= V

ADJ

(LT1962)

LT1962-1.5

LT1962-1.8

LT1962-2.5

LT1962-3

LT1962-3.3

Reverse Output Current Reverse Output Current

TEMPERATURE (°C)

–50

REVERSE OUTPUT CURRENT (µA)

25 75

1962 G42

–25 0 50 100 125

= 0V

OUT

= 1.22V (LT1962)

OUT

= 1.5V (LT1962-1.5)

OUT

= 1.8V (LT1962-1.8)

OUT

= 2.5V (LT1962-2.5)

OUT

= 3V (LT1962-3)

OUT

= 3.3V (LT1962-3.3)

OUT

= 5V (LT1962-5)

LT1962

LT1962-1.5/-1.8/-2.5/-3/-3.3/-5

LT1962 Series

TYPICAL PERFOR A CE CHARACTERISTICS

Ripple Rejection

Load Regulation Output Noise Spectral Density

Output Noise Spectral Density RMS Output Noise

vs Bypass Capacitor

LT1962 Minimum Input Voltage

Input Ripple Rejection Input Ripple Rejection

FREQUENCY (Hz)

RIPPLE REJECTION (dB)

10 1k 10k 1M

1962 G43

100 100k

= 300mA

= V

OUT(NOMINAL)

+ 1V

+ 50mV

RMS

RIPPLE

BYP

= 0

OUT

= 10µF

OUT

= 3.3µF

FREQUENCY (Hz)

RIPPLE REJECTION (dB)

10 1k 10k 1M

1962 G44

100 100k

= 300mA

= V

OUT(NOMINAL)

+ 1V

+ 50mV

RMS

RIPPLE

OUT

= 10µF

BYP

= 0.01µF

BYP

= 1000pF

BYP

= 100pF

TEMPERATURE (°C)

–50

RIPPLE REJECTION (dB)

1962 G45

–25 0 50

75 100 125

= 300mA

= V

OUT(NOMINAL)

+ 1V

+ 0.5V

P-P

RIPPLE AT f = 120Hz

TEMPERATURE (°C)

–50

MINIMUM INPUT VOLTAGE (V)

0.25

0.75

1.00

1.25

2.50

1.75

050 75

1962 G46

0.50

2.00

2.25

1.50

–25 25 100 125

OUT

= 1.22V

= 300mA

= 1mA

TEMPERATURE (°C)

–50

LOAD REGULATION (mV)

–5

25 75

1962 G47

–10

–15

–25 0 50 100 125

–20

–25

LT1962

LT1962-2.5

LT1962-1.8 LT1962-1.5

= V

OUT(NOMINAL)

+ 1V

∆I

= 1mA TO 300mA

LT1962-3

LT1962-3.3

LT1962-5

FREQUENCY (Hz)

0.1

OUTPUT NOISE SPECTRIAL DENSITY (µV/√Hz)

10 1k 10k 100k

1962 G48

0.01 100

LT1962 LT1962-2.5

LT1962-1.5

LT1962-5 LT1962-3.3

= 300mA

OUT

= 10µF

BYP

= 0 LT1962-3

LT1962-1.8

FREQUENCY (Hz)

0.1

OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)

10 1k 10k 100k

1962 G49

0.01 100

LT1962-5

LT1962

= 300mA

OUT

= 10µF

BYP

= 0.01µF

BYP

= 100pF

BYP

= 1000pF

BYP

(pF)

OUTPUT NOISE (µV

RMS

)

120

160

100 1k 10k

1962 G50

100

140

= 300mA

OUT

= 10µF

f = 10Hz to 100kHz

LT1962-5

LT1962-3.3

LT1962-3

LT1962

LT1962-2.5

LT1962-1.8

LT1962-1.5

RMS Output Noise

vs Load Current (10Hz to 100kHz)

LOAD CURRENT (mA)

OUTPUT NOISE (µV

RMS

)

100

140

160

0.01 1 10 1000

1962 G51

0.1 100

120

OUT

= 10µF

BYP

= 0µF

BYP

= 0.01µFLT1962-5

LT1962-5

LT1962

LT1962 Series

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962-5 10Hz to 100kHz

Output Noise (CBYP = 1000pF)

