ANALOG DEVICES LT 1962 EMS8 Datasheet

FEATURES

■

Low Noise: 20µV

■

Output Current: 300mA

■

Low Quiescent Current: 30µA

■

Wide Input Voltage Range: 1.8V to 20V

■

Low Dropout Voltage: 270mV

■

Very Low Shutdown Current: < 1µA

■

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

(10Hz to 100kHz)

RMS

Ceramic Capacitors

■

Reverse Battery Protection

■

No Reverse Current

■

Overcurrent and Overtemperature Protected

■

8-Lead MSOP Package

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APPLICATIO S

■

Cellular Phones

■

Battery-Powered Systems

■

Noise-Sensitive Instrumentation Systems

LT1962 Series

300mA, Low Noise,

Micropower

LDO Regulators

U

DESCRIPTIO

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
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 pro­tection, current limiting, thermal limiting and reverse cur­rent 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 regu­lators are available in the 8-lead MSOP package.

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

over a 10Hz to 100kHz

RMS

TYPICAL APPLICATIO

3.3V Low Noise Regulator

V

3.7V TO
20V

IN

1µF

IN

SHDN

OUT

SENSE

LT1962-3.3

BYP

GND

1962 TA01

U

0.01µF

+

3.3V AT 300mA
20µV

RMS

10µF

NOISE

Dropout Voltage

400

350

300

250

200

150

100

DROPOUT VOLTAGE (mV)

50

0

0

100

LOAD CURRENT (mA)

150

200

250

30050

1962 TA02

1

LT1962 Series

WWWU

ABSOLUTE AXI U RATI GS

(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

UU

W

PACKAGE/ORDER I FOR ATIO

ORDER PART

TOP VIEW

8

OUT

SENSE/ADJ*

*PIN 2: SENSE FOR LT1962-1.5/LT1962-1.8/
LT1962-2.5/LT1962-3/LT1962-3.3/LT1962-5.
ADJ FOR LT1962

Consult factory for parts specified with wider operating temperature ranges.

1
2

BYP

3

GND

4

MS8 PACKAGE

8-LEAD PLASTIC MSOP

T

= 150°C, θJA = 125°C/W

JMAX

SEE THE APPLICATIONS
INFORMATION SECTION

FOR ADDITIONAL

INFORMATION ON

THERMAL RESISTANCE

7
6
5

IN
NC
NC
SHDN

NUMBER

LT1962EMS8
LT1962EMS8-1.5
LT1962EMS8-1.8
LT1962EMS8-2.5
LT1962EMS8-3
LT1962EMS8-3.3
LT1962EMS8-5

MS8 PART MARKING

LTML
LTSZ
LTTA

LTPQ
LTPS
LTPR

LTPT

ELECTRICAL CHARACTERISTICS

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

PARAMETER CONDITIONS MIN TYP MAX UNITS

Minimum Operating Voltage (LT1962) I
Regulated Output Voltage LT1962-1.5 VIN = 2V, I

