ST LD2981ABM25TR, LD2981ABU25TR, LD2981CU25TR, LD2981ABM30TR, LD2981ABU30TR User Manual

Ultra low drop voltage regulators with inhibit

low ESR output capacitors compatible

Features

■ Stable with low ESR ceramic capacitors

■ Ultra low dropout voltage (0.17 V typ. at 100

mA load, 7 mV typ. at 1 mA load)

■ Very low quiescent current (80 µA typ. at no

load in on mode; max 1 µA in off mode)

■ Guaranteed output current up to 100mA

■ Logic-controlled electronic shutdown

■ Output voltage of 2.5; 3.0; 3.3; 5.0 V

■ Internal current and thermal limit

■ ± 0.75 % tolerance output voltage available (A

version)

■ Output low noise voltage 160 µV

■

Temperature range: -40 to 125 °C

■ Smallest package SOT23-5L and SOT-89

■ Fast dynamic response to line and load

changes

RMS

LD2981ABxx

LD2981Cxx

SOT-89SOT23-5L

logic control function is available on pin n° 3 (TTL
compatible). This means that when thedevice is
used as local regulator, it is possible to put a part
of the board in standby, decreasing the total
power consumption. The LD2981AB/C is
designed to work with low ESR ceramic capacitor.
Typical applications are in cellular phone,
palmtop/laptop computer, personal digital
assistant (PDA), personal stereo, camcorder and
camera.

Description

The LD2981AB/C series are 100 mA fixed-output
voltage regulator. The low drop-voltage and the
ultra low quiescent current make them suitable for
low noise, low power applications and in battery
powered systems.

The quiescent current in sleep mode is less than
1 µA when INHIBIT pin is pulled low. Shutdown

Table 1. Device summary

Part numbers

Output voltage

AB Versio n C Vers ion

LD2981ABXX25 LD2981CXX25 2.5 V

LD2981ABXX30 LD2981CXX30 3.0 V

LD2981ABXX33 LD2981CXX33 3.3 V

LD2981ABXX50 LD2981CXX50 5.0 V

July 2008 Rev 14 1/23

www.st.com

23

LD2981ABxx - LD2981Cxx

Contents

1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

6 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7 Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.1 External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.2 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.3 Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.4 Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.5 Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

7.6 Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

9 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

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LD2981ABxx - LD2981Cxx Diagram

1 Diagram

Figure 1. Schematic diagram

3/23

Pin configuration LD2981ABxx - LD2981Cxx

2 Pin configuration

Figure 2. Pin connections (top view)

SOT23-5L

SOT-89

Table 2. Pin description

Pin n°

SOT23-5L

13V

2 2 GND Ground pin

3INHIBIT

4 NC Not connected

51V

Pin n°

SOT-89

Symbol Name and function

IN

Input port

Control switch ON/OFF. Inhibit is not internally pulled-up; it cannot be
left floating. Disable the device when connected to GND or to a
positive voltage less than 0.18 V

OUT

Output port

Table 3. Thermal data

Symbol Parameter SOT23-5L SOT-89 Unit

R

R

thJC

thJA

Thermal resistance junction-case 81 15 °C/W

Thermal resistance junction-ambient 255 110 °C/W

4/23

LD2981ABxx - LD2981Cxx Maximum ratings

3 Maximum ratings

Table 4. Absolute maximum ratings

Symbol Parameter Value Unit

T

V

T

V

INH

I

O

P

STG

OP

I

D

DC input voltage -0.3 to 16 V

INHIBIT input voltage -0.3 to 16 V

Output current Internally limited

Power dissipation Internally limited

Storage temperature range -55 to 150 °C

Operating junction temperature range -40 to 125 °C

Note: Absolute maximum ratings are those values beyond which damage to the device may occur.

Functional operation under these condition is not implied.

5/23

Typical application LD2981ABxx - LD2981Cxx

4 Typical application

Figure 3. Application circuit

Note: Inhibit pin is not internally pulled-up then it must not be left floating. Disable the device when

connected to GND or to a positive voltage less than 0.18 V.

6/23

LD2981ABxx - LD2981Cxx Electrical characteristics

5 Electrical characteristics

Table 5. Electrical characteristics for LD2981AB (TJ = 25 °C, VI = V

C

= 2.2 µF (X7R), IO = 1 mA, V

O

= 2 V, unless otherwise specified).

INH

O(NOM)

+1 V, CI = 1 µF (X7R),

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

ΔV

Operating input voltage 2.5 16 V

OP

I

= 1 mA 2.481 2.5 2.518

O

V

O

V

O

V

O

V

O

V

O

V

O

V

O

V

O

V

O

V

O

V

O

O

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Line regulation

= 1 to 100 mA 2.475 2.525

O

= 1 to 100 mA, TJ= -40 to 125°C 2.437 2.562

I

O

I

= 1 mA 2.828 2.85 2.872

O

= 1 to 100 mA 2.822 2.878

O

= 1 to 100 mA, TJ= -40 to 125°C 2.779 2.921

I

O

I

= 1 mA 2.977 3 3.023

O

= 1 to 100 mA 2.970 3.030

O

= 1 to 100 mA, TJ= -40 to 125°C 2.925 3.075

I

O

I

= 1 mA 3.176 3.2 3.224

O

= 1 to 100 mA 3.168 3.232

O

= 1 to 100 mA, TJ= -40 to 125°C 3.12 3.28

I

O

I

= 1 mA 3.275 3.3 3.325

O

= 1 to 100 mA 3.267 3.333

O

= 1 to 100 mA, TJ= -40 to 125°C 3.217 3.383

I

O

I

= 1 mA 3.573 3.6 3.627

O

= 1 to 100 mA 3.564 3.636

O

= 1 to 100 mA, TJ= -40 to 125°C 3.510 3.690

I

O

I

= 1 mA 3.771 3.8 3.829

O

= 1 to 100 mA 3.762 3.838

O

= 1 to 100 mA, TJ= -40 to 125°C 3.705 3.895

I

O

I

= 1 mA 3.97 4 4.03

O

= 1 to 100 mA 3.96 4.04

O

= 1 to 100 mA, TJ= -40 to 125°C 3.9 4.1

I

O

I

= 1 mA 4.664 4.7 4.735

O

= 1 to 100 mA 4.653 4.747

O

= 1 to 100 mA, TJ= -40 to 125°C 4.582 4.817

I

O

I

= 1 mA 4.813 4.85 4.887

O

= 1 to 100 mA 4.801 4.899

O

= 1 to 100 mA, TJ= -40 to 125°C 4.729 4.971

I

O

I

= 1 mA 4.962 5 5.038

O

= 1 to 100 mA 4.950 5.050

O

= 1 to 100 mA, TJ= -40 to 125°C 4.875 5.125

I

O

V

T

+ 1 < VIN < 16 V, IO = 1 mA 0.003 0.014

O(NOM)

= -40 to 125°C 0.032

J

%/V

VI

VI

VI

VI

VI

VI

VI

VI

VI

VI

VI

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