VOUT

100µV/DIV

COUT = 10µF 1ms/DIV 1962 G54

IL = 300mA

LT1962-5 10Hz to 100kHz

Output Noise (CBYP = 0.01µF)

VOUT

100µV/DIV

COUT = 10µF 1ms/DIV 1962 G55

IL = 300mA

LT1962-5 Transient Response

TIME (ms)

OUTPUT VOLTAGE

DEVIATION (V)LOAD CURRENT (mA)

0.2

0.4

1.6

1962 G56

–0.2

–0.4

100

200

300

0.4

0.2 0.6 0.8 1.2 1.8

1.4

1.0 2.0

= 6V

= 10µF

OUT

= 10µF

BYP

= 0

LT1962-5 Transient Response

TIME (µs)

OUTPUT VOLTAGE

DEVIATION (mV)LOAD CURRENT (mA)

0.05

0.10

400

1962 G57

–0.05

–0.10

100

200

300

100

50 150 200 300 450

350

250 500

VIN = 6V

CIN = 10µF

COUT = 10µF

CBYP = 0.01µF

LT1962-5 10Hz to 100kHz

Output Noise (CBYP = 0)

VOUT

100µV/DIV

COUT = 10µF 1ms/DIV 1962 G52

IL = 300mA

LT1962-5 10Hz to 100kHz

Output Noise (CBYP = 100pF)

VOUT

100µV/DIV

COUT = 10µF 1ms/DIV 1962 G53

IL = 300mA

PI FU CTIO S

OUT (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.

SENSE (Pin 2): Sense. For fixed voltage versions of the

LT1962 (LT1962-1.5/LT1962-1.8/LT1962-2.5/LT1962-3/

LT1962-3.3/LT1962-5), 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 (R

) of PC traces between the

regulator and the load. These may be eliminated by con-

necting 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 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.

ADJ (Pin 2): Adjust. For the adjustable LT1962, this is the

input to the error amplifier. This pin is internally clamped

to ±7V. It has a bias current of 30nA which flows into the

LT1962 Series

Figure 1. Kelvin Sense Connection

SHDN

1962 F01

OUT

SENSE

GND

LT1962

LOAD

PI FU CTIO S

pin. The ADJ pin voltage is 1.22V referenced to ground and

the output voltage range is 1.22V to 20V.

BYP (Pin 3): Bypass. The BYP pin is used to bypass the

reference of the LT1962 to achieve low noise performance

from the regulator. The BYP pin is clamped internally to

±0.6V (one V

). A small capacitor from the 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

RMS

over a

10Hz to 100kHz bandwidth. If not used, this pin must be

left unconnected.

GND (Pin 4): Ground.

SHDN (Pin 5): Shutdown. The SHDN pin is used to put the

LT1962 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 not function if

the SHDN pin is not connected.

NC (Pins 6, 7): No Connect. These pins are not internally

connected. For improved power handling capabilities,

these pins can be connected to the PC board.

IN (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

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

LT1962 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.

APPLICATIO S I FOR ATIO

WUUU

The LT1962 series are 300mA low dropout regulators with

micropower quiescent current and shutdown. The devices

are capable of supplying 300mA 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 refer-

ence 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 LT1962 regulators incorporate sev-

eral 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 LT1962-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 re-

turned 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 LT1962 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

LT1962 Series

Figure 2. Adjustable Operation

(see LT1962-5 Transient Response in the Typical Perfor-

mance Characteristics). However, regulator start-up time

is inversely proportional to the size of the bypass capaci-

tor, slowing to 15ms with a 0.01µF bypass capacitor and

10µF output capacitor.

Output Capacitance and Transient Response

The LT1962 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 capaci-

tors. A minimum output capacitor of 3.3µF with an ESR of

3Ω or less is recommended to prevent oscillations. The

LT1962-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 LT1962, will in-

crease the effective output capacitor value. With larger

capacitors used to bypass the reference (for low noise

operation), larger values of output capacitance are needed.