(Notes 4, 5) 2.5V < V

LT1962-1.8 VIN = 2.3V, I

LT1962-2.5 VIN = 3V, I

LT1962-3 VIN = 3.5V, I

LT1962-3.3 VIN = 3.8V, I

LT1962-5 VIN = 5.5V, I

ADJ Pin Voltage LT1962 VIN = 2V, I
(Notes 4, 5) 2.3V < V

Line Regulation LT1962-1.5 ∆VIN = 2V to 20V, I

LT1962-1.8 ∆V
LT1962-2.5 ∆V
LT1962-3 ∆V
LT1962-3.3 ∆V
LT1962-5 ∆V
LT1962 (Note 4) ∆V

Load Regulation LT1962-1.5 VIN = 2.5V, ∆I

LT1962-1.8 VIN = 2.8V, ∆I

= 300mA (Notes 4, 12) ● 1.8 2.3 V

LOAD

= 1mA 1.485 1.500 1.515 V

LOAD

IN

2.8V < V

IN

3.5V < V

IN

< 20V, 1mA < I

4V < V

IN

4.3V < V

IN

< 20V, 1mA < I

6V < V

IN

IN

= 2.3V to 20V, I

IN

= 3V to 20V, I

IN

= 3.5V to 20V, I

IN

= 3.8V to 20V, I

IN

= 5.5V to 20V, I

IN

= 2V to 20V, I

IN

= 2.5V, ∆I

V

IN

= 2.8V, ∆I

V

IN

< 20V, 1mA < I

= 1mA 1.782 1.800 1.818 V

LOAD

< 20V, 1mA < I

= 1mA 2.475 2.500 2.525 V

LOAD

< 20V, 1mA < I

= 1mA 2.970 3.000 3.030 V

LOAD

= 1mA 3.267 3.300 3.333 V

LOAD

< 20V, 1mA < I

= 1mA 4.950 5.000 5.050 V

LOAD

= 1mA 1.208 1.220 1.232 V

LOAD

< 20V, 1mA < I

LOAD

LOAD

LOAD

LOAD
LOAD
LOAD

LOAD

= 1mA to 300mA 3 8 mV

LOAD

= 1mA to 300mA ● 15 mV

LOAD

= 1mA to 300mA 4 9 mV

LOAD

= 1mA to 300mA ● 18 mV

LOAD

< 300mA ● 1.462 1.500 1.538 V

LOAD

< 300mA ● 1.755 1.800 1.845 V

LOAD

< 300mA ● 2.435 2.500 2.565 V

LOAD

< 300mA ● 2.925 3.000 3.075 V

LOAD

< 300mA ● 3.220 3.300 3.380 V

LOAD

< 300mA ● 4.875 5.000 5.125 V

LOAD

< 300mA ● 1.190 1.220 1.250 V

LOAD

= 1mA ● 15 mV

= 1mA ● 15 mV

= 1mA ● 15 mV

= 1mA ● 15 mV
= 1mA ● 15 mV
= 1mA ● 15 mV

= 1mA ● 15 mV

2

LT1962 Series

ELECTRICAL CHARACTERISTICS

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

PARAMETER CONDITIONS MIN TYP MAX UNITS

Load Regulation LT1962-2.5 VIN = 3.5V, ∆I

= 3.5V, ∆I

V

IN

LT1962-3 VIN = 4V, ∆I

= 4V, ∆I

V

IN

LT1962-3.3 VIN = 4.3V, ∆I

V

= 4.3V, ∆I

IN

LT1962-5 VIN = 6V, ∆I

V

= 6V, ∆I

IN

LT1962 (Note 4) VIN = 2.3V, ∆I

= 2.3V, ∆I

V

IN

Dropout Voltage I

= V

V

IN

OUT(NOMINAL)

(Notes 6, 7, 12)

GND Pin Current I

= V

V

IN

OUT(NOMINAL)

(Notes 6, 8)

Output Voltage Noise C

= 10mA 0.10 0.15 V

LOAD

I

= 10mA ● 0.21 V

LOAD

I

= 50mA 0.15 0.20 V

LOAD

I

= 50mA ● 0.28 V

LOAD

I

= 100mA 0.18 0.24 V

LOAD

I

= 100mA ● 0.33 V

LOAD

I

= 300mA 0.27 0.33 V

LOAD

= 300mA ● 0.43 V

I

LOAD

= 0mA ● 30 75 µA

LOAD

I

= 1mA ● 65 120 µA

LOAD

I

= 50mA ● 1.1 1.6 mA

LOAD

= 100mA ● 23 mA

I

LOAD

= 300mA ● 812 mA

I

LOAD

= 10µF, C

OUT

= 0.01µF, I

BYP

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

SHDN Pin Current V
(Note 10) V

Quiescent Current in Shutdown VIN = 6V, V
Ripple Rejection VIN – V

Current Limit VIN = 7V, V

Input Reverse Leakage Current VIN = –20V, V
Reverse Output Current LT1962-1.5 V

(Note 11) LT1962-1.8 V

= Off to On ● 0.8 2 V

OUT

= On to Off ● 0.25 0.65 V

V

OUT

= 0V 0.01 0.5 µA

SHDN

= 20V 1 5 µA

SHDN

= 0V 0.1 1 µA

SHDN

= 1.5V (Avg), V

OUT

= 300mA

I

LOAD

= 0V 700 mA

OUT

= V

V

IN

OUT(NOMINAL)

= 0V ● 1mA

OUT

LT1962-2.5 V
LT1962-3 V
LT1962-3.3 V
LT1962-5 V
LT1962 (Note 4) V

RIPPLE

+ 1V, ∆V

= 1.5V, VIN < 1.5V 10 20 µA

OUT

= 1.8V, VIN < 1.8V 10 20 µA

OUT

= 2.5V, VIN < 2.5V 10 20 µA

OUT

= 3V, VIN < 3V 10 20 µA

OUT

= 3.3V, VIN < 3.3V 10 20 µA

OUT

= 5V, VIN < 5V 10 20 µA

OUT

= 1.22V, VIN < 1.22V 5 10 µA

OUT

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.

