ANALOG DEVICES LT 1521 CST-3.3 Datasheet

OUTPUT CURRENT (mA)

0

0

DROPOUT VOLTAGE (V)

0.1

0.2

0.3

0.4

0.6

50

100 150 200

LT1521 • TA02

250 300

0.5

FEATURES

LT1521/LT1521-3

LT1521-3.3/LT1521-5

300mA Low Dropout

Regulators with Micropower

Quiescent Current and Shutdown

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DESCRIPTIO

■

Dropout Voltage: 0.5V

■

Output Current: 300mA

■

Quiescent Current: 12µA

■

No Protection Diodes Needed

■

Adjustable Output from 3.8V to 20V

■

Fixed Output Voltages: 3V, 3.3V, 5V

■

Controlled Quiescent Current in Dropout

■

Shutdown IQ = 6µA

■

Reverse Battery Protection

■

No Reverse Current

■

Thermal Limiting

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APPLICATIO S

■

Low Current Regulator

■

Regulator for Battery-Powered Systems

■

Post Regulator for Switching Supplies

The LT®1521/LT1521-3/LT1521-3.3/LT1521-5 are low
dropout regulators with micropower quiescent current
and shutdown. These devices are capable of supplying
300mA of output current with a dropout voltage of 0.5V.
Designed for use in battery-powered systems, the low
quiescent current, 12µA operating and 6µA in
shutdown, makes them an ideal choice. The quiescent
current is well controlled; it does not rise in dropout as it
does with many other low dropout PNP regulators.

Other features of the LT1521/LT1521-3/LT1521-3.3/
LT1521-5 include the ability to operate with very small
output capacitors. They are stable with only 1.5µF on the
output while most older devices require between 10µF and
100µF for stability. Small ceramic capacitors can be used,
enhancing manufacturability. Also, the input may be con­nected to voltages lower than the output voltage, including
negative voltages, without reverse current flow from out­put to input. This makes the LT1521 series ideal for backup
power situations where the output is held high and the
input is low or reversed. Under these conditions only 5µA
will flow from the output pin to ground.

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

TYPICAL APPLICATIO

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5V Battery-Powered Supply with Shutdown

6V 1.5µF1µF

8

IN

5

SHDN

V

SHDN

<0.25 OFF
>2.80 ON

LT1521-5

GND

3

(PIN 5) OUTPUT

NC ON

OUT

SENSE

1

2

Dropout Voltage

5V
300mA

+

LT1521 • TA01

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LT1521/LT1521-3
LT1521-3.3/LT1521-5

WW

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

Input Voltage ...................................................... ±20V*

Output Pin Reverse Current .................................. 10mA

Adjust Pin Current ................................................ 10mA

Shutdown Pin Input Voltage (Note 1) ..........6.5V, –0.6V

Shutdown Pin Input Current (Note 1) ..................... 5mA

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

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W

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PACKAGE/ORDER INFORMATION

TOP VIEW

OUT

SENSE/ADJ*

1
2

NC

3

GND

4

MS8 PACKAGE

8-LEAD PLASTIC MSOP

*PIN 2 = SENSE FOR LT1521-3/
LT1521-3.3/LT1521-5

PIN 2 = ADJ FOR LT1521

T

= 125°C, θJA = 125°C/W

JMAX

8
7
6
5

IN
NC
NC
SHDN

SENSE/ADJ*

*PIN 2 = SENSE FOR LT1521-3/LT1521-3.3/LT1521-5

SEE THE APPLICATIONS INFORMATION SECTION

1

OUT

2

GND

3

NC

4

8-LEAD PLASTIC SO

= ADJ FOR LT1521

T

= 125°C, θJA = 70°C/W

JMAX

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

Operating Junction Temperature Range (Note 2)

Commercial ...........................................0°C to 125°C

Industrial ......................................... – 40°C to 125°C

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

*For applications requiring input voltage ratings greater than 20V, contact
the factory.