For 100pF of bypass capacitance, 4.7µF of output capaci-

tor is recommended. With a 1000pF bypass capacitor or

larger, a 6.8µF output capacitor is recommended.

The shaded region of Figure 3 defines the range over which

the LT1962 regulators are stable. The minimum ESR

needed is defined 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

1962 F02

OUT

ADJ

GND

LT1962

RIR

InA

OUT ADJ

ADJ









+

()()

=°

122 1 2

122

AT 25 C

OUTPUT RANGE = 1.22V TO 20V

APPLICATIO S I FOR ATIO

WUUU

plus the ADJ pin bias current. The ADJ pin bias current,

30nA 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 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.

The adjustable device is tested and specified with the ADJ

pin tied to the OUT pin for an output voltage of 1.22V.

Specifications for output voltages greater than 1.22V will

be proportional to the ratio of the desired output voltage to

1.22V: V

OUT

/1.22V. For example, load regulation for an

output current change of 1mA to 300mA is –2mV typical

at V

OUT

= 1.22V. At V

OUT

= 12V, load regulation is:

(12V/1.22V)(–2mV) = –19.7mV

Bypass Capacitance and Low Noise Performance

The LT1962 regulators may be used with the addition of a

bypass capacitor from V

OUT

to the BYP pin to lower 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 benefit of improving transient

response. With no bypass capacitor and a 10µF output

capacitor, a 10mA to 300mA load step will settle to within

1% of its final 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 300mA load step in less than

10µs, with total output voltage deviation of less than 2%

OUTPUT CAPACITANCE (µF)

ESR (Ω)

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0310

1962 F03

245

6789

STABLE REGION

BYP

= 330pF

BYP

≥ 1000pF

BYP

= 100pF

BYP

= 0

Figure 3. Stability

LT1962 Series

temperature and applied voltage. The most common

dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and

Y5V dielectrics are good for providing high capacitance in

a small package, but exhibit strong voltage and tempera-

ture coefficients as shown in Figures 4 and 5. When used

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

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

temperature range. The X5R and X7R dielectrics result in

more stable characteristics and are more suitable for use

as the output capacitor. The X7R type has better stability

across temperature, while the X5R is less expensive and

is available in higher values.

Voltage and temperature coefficients are not the only

sources of problems. Some ceramic capacitors have a

piezoelectric response. A piezoelectric device generates

voltage across its terminals due to mechanical stress,

similar to the way a piezoelectric accelerometer or micro-

Figure 5. Ceramic Capacitor Temperature Characteristics

Figure 4. Ceramic Capacitor DC Bias Characteristics

DC BIAS VOLTAGE (V)

CHANGE IN VALUE (%)

1962 F04

–20

–40

–60

–80

–100 04810

26 12 14

X5R

Y5V

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

TEMPERATURE (°C)

–50

–20

–40

–60

–80

–100 25 75

1962 F05

–25 0 50 100 125

Y5V

CHANGE IN VALUE (%)

X5R

BOTH CAPACITORS ARE 16V,

1210 CASE SIZE, 10µF

APPLICATIO S I FOR ATIO

WUUU

phone 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.

Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor

LT1962-5

COUT = 10µF

CBYP = 0.01µf

ILOAD = 100mA

VOUT

500µV/DIV

100ms/DIV 1962 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

OUT

)(V

– V

OUT

), and

2. GND pin current multiplied by the input voltage:

GND

)(V

The GND pin current can be found by examining the GND

Pin Current curves in the Typical Performance Character-

istics. Power dissipation will be equal to the sum of the two

components listed above.

The LT1962 series regulators have internal thermal limit-

ing designed to protect the device during overload condi-

tions. 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.

LT1962 Series

JMAX

= 50°C + 35.3°C = 85.3°C

Protection Features

The LT1962 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 opera-

tion, 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 (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 LT1962 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 500k or higher, limiting current

flow to less than 40µA. 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 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

For surface mount devices, heat sinking is accomplished

by using the heat spreading capabilities of the PC board

and its copper traces. Copper board stiffeners and plated

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

ated by power devices.