= 1mA to 300mA 5 12 mV

LOAD

= 1mA to 300mA ● 25 mV

LOAD

= 1mA to 300mA 7 15 mV

LOAD

= 1mA to 300mA ● 30 mV

LOAD

= 1mA to 300mA 7 17 mV

LOAD

= 1mA to 300mA ● 33 mV

LOAD

= 1mA to 300mA 12 25 mV

LOAD

= 1mA to 300mA ● 50 mV

LOAD

= 1mA to 300mA 2 6 mV

LOAD

= 1mA to 300mA ● 12 mV

LOAD

= 300mA, BW = 10Hz to 100kHz 20 µV

LOAD

= 0.5V

= –0.1V ● 320 mA

OUT

P-P

, f

= 120Hz, 55 65 dB

RIPPLE

Note 3: The LT1962 regulators are tested and specified under pulse load
conditions such that T

≈ TA. The LT1962 is 100% tested at TA = 25°C.

J

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

Note 4: The LT1962 (adjustable version) is tested and specified for these
conditions with the ADJ pin connected to the OUT pin.

RMS

3

LT1962 Series

TEMPERATURE (°C)

–50

DROPOUT VOTLAGE (mV)

350

25

1962 G03

200

100

–25 0 50

50

0

400

300

250

150

75 100 125

IL = 300mA

IL = 100mA

IL = 50mA

IL = 10mA

IL = 1mA

ELECTRICAL CHARACTERISTICS

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

IN

– V

Note 8: GND pin current is tested with VIN = V

DROPOUT

.

OUT(NOMINAL)

or VIN = 2.3V

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.

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

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Typical Dropout Voltage Guaranteed Dropout Voltage Dropout Voltage

400

350

300

250

200

150

100

DROPOUT VOLTAGE (mV)

50

0

50 100 200

0

OUTPUT CURRENT (mA)

TJ = 125°C

TJ = 25°C

150

250

300

1962 G01

500

= TEST POINTS

450
400
350
300
250
200
150

100

50

GUARANTEED DROPOUT VOLTAGE (mV)

0

0

50

100

OUTPUT CURRENT (mA)

TJ ≤ 125°C

≤ 25°C

T

J

150 200

250

300

1962 G02

Quiescent Current

50
45
40
35
30
25
20
15

VIN = 6V
V

QUIESCENT CURRENT (µA)

SHDN

10

RL = ∞, IL = 0 (LT1962-1.5/-1.8
/2.5/-3/-3.3/-5)

5

R

L

0

–50

4

= V

IN

= 250k, IL = 5µA (LT1962)

50

25

0

–25

TEMPERATURE (°C)

LT1962-1.5 Output Voltage

1.532
IL = 1mA

1.524

1.516

1.508

1.500

1.492

OUTPUT VOLTAGE (V)

1.484

1.476

100

125

1962 G04

75

1.468

–50

–25

0

TEMPERATURE (°C)

50

25

75

100

125

1962 G05

LT1962-1.8 Output Voltage

1.836
IL = 1mA

1.827

1.818

1.809

1.800

1.791

OUTPUT VOLTAGE (V)

1.782

1.773

1.764

–50

–25

0

25

TEMPERATURE (°C)

50

75

100

125

1962 G06

UW

TEMPERATURE (°C)

–50

OUTPUT VOTLAGE (V)

3.345

25

1962 G09

3.300

3.270

–25 0 50

3.255

3.240

3.360

3.330

3.315

3.285

75 100 125

IL = 1mA

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962 Series

LT1962-2.5 Output Voltage

2.54
IL = 1mA

2.53

2.52

2.51

2.50

2.49

OUTPUT VOTLAGE (V)

2.48

2.47

2.46

–25 0 50

–50

25

TEMPERATURE (°C)

75 100 125

1962 G07

LT1962-3 Output Voltage

3.060
IL = 1mA

3.045

3.030

3.015

3.000

2.985

OUTPUT VOTLAGE (V)

2.970

2.955

2.940

–25 0 50

–50

TEMPERATURE (°C)

LT1962-5 Output Voltage LT1962 ADJ Pin Voltage

5.100
IL = 1mA

5.075

5.050

5.025

5.000

4.975

OUTPUT VOTLAGE (V)

4.950

4.925

4.900

–25 0 50

–50

25

TEMPERATURE (°C)

75 100 125

1962 G10

1.240
IL = 1mA

1.235

1.230

1.225

1.220

1.215

ADJ PIN VOTLAGE (V)

1.210

1.205

1.200

–25 0 50

–50

TEMPERATURE (°C)