TOP VIEW

S8 PACKAGE

8

IN
GND

7

GND

6

SHDN

5

TAB IS

SEE THE APPLICATIONS INFORMATION SECTION

FRONT VIEW

GND

ST PACKAGE

3-LEAD PLASTIC SOT-223

T

= 125°C, θJA = 50°C/W

JMAX

3

OUT

2

GND

1

IN

ORDER PART NUMBER

LT1521CMS8
LT1521CMS8-3
LT1521CMS8-3.3
LT1521CMS8-5

ORDER PART NUMBER

LT1521CS8
LT1521CS8-3
LT1521CS8-3.3
LT1521CS8-5
LT1521IS8
LT1521IS8-3
LT1521IS8-3.3
LT1521IS8-5

MS8 PART MARKING

LTEZ
LTFB
LTDU
LTFA

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

S8 PART MARKING

1521
15213
152133
15215

1521I
1521I3
1521I33
1521I5

ORDER PART NUMBER

LT1521CST-3
LT1521CST-3.3
LT1521CST-5
LT1521IST-3
LT1521IST-3.3
LT1521IST-5

ST PART MARKING

15213
152133
15215

1521I3
1521I33
1521I5

2

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LT1521/LT1521-3

LT1521-3.3/LT1521-5

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Regulated Output Voltage LT1521-3 VIN = 3.5V, I
(Note 4) 4V < VIN < 20V, 1mA < I

LT1521-3.3 VIN = 3.8V, I

4.3V < VIN < 20V, 1mA < I

LT1521-5 VIN = 5.5V, I

6V < VIN < 20V, 1mA < I

LT1521 (Note 5) VIN = 4.3V, I

4.8V < VIN < 20V, 1mA < I

Line Regulation LT1521-3 ∆VIN = 4.5 to 20V, I

LT1521-3.3 ∆VIN = 4.8 to 20V, I
LT1521-5 ∆VIN = 5.5 to 20V, I
LT1521 (Note 5) ∆VIN = 4.3 to 20V, I

Load Regulation LT1521-3 ∆I

LT1521-3.3 ∆I
LT1521-5 ∆I
LT1521 (Note 5) ∆I
LT1521-3 ∆I
LT1521-3.3 ∆I
LT1521-5 ∆I
LT1521 (Note 5) ∆I

Dropout Voltage (Note 6) I

Ground Pin Current (Note 7) I

= 1mA, TJ = 25°C 130 170 mV

LOAD

I

= 1mA ● 250 mV

LOAD

I

= 50mA, TJ = 25°C 290 350 mV

LOAD

I

= 50mA ● 450 mV

LOAD

I

= 100mA, TJ = 25°C 350 420 mV

LOAD

I

= 100mA ● 550 mV

LOAD

I

= 150mA, TJ = 25°C 400 470 mV

LOAD

I

= 150mA ● 600 mV

LOAD

I

= 300mA, TJ = 25°C 500 600 mV

LOAD

I

= 300mA ● 750 mV

LOAD

= 0mA ● 12 25 µA

LOAD

I

= 1mA ● 65 100 µA

LOAD

I

= 10mA ● 300 450 µA

LOAD

I

= 50mA ● 0.8 1.5 mA

LOAD

I

= 100mA ● 1.4 2.5 mA

LOAD

I

= 150mA ● 2.2 4.0 mA

LOAD

I

= 300mA ● 6.5 12.0 mA

LOAD

LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD

Adjust Pin Bias Current (Notes 5, 8) TJ = 25°C 50 100 nA
Shutdown Threshold V

Shutdown Pin Current (Note 9) V
Quiescent Current in Shutdown (Note 10) VIN = V
Ripple Rejection VIN – V

