National Semiconductor LP2957, LP2957A Technical data

LP2957/LP2957A
5V Low-Dropout Regulator for µP Applications

LP2957/LP2957A 5V Low-Dropout Regulator for µP Applications

June 1998

General Description

The LP2957 is a 5V micropower voltage regulator with elec­tronic shutdown, error flag, very low quiescent current
(150 µA typical at 1 mA load), and very low dropout voltage
(470 mV typical at 250 mA load current).

Output can be wired for snap-on/snap-off operation to elimi­nate transitionvoltage states where µP operation may be un­predictable.

Output crowbar (50 mA typical pull-down current) will bring
down the output quickly when the regulator snaps off or
when the shutdown function is activated.

The part has tight line and load regulation (0.04%typical)
and low output temperature coefficient (20 ppm/˚C typical).

The accuracy of the 5V output is guaranteed at room tem­perature and over the full operating temperature range.

The LP2957 is available in the five-lead TO-220 and TO-263
packages.

Package Outline

Bent, Staggered Leads

5-Lead TO-220 (T)

Order Number LP2957AIT or LP2957IT

See NS Package Number T05D

Features

n 5V output within 1.4%over temperature (A grade)
n Easily programmed for snap-on/snap-off output
n Guaranteed 250 mA output current
n Extremely low quiescent current
n Low Input-Output voltage required for regulation
n Reverse battery protection
n Extremely tight line and load regulation
n Very low temperature coefficient
n Current and thermal limiting
n Error flag signals when output is out of regulation

Applications

n High-efficiency linear regulator
n Battery-powered regulator

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Top View

Plastic Surface Mount Package

5-Lead TO-263 (S)

DS011340-17

Top View

DS011340-18

Order Number LP2957AIS or LP2957IS

See NS Package Number TS5B

© 1999 National Semiconductor Corporation DS011340 www.national.com

Side View

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Operating Junction

Temperature Range −40˚C to +125˚C

Storage Temperature Range −65˚C to +150˚C

Lead Temperature

(Soldering, 5 Seconds) 260˚C
Power Dissipation (Note 2) Internally Limited
Input Supply Voltage −20V to +30V
Shutdown Input

−0.3V to +30V

ESD Rating 2 kV

Electrical Characteristics

Limits in standard typeface are for T
less otherwise specified: V

IN

Symbol Parameter Conditions Typical

V

O

Output Voltage 5.0 4.975 5.025 4.950 5.050

Output Voltage
Temperature
Coefficient

Line Regulation V

Load Regulation I

V

IN–VO

Dropout Voltage I
(Note 5) 150 150

I

GND

Ground Pin Current I
(Note 6) 230 230

I

GND

Ground Pin Current I
in Shutdown (Note 6) V

I

GND

Ground Pin Current V
at Dropout (Note 6) I

I

O

Off-State Output V
(Sink) Pulldown Current V
I

O

Output Leakage I
(Off) in Shutdown V
I

LIMIT

Current Limit R

Thermal Regulation (Note 7)

=

25˚C, and limits in boldface type apply over the full operating temperature range. Un-

J

=

6V, I

=

L

1 mA, C

L

1mA≤I

=

2.2 µF, V

≤250 mA 5.0 4.930 5.070 4.880 5.120

L

=

3V.

SD

(Note 3)

=

6V to 30V 0.03 0.10 0.20

IN

=

1mAto250mA

L

=

I

0.1 mA to 1 mA

L

(Note 4)

=

1 mA 60 100 100 mV

L

=

I

50 mA 240 300 300

L

=

I

100 mA 310 400 400

L

=

I

250 mA 470 600 600

L

=

1 mA 150 200 200 µA

L

=

I

50 mA 1.1 2 2 mA

L

=

I

100 mA 3 6 6

L

=

I

250 mA 16 28 28

L

=

0 130 180 180 µA

L

=

0.4V 200 200

SD

=

4.5V 180 230 230 µA

IN

=

0.1 mA 250 250

L

=

5.3V 50 30 30 mA

IN
O

(SD IN)

IN

=

L

=

=

=

5V, V

0.4V 20 20

SD

≥ 1 µA 3 10 10 µA

30V, V

=

0V 20 20

OUT

1Ω 400 500 500 mA

LP2957AI LP2957I

Min Max Min Max

Units

20 100 150 ppm/˚C

0.20 0.40

%

0.16 0.20

0.04

0.20 0.30

%

420 420

520 520

800 800

2.5 2.5

88

33 33

530 530

0.05 0.2 0.2

%

V(Note 9) 4.940 5.060 4.900 5.100

/W

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Electrical Characteristics (Continued)

Limits in standard typeface are for T
less otherwise specified: V

IN

Symbol Parameter Conditions Typical

e

n

Output Noise Voltage C
(10 Hz to 100 kHz)

=

100 mA

I

L

SHUTDOWN INPUT

VSD(ON) Output Turn-On 1.155 1.305 1.155 1.305 V

=

25˚C, and limits in boldface type apply over the full operating temperature range. Un-

J

=

6V, I

=

L

1 mA, C

=

2.2 µF, V

L

=

2.2 µF 500

L

=

C

33 µF 320

L

=

3V.

SD

LP2957AI LP2957I

Min Max Min Max

Units

RMS

µV

Typical Performance Characteristics Unless otherwise specified: V

=

3V, T

=

25˚C

A

Ground Pin Current

Ground Pin Current
vs Load

SD

Ground Pin Current

=

=

6V, I

L

1 mA, C

IN

=

L

2.2 µF, V

Ground Pin Current

Ripple Rejection

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Ground Pin Current

Ripple Rejection

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DS011340-26

DS011340-21

Output Noise Voltage

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Ripple Rejection

DS011340-27

Line Transient Response

DS011340-28

Line Transient Response

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DS011340-29

Output Impedance

DS011340-30

Typical Performance Characteristics Unless otherwise specified: V

=

3V, T

A

=

25˚C (Continued)

V

SD

=

=

6V, I

IN

L

1 mA, C

L

=

2.2 µF,

Load Transient
Response

Enable Transient

DS011340-31

DS011340-34

Load Transient
Response

Enable Transient

DS011340-32

DS011340-35

Dropout
Characteristics

DS011340-33

Short-Circuit Output
Current and Maximum
Output Current

DS011340-36

Thermal Regulation

DS011340-37

Error Output
Sink Current

DS011340-38

Dropout Detection
Threshold Voltages

DS011340-39

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