LT1962-3.3 Output Voltage

25

75 100 125

1962 G08

LT1962-1.5 Quiescent Current

800

700

600

500

400

300

200

QUIESCENT CURRENT (µA)

100

25

75 100 125

1962 G11

0

0

V

= V

SHDN

246 107135 9

INPUT VOLTAGE (V)

TJ = 25°C

=

∞

R

L

V

= 0V

SHDN

IN

8

1962 G12

800

700

600

500

400

300

200

QUIESCENT CURRENT (µA)

100

0

V

= V

SHDN

IN

246 107135 9

0

INPUT VOLTAGE (V)

V

SHDN

TJ = 25°C

=

∞

R

L

= 0V

8

1962 G13

LT1962-2.5 Quiescent CurrentLT1962-1.8 Quiescent Current

800

700

600

500

400

300

200

QUIESCENT CURRENT (µA)

100

0

0

V

= V

SHDN

246 107135 9

INPUT VOLTAGE (V)

TJ = 25°C

=

∞

R

L

V

= 0V

SHDN

IN

8

1962 G14

LT1962-3 Quiescent Current

800

700

600

500

400

300

200

QUIESCENT CURRENT (µA)

100

0

0

V

= V

SHDN

246 107135 9

INPUT VOLTAGE (V)

TJ = 25°C

=

∞

R

L

V

= 0V

SHDN

IN

8

1962 G15

5

LT1962 Series

INPUT VOLTAGE (V)

0

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G21

10103579

TJ = 25°C
V

IN

= V

SHDN

*FOR V

OUT

= 2.5V

RL = 50Ω
I

L

= 50mA*

RL = 250Ω
I

L

= 10mA*

RL = 2.5k
I

L

= 1mA*

INPUT VOLTAGE (V)

0

GND PIN CURRENT (µA)

500

1000

1500

250

750

1250

2468

1962 G24

10103579

TJ = 25°C
V

IN

= V

SHDN

*FOR V

OUT

= 5V

RL = 100Ω
I

L

= 50mA*

RL = 500Ω
I

L

= 10mA*

RL = 5k
I

L

= 1mA*

UW

TYPICAL PERFOR A CE CHARACTERISTICS

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

800

700

TJ = 25°C

=

∞

R

L

600

500

400

300

200

QUIESCENT CURRENT (µA)

100

0

0

V

246 107135 9

SHDN

= V

V

= 0V

SHDN

IN

8

INPUT VOLTAGE (V)

1962 G16

800

700

TJ = 25°C

=

∞

R

L

600

500

400

300

200

QUIESCENT CURRENT (µA)

100

0

246 107135 9

0

V

SHDN

V

= V

SHDN

IN

= 0V

8

INPUT VOLTAGE (V)

1962 G17

40

TJ = 25°C

= 250k

R

L

35

30

V

SHDN

25

20

15

10

QUIESCENT CURRENT (µA)

5

V

0

0

SHDN

4 8 12 20142 6 10 18

INPUT VOLTAGE (V)

= V

= 0V

IN

16

1962 G18

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

1500

1250

1000

GND PIN CURRENT (µA)

750

500

250

TJ = 25°C

= V

V

IN

SHDN

*FOR V

RL = 30Ω

= 50mA*

I

L

RL = 150Ω

= 10mA*

I

L

0

2468

INPUT VOLTAGE (V)

OUT

RL = 1.5k

= 1mA*

I

L

= 1.5V

10103579

1962 G19

1500

1250

1000

GND PIN CURRENT (µA)

750

500

250

RL = 36Ω

= 50mA*

I

L

RL = 180Ω

= 10mA*

I

L

0

2468

INPUT VOLTAGE (V)

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

1500

1250

1000

750

500

GND PIN CURRENT (µA)

250

0

TJ = 25°C

= V

V

IN

SHDN

*FOR V

OUT

RL = 60Ω

= 50mA*

I

L

RL = 300Ω

= 10mA*

I

L

2468

INPUT VOLTAGE (V)

RL = 3k

= 1mA*

I

L

= 3V

10103579

1962 G22

1500

1250

1000

GND PIN CURRENT (µA)

750

500

250

RL = 66Ω

= 50mA*

I

L

RL = 330Ω

= 10mA*

I

L

0

2468

INPUT VOLTAGE (V)

TJ = 25°C

= V

V

IN

*FOR V

RL = 1.8k

= 1mA*

I

L

TJ = 25°C

= V

V

IN

*FOR V

RL = 3.3k

= 1mA*

I

L

SHDN
OUT

SHDN

OUT

LT1962-2.5 GND Pin Current

= 1.8V

10103579

1962 G20

LT1962-5 GND Pin Current

= 3.3V

10103579

1962 G23

6

UW

OUTPUT CURRENT (mA)