Current Limit VIN – V

= Off to On ● 1.20 2.80 V

OUT

V

= On to Off ● 0.25 0.75 V

OUT

= 0V ● 2.0 5.0 µA

SHDN

(NOMINAL) + 1V, V

OUT

= 1V(Avg), V

f

RIPPLE

VIN = V

OUT

= 120Hz, I

= 7V, TJ = 25°C 400 800 mA

OUT

(NOMINAL) + 1.5V, ∆V

OUT

LOAD

RIPPLE

= 150mA

= 1mA, TJ = 25°C 2.950 3.000 3.050 V

OUT

= 1mA, TJ = 25°C 3.250 3.300 3.350 V

OUT

= 1mA, TJ = 25°C 4.925 5.000 5.075 V

OUT

= 1mA, TJ = 25°C 3.695 3.750 3.805 V

OUT

< 300mA ● 2.900 3.000 3.100 V

OUT

< 300mA ● 3.200 3.300 3.400 V

OUT

< 300mA ● 4.850 5.000 5.150 V

OUT

< 300mA ● 3.640 3.750 3.860 V

OUT

= 1mA ● 1.5 20 mV

OUT

= 1mA ● 1.5 20 mV

OUT

= 1mA ● 1.5 20 mV

OUT

= 1mA ● 1.5 20 mV

OUT

= 1mA to 300mA, TJ ≤ 25°C–20–30mV
= 1mA to 300mA, TJ ≤ 25°C–20–30mV
= 1mA to 300mA, TJ ≤ 25°C–25–45mV
= 1mA to 300mA, TJ ≤ 25°C–20–30mV
= 1mA to 300mA, TJ >25°C–20–55mV
= 1mA to 300mA, TJ > 25°C–20–55mV
= 1mA to 300mA, TJ > 25°C–25–75mV
= 1mA to 300mA, TJ > 25°C–20–55mV

= 0V ● 612µA

SHDN

= 0.5V

,5058dB

P–P

= –0.1V ● 320 400 mA

OUT

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LT1521/LT1521-3
LT1521-3.3/LT1521-5

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at TA = 25°C.

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Reverse Leakage Current VIN = –20V, V
Reverse Output Current (Note 11) LT1521-3 V

LT1521-3.3 V
LT1521-5 V
LT1521 (Note 5) V

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

Note 2: The shutdown pin input voltage rating is required for a low
impedance source. Internal protection devices connected to the shutdown
pin will turn on and clamp the pin to approximately 7V or –0.6V. This
range allows the use of 5V logic devices to drive the pin directly. For high
impedance sources or logic running on supply voltages greater than 5.5V,
the maximum current driven into the shutdown pin must be limited to less
than 5mA.

Note 3: For junction temperatures greater than 110°C, a minimum load of
1mA is recommended. For T

> 110°C and I

J

< 1mA, output voltage

OUT

may increase by 1%.
Note 4: Operating conditions are limited by maximum junction

temperature. The regulated output voltage specification will not apply for
all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current, the input voltage
range must be limited.

= 0V ● 1.0 mA

OUT

= 3V, VIN < 3V, TJ = 25°C510µA

OUT

= 3.3V, VIN < 3.3V, TJ = 25°C510µA

OUT

= 5V, VIN < 5V, TJ = 25°C510µA

OUT

= 3.8V, VIN < 3.75V, TJ = 25°C510µA

OUT

Note 5: The LT1521 (adjustable version) is tested and specified with the
adjust pin connected to the output pin.

Note 6: Dropout voltage is the minimum input/output voltage required to
maintain regulation at the specified output current. In dropout the output
voltage will be equal to: (V

IN

– V

Note 7: Ground pin current is tested with V

DROPOUT

)

= V

IN

(nominal) and a

OUT

current source load. This means the device is tested while operating in its
dropout region. This is the worst-case ground pin current. The ground pin
current will decrease slightly at higher input voltages.

Note 8: Adjust pin bias current flows into the adjust pin.
Note 9: Shutdown pin current at V

= 0V flows out of the shutdown

SHDN

pin.
Note 10: Quiescent current in shutdown is equal to the total sum of the

shutdown pin current (2µA) and the ground pin current (4µA).
Note 11: Reverse output current is tested with the input pin grounded and

the output pin forced to the rated output voltage. This current flows into
the output pin and out of the ground pin.