The following table lists thermal resistance for several

different board sizes and copper areas. All measurements

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

copper.

Table 1. Measured Thermal Resistance

COPPER AREA THERMAL RESISTANCE

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

2500mm

110°C/W

1000mm

2500mm

115°C/W

225mm

2500mm

120°C/W

100mm

2500mm

130°C/W

50mm

2500mm

140°C/W

*Device is mounted on topside.

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

100mA 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:

OUT(MAX)

IN(MAX)

– V

OUT

) + I

GND

IN(MAX)

)

where,

OUT(MAX)

= 100mA

IN(MAX)

= 6V

GND

at (I

OUT

= 100mA, V

= 6V) = 2mA

So,

P = 100mA(6V – 3.3V) + 2mA(6V) = 0.28W

The thermal resistance will be in the range of 110°C/W to

140°C/W depending on the copper area. So the junction

temperature rise above ambient will be approximately

equal to:

0.28W(125°C/W) = 35.3°C

The maximum junction temperature will then be equal to

the maximum junction temperature rise above ambient

plus the maximum ambient temperature or:

APPLICATIO S I FOR ATIO

WUUU

LT1962 Series

APPLICATIO S I FOR ATIO

WUUU

from the 1.22V 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

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 flow back into the output will follow the

curve shown in Figure 7.

When the IN pin of the LT1962 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

OUTPUT VOLTAGE (V)

REVERSE OUTPUT CURRENT (µA)

100

897

1962 F07

02346

510

LT1962

LT1962-5

= 25°C

= 0V

CURRENT FLOWS

INTO OUTPUT PIN

OUT

= V

ADJ

(LT1962)

LT1962-1.5

LT1962-1.8

LT1962-2.5

LT1962-3

LT1962-3.3

Figure 7. Reverse Output Current

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.

PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted.

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

MSOP (MS8) 1100

* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,

PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

0.021 ± 0.006

(0.53 ± 0.015)

0° – 6° TYP

SEATING

PLANE

0.007

(0.18)

0.043

(1.10)

MAX

0.009 – 0.015

(0.22 – 0.38) 0.005 ± 0.002

(0.13 ± 0.05)

0.034

(0.86)

REF

0.0256

(0.65)

BSC

0.193 ± 0.006

(4.90 ± 0.15)

8765

0.118 ± 0.004*

(3.00 ± 0.102)

0.118 ± 0.004**

(3.00 ± 0.102)

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 represen-

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

LT1962 Series

sn1962 1962fas LT/TP 0101 2K REV A • PRINTED IN USA

 LINEAR TECHNOLOGY CORP ORATION 2000

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

●

FAX: (408) 434-0507

●

www.linear-tech.com

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RMS

Noise

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

RMS

Noise

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

RMS

Noise

LT1764 3A, Fast Transient Response Low Dropout Regulator 340mV Dropout Voltage, 40µV

RMS

Noise

LT1772 Constant Frequency Current Mode Step-Down DC/DC Controller Up to 94% Efficiency, SOT-23 Package, 100% Duty Cycle

LT1963 1.5A, Fast Transient Response Low Dropout Regulator SO-8, SOT-223 Packages

Burst Mode is a trademark of Linear Technology Corporation.

0.01µF

0.1Ω

10k

2.2k

1.21k

10µF

1962 TA03

> 3.7V

3.3V

300mA

0.01µF

SHDN

OUT

BYP

GND

LT1962-3.3

SHDN

OUT

BYP

ADJ

GND

LT1962

SHDN

10µF

–

1/2 LT1490

2.2k

Paralleling of Regulators for Higher Output Current

SHDN

OUT

>2.7V

GND

LT1962-2.5

100k

10µF

*ADJUST R1 FOR 0mA TO 300mA

CONSTANT CURRENT

2.2k

LT1004-1.2

0.33µF

1µF

1962 TA04

0.1Ω

2.2k

40.2k

R1*

–

LOAD

1/2 LT1490

Adjustable Current Source

TYPICAL APPLICATIO S