0

GND PIN CURRENT (mA)

3

4

5

150

250

1962 G33

2

1

0

50 100 200

6

7

8

300

VIN = V

OUT(NOMINAL)

+ 1V

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962 Series

LT1962 GND Pin Current

1500

1250

RL = 24.4Ω
I

= 50mA*

1000

750

500

GND PIN CURRENT (µA)

250

0

L

RL = 122Ω

= 10mA*

I

L

2468

INPUT VOLTAGE (V)

LT1962-2.5 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

0

0

RL = 8.33Ω

= 300mA*

I

L

RL = 25Ω

= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

TJ = 25°C

= V

V

IN

*FOR V

TJ = 25°C

= V

V

IN

*FOR V

RL = 12.5Ω

I

= 200mA*

L

SHDN

= 1.22V

OUT

RL = 1.22k

= 1mA*

I

L

SHDN

= 2.5V

OUT

8

1962 G25

1962 G28

10103579

LT1962-1.5 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

0

0

RL = 5Ω

I

= 300mA*

L

RL = 15Ω
= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

LT1962-3 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

0

0

RL = 10Ω
= 300mA*

I

L

I

RL = 30Ω
= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

TJ = 25°C
V

= V

IN

*FOR V

RL = 7.5Ω

= 200mA*

I

L

TJ = 25°C
V

IN

*FOR V

RL = 15Ω

= 200mA*

L

= V

SHDN

OUT

8

SHDN

8

= 1.5V

OUT

1962 G26

= 3V

1962 G29

LT1962-1.8 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

0

0

RL = 6Ω

I

= 300mA*

L

RL = 9Ω

= 200mA*

I

L

RL = 18Ω

= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

LT1962-3.3 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

0

0

RL = 11Ω
= 300mA*

I

L

RL = 33Ω
= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

TJ = 25°C
V

= V

IN

*FOR V

TJ = 25°C

= V

V

IN

*FOR V

RL = 16.5Ω

= 200mA*

I

L

SHDN

OUT

8

SHDN

OUT

8

= 1.8V

1962 G27

= 3.3V

1962 G30

LT1962-5 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

0

0

TJ = 25°C

= V

V

IN

SHDN

*FOR V

= 5V

OUT

RL = 16.7Ω

= 300mA*

I

L

RL = 25Ω
= 200mA*

I

L

RL = 50Ω
= 100mA*

I

L

246 107135 9

INPUT VOLTAGE (V)

LT1962 GND Pin Current

8

7

6

5

4

3

GND PIN CURRENT (mA)

2

1

8

1962 G31

0

0

RL = 4.07Ω
I

L

I

L

RL = 12.2Ω

I

L

246 107135 9

INPUT VOLTAGE (V)

= 300mA*

RL = 6.1Ω

= 200mA*

= 100mA*

TJ = 25°C

= V

V

IN

*FOR V

SHDN

OUT

= 1.22V

8

1962 G32

GND Pin Current vs I

LOAD

7

LT1962 Series

SHDN PIN VOLTAGE (V)

0

0

SHDN PIN INPUT CURRENT (µA)

0.2

0.6

0.8

1.0

1.4

1

5

7

1962 G36

0.4

1.2

4

9

10

2

3

68

INPUT VOLTAGE (V)

0

0

CURRENT LIMIT (A)

0.1

0.3

0.4

0.5

1.0

0.7

2

4

5

1962 G39

0.2

0.8

0.9

0.6

1

3

6

7

V

OUT

= 0V

TEMPERATURE (°C)

–50

REVERSE OUTPUT CURRENT (µA)

20

25

30

25 75

1962 G42

15

10

–25 0

50 100 125

5

0

VIN = 0V
V

OUT

= 1.22V (LT1962)

V

OUT

= 1.5V (LT1962-1.5)

V

OUT

= 1.8V (LT1962-1.8)

V

OUT

= 2.5V (LT1962-2.5)

V

OUT

= 3V (LT1962-3)

V

OUT

= 3.3V (LT1962-3.3)

V

OUT

= 5V (LT1962-5)

LT1962

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

UW

TYPICAL PERFOR A CE CHARACTERISTICS

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)

50

25

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 0 50

–50

25

TEMPERATURE (°C)

100

= 20V

125

1962 G34

1962 G37

75

V

SHDN

75 100 125

SHDN Pin Threshold (Off-to-On)