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TYPICAL PERFORMANCE CHARACTERISTICS

Guaranteed Dropout Voltage

0.8
= TEST POINTS

0.7

0.6

0.5

0.4

0.3

DROPOUT VOLTAGE (V)

0.2

0.1

TJ ≤ 125°C

0

50 100 200

0

OUTPUT CURRENT (mA)

TJ ≤ 25°C

150

250

LT1521 • TPC01

300

Dropout Voltage

0.8

0.7

0.6

0.5

0.4

0.3

DROPOUT VOLTAGE (V)

0.2

0.1

0

–25 0 50

–50

TEMPERATURE (°C)

I

I

LOAD

LOAD

= 300mA

= 100mA

I

LOAD

I

LOAD

25

I

LOAD

= 50mA

= 1mA

75 100 125

= 150mA

4

LT1521 • TPC02

Quiescent Current

15.0

12.5

10.0

7.5

5.0

QUIESCENT CURRENT (µA)

2.5

0

–50

VIN = 6V

= ∞

R

L

I

LOAD

–25 0

= 0

25 75

TEMPERATURE (°C)

V

= OPEN

SHDN

V

= 0V

SHDN

50 100 125

LT1521 • TPC03

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1521/LT1521-3

LT1521-3.3/LT1521-5

LT1521-3
Output Voltage

3.08

3.06

3.04

3.02

3.00

2.98

OUTPUT VOLTAGE (V)

2.96

2.94

2.92
–25 0 50

–50

LT1521
Adjust Pin Voltage

3.83
I

= 1mA

LOAD

3.81

3.79

3.77

3.75

3.73

OUTPUT VOLTAGE (V)

3.71

3.69

3.67

–25 0 50

–50

25

TEMPERATURE (°C)

25

TEMPERATURE (°C)

75 100 125

LT1521 • TPC04

75 100 125

LT1521 • TPC07

LT1521-3.3
Output Voltage

3.38
I

= 1mA

OUT

3.36

3.34

3.32

3.30

3.28

OUTPUT VOLTAGE (V)

3.26

3.24

3.22

–25 0 50

–50

LT1521-3
Quiescent Current

50
45
40
35
30
25
20
15

QUIESCENT CURRENT (µA)

10

5
0

213579

0

25

TEMPERATURE (°C)

V

= OPEN

SHDN

V

= 0V

SHDN

6

4

INPUT VOLTAGE (V)

75 100 125

LT1521 • TPC05

TJ = 25°C

=

∞

R

L

8

LT1521 • TPC08

OUTPUT VOLTAGE (V)

10

LT1521-5
Output Voltage

5.08

5.06

5.04

5.02

5.00

4.98

4.96

4.94

4.92
–25 0 50

–50

LT1521-3.3
Quiescent Current

50
45
40
35
30
25
20
15

QUIESCENT CURRENT (µA)

10

5
0

213579

0

25

TEMPERATURE (°C)

6

4

INPUT VOLTAGE (V)

75 100 125

LT1521 • TPC06

TJ = 25°C

=

∞

R

L

8

LT1521 • TPC09

10

LT1521-5
Quiescent Current

50
45
40
35
30
25
20
15

QUIESCENT CURRENT (µA)

10

5
0

213579

0

V

SHDN

V

= 0V

SHDN

6

4

INPUT VOLTAGE (V)

TJ = 25°C

R

=

L

= OPEN

8

LT1521 • TPC10

LT1521
Quiescent Current

50

∞

10

45
40
35
30
25
20
15

QUIESCENT CURRENT (µA)

10

5
0

0

V

SHDN

213579

4

INPUT VOLTAGE (V)

V

SHDN

= 0V

6

TJ = 25°C

= OPEN

=

R

L

8

LT1521 • TPC11

∞

10

LT1521-3
Ground Pin Current

1000

TJ = 25°C

900

*FOR V

800
700
600
500
400
300

GROUND PIN CURRENT (µA)

200
100

0

0

OUT

213579

= 3V

R
I

R

= 120Ω

LOAD

= 25mA*

I

LOAD

R

LOAD

I

LOAD

R

= 3k

LOAD

= 1mA*

I

LOAD

6

4

INPUT VOLTAGE (V)

LOAD

LOAD

= 300Ω

= 10mA*

= 60Ω

= 50mA*

8

LT1521 • TPC12

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10

5