1.0

0.9

0.8

0.7

0.6
IL = 1mA

0.5

0.4

0.3

SHDN PIN THRESHOLD (V)

0.2

0.1

0

–50

–25

0

IL = 300mA

50

25

TEMPERATURE (°C)

100

125

1962 G35

75

SHDN Pin Input Current

ADJ Pin Bias Current Current Limit

35

30

25

20

15

10

ADJ PIN BIAS CURRENT (nA)

5

0

–50

–25 0

TEMPERATURE (°C)

50 100 125

25 75

1962 G38

1.2

1.0

0.8

0.6

0.4

CURRENT LIMIT (A)

0.2

8

Current Limit

VIN = 7V

= 0V

V

OUT

0

–50

–25 0

TEMPERATURE (°C)

50 100 125

25 75

Reverse Output Current Reverse Output Current

100

TJ = 25°C

90

= 0V

V

IN

CURRENT FLOWS

80

INTO OUTPUT PIN

= V

ADJ

LT1962-1.8

LT1962-2.5

LT1962-3

LT1962-3.3

23

OUTPUT VOLTAGE (V)

(LT1962)

LT1962-1.5

465

V

OUT

70
60
50
40
30
20

REVERSE OUTPUT CURRENT (µA)

10

0

01

1962 G40

LT1962

LT1962-5

897

10

1962 F07

UW

TEMPERATURE (°C)

–50

RIPPLE REJECTION (dB)

66

25

1962 G45

60

56

–25 0 50

54

52

68

64

62

58

75 100 125

IL = 300mA
V

IN

= V

OUT(NOMINAL)

+ 1V

+ 0.5V

P-P

RIPPLE AT f = 120Hz

LOAD CURRENT (mA)

40

OUTPUT NOISE (µV

RMS

)

60

100

140

160

0.01 1 10 1000

1962 G51

20

0.1

100

120

80

0

C

OUT

= 10µF

C

BYP

= 0µF

C

BYP

= 0.01µF

LT1962-5

LT1962-5

LT1962

LT1962

TYPICAL PERFOR A CE CHARACTERISTICS

LT1962 Series

Input Ripple Rejection

80

70

60

50

40

30

RIPPLE REJECTION (dB)

20

10

0

100

10 1k 10k 1M

IL = 300mA

= V

V

IN

OUT(NOMINAL)

+ 50mV

RMS

= 0

C

BYP

C

OUT

C

= 3.3µF

OUT

FREQUENCY (Hz)

RIPPLE

= 10µF

LT1962 Minimum Input Voltage

2.50
V

= 1.22V

OUT

2.25

2.00

1.75

1.50

1.25

1.00

0.75

0.50

MINIMUM INPUT VOLTAGE (V)

0.25

0

–50

–25

0

IL = 300mA

IL = 1mA

50

25

TEMPERATURE (°C)

75

100k

100

+ 1V

1962 G43

1962 G46

125

Input Ripple Rejection

80

C

= 0.01µF

BYP

70

60

50

C

= 100pF

BYP

40

30

RIPPLE REJECTION (dB)

20

IL = 300mA

= V

V

IN

10

0

OUT(NOMINAL)

+ 50mV

RMS

= 10µF

C

OUT

100

10 1k 10k 1M

C

BYP

+ 1V

RIPPLE

FREQUENCY (Hz)

= 1000pF

Load Regulation

5

LT1962

0

–5

LT1962-3.3

–10

–15

LOAD REGULATION (mV)

–20

VIN = V
∆I

= 1mA TO 300mA

L

–25

–50

–25 0

LT1962-1.8

LT1962-3

LT1962-2.5

OUT(NOMINAL)

25 75

TEMPERATURE (°C)

LT1962-1.5

LT1962-5

+ 1V

50 100 125

100k

1962 G44

1962 G47

Ripple Rejection

Output Noise Spectral Density

10

IL = 300mA

= 10µF

C

OUT

= 0

C

BYP

LT1962-5

1

LT1962

0.1

OUTPUT NOISE SPECTRIAL DENSITY (µV/√Hz)

0.01
10 1k 10k 100k

LT1962-3.3

LT1962-2.5

LT1962-1.8

100

FREQUENCY (Hz)

LT1962-3

LT1962-1.5

1962 G48

Output Noise Spectral Density

10

IL = 300mA

= 10µF

C

OUT

LT1962-5

1

LT1962

C

= 0.01µF

BYP

0.1

OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz)

0.01
10 1k 10k 100k

100

FREQUENCY (Hz)

C

BYP

= 1000pF

C

BYP

= 100pF

1962 G49

RMS Output Noise
vs Bypass Capacitor

160

IL = 300mA

= 10µF

C

OUT

140

f = 10Hz to 100kHz

)

120

LT1962-5

RMS

100

80

60

OUTPUT NOISE (µV

40

LT1962

20

0

10

LT1962-3

LT1962-3.3

LT1962-2.5

LT1962-1.8

LT1962-1.5

100 1k 10k

C

(pF)

BYP

1962 G50

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

9

LT1962 Series

UW

TYPICAL PERFOR A CE CHARACTERISTICS

V

OUT

100µV/DIV

V

OUT

100µV/DIV

LT1962-5 10Hz to 100kHz
Output Noise (C

= 10µF 1ms/DIV 1962 G52

C

OUT

IL = 300mA

BYP

= 0)

LT1962-5 10Hz to 100kHz
Output Noise (C

C

= 10µF 1ms/DIV 1962 G55

OUT

IL = 300mA

= 0.01µF)

BYP

LT1962-5 10Hz to 100kHz
Output Noise (C

V

OUT

100µV/DIV

= 10µF 1ms/DIV 1962 G53

C

OUT

IL = 300mA

LT1962-5 Transient Response

VIN = 6V

0.4

= 10µF

C

IN

= 10µF

C

OUT

0.2

= 0

C

BYP

0

–0.2

DEVIATION (V)LOAD CURRENT (mA)

OUTPUT VOLTAGE

–0.4

300
200
100

0

0.4

0.6

0.2

0

0.8
TIME (ms)

BYP

1.0

= 100pF)

1.2

1.4

1.6

1.8

1962 G56

100µV/DIV

OUTPUT VOLTAGE

2.0

LT1962-5 10Hz to 100kHz
Output Noise (C

V

OUT

= 10µF 1ms/DIV 1962 G54

C

OUT

IL = 300mA

BYP

LT1962-5 Transient Response

0.10

0.05
0

–0.05

DEVIATION (mV)LOAD CURRENT (mA)

–0.10

300
200
100

0

10050150

0

200

250

TIME (µs)

= 1000pF)

VIN = 6V

= 10µF

C

IN

= 10µF

C

OUT

= 0.01µF

C

BYP

300

350

400

450

1962 G57

500

U

UU

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

10

are caused by the resistance (RP) of PC traces between the
regulator and the load. These may be eliminated by con­necting the SENSE pin to the output at the load as shown
in Figure 1 (Kelvin Sense Connection). Note that the
voltage drop across the external PC traces will add to the
dropout voltage of the regulator. The SENSE pin bias
current is 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

U

UU

PI FU CTIO S

R

P

SENSE

4

OUT

1

2

+

R

P

1962 F01

LOAD

RMS

over a

8

IN

LT1962

V

+

IN

5

SHDN

GND

Figure 1. Kelvin Sense Connection

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 VBE). 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
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 open­collector logic with a pull-up resistor. The pull-up resistor
is required to supply the pull-up current of the open­collector gate, normally several microamperes, and the
SHDN pin current, typically 1µA. If unused, the SHDN pin
must be connected to VIN. 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.

WUUU

APPLICATIO S I FOR ATIO

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
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 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

RMS

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 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 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

11

LT1962 Series

WUUU

APPLICATIO S I FOR ATIO

IN

V

IN

VV

VV
InA

ADJ

OUTPUT RANGE = 1.22V TO 20V

OUT

LT1962

ADJ

GND

122 1

.

=+

OUT ADJ

=

122

.

ADJ

=°

30

AT 25 C

R2

R1

2

R





IR

+




()()




1

R

V

OUT

+

1962 F02

2

Figure 2. Adjustable Operation

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

/1.22V. For example, load regulation for an

OUT

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

= 1.22V. At V

OUT

= 12V, load regulation is:

OUT

(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

to the BYP pin to lower output

OUT

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

with the

RMS

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%

(see LT1962-5 Transient Response in the Typical Perfor­mance Characteristics). However, regulator start-up time
is inversely proportional to the size of the bypass capaci­tor, 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 capaci­tors. 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 in­crease 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

4.0

3.5

3.0

2.5

2.0

ESR (Ω)

C

BYP

1.5

1.0

0.5

0

1

STABLE REGION

= 0

C

= 100pF

BYP

OUTPUT CAPACITANCE (µF)

C

= 330pF

BYP

C

310

245678

Figure 3. Stability

≥ 1000pF

BYP

9

1962 F03

12

WUUU

APPLICATIO S I FOR ATIO

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 tempera­ture 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-

20

0

–20

–40

–60

CHANGE IN VALUE (%)

–80

–100

0

Figure 4. Ceramic Capacitor DC Bias Characteristics

40

20

0

–20

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

X5R

Y5V

26

4

8

DC BIAS VOLTAGE (V)

14

12

10

16

1962 F04

X5R

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.

LT1962-5

= 10µF

C

OUT

= 0.01µf

C

BYP

I

= 100mA

LOAD

V

OUT

500µV/DIV

100ms/DIV

1962 F06

Figure 6. Noise Resulting from Tapping on a Ceramic Capacitor

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:
(I

)(VIN).

GND

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

–40

–60

CHANGE IN VALUE (%)

–80

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

–100

–50

–25 0

TEMPERATURE (°C)

Y5V

50 100 125

25 75

1962 F05

Figure 5. Ceramic Capacitor Temperature Characteristics

The LT1962 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.

13

LT1962 Series

WUUU

APPLICATIO S I FOR ATIO

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 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)

2500mm22500mm
1000mm22500mm

225mm22500mm
100mm22500mm

50mm22500mm

*Device is mounted on topside.

2

2500mm

2

2500mm

2

2500mm

2

2500mm

2

2500mm

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:

I

OUT(MAX)(VIN(MAX)

– V

where,

I

OUT(MAX)

V

IN(MAX)

I

GND

at (I

= 100mA

= 6V

= 100mA, VIN = 6V) = 2mA

OUT

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:

OUT

2

2

2

2

2

) + I

GND(VIN(MAX)

110°C/W
115°C/W
120°C/W
130°C/W
140°C/W

)

T

= 50°C + 35.3°C = 85.3°C

JMAX

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 opera­tion, the junction temperature should not exceed 125°C.

The input of the device will withstand reverse voltages of
20V. Current flow into the device will be limited to less than
1mA (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

14

WUUU

APPLICATIO S I FOR ATIO

LT1962 Series

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

U

PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted.

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.

100

TJ = 25°C

90

= 0V

V

IN

CURRENT FLOWS

80

INTO OUTPUT PIN

= V

ADJ

LT1962-1.8

LT1962-2.5

LT1962-3

LT1962-3.3

23

(LT1962)

LT1962-1.5

465

OUTPUT VOLTAGE (V)

V

OUT

70
60
50
40
30
20

REVERSE OUTPUT CURRENT (µA)

10

0

01

Figure 7. Reverse Output Current

LT1962

LT1962-5

897

10

1962 F07

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

0.118 ± 0.004*
(3.00 ± 0.102)

0.193 ± 0.006

(4.90 ± 0.15)

0.007

(0.18)

0.021

± 0.006

(0.53 ± 0.015)

* 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

° – 6° TYP

0

SEATING

PLANE

0.009 – 0.015
(0.22 – 0.38)

0.043

(1.10)

MAX

8

12

0.0256
(0.65)

BSC

7

6

5

4

3

0.118 ± 0.004**
(3.00 ± 0.102)

0.034

(0.86)

REF

0.005

± 0.002

(0.13 ± 0.05)

MSOP (MS8) 1100

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen­tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LT1962 Series

TYPICAL APPLICATIO S

U

Adjustable Current Source

+

V

IN

>2.7V

*ADJUST R1 FOR 0mA TO 300mA
CONSTANT CURRENT

LT1004-1.2

C1
10µF

R3

2k

R1*

40.2k

Paralleling of Regulators for Higher Output Current

C1
10µF

0.1Ω

R2

0.1Ω

2.2k

R1

IN

SHDN

IN

SHDN

R3

R4

2.2k
3

2

LT1962-3.3

GND

LT1962

GND

+

1/2 LT1490

–

C3

0.01µF

OUT

FB

C4

0.01µF

BYP

OUT

BYP

ADJ

8

4

C5

0.01µF

R5

10k

1

1962 TA03

+

R6
2k

R7

1.21k

C2
10µF

3.3V
300mA

R5

0.1Ω

1k

R2

R4

2.2k

C2
1µF

R6

2.2k

IN

LT1962-2.5

SHDN

–

1/2 LT1490

+

GND

OUT

C3

0.33µF

FB

1962 TA04

LOAD

R7
100k

V

> 3.7V

IN

+

SHDN

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Burst Mode is a trademark of Linear Technology Corporation.

Linear T echnolog y Corporation

16

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear-tech.com

Includes 2.5V Reference and Comparator

500mV Dropout Voltage

Noise

RMS

Noise

RMS

Noise

RMS

Noise

RMS

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

 LINEAR TECHNOLOGY CORPORATION 2000