ST LD2985BM18R, LD2985BM25R, LD2985BM28R, LD2985BM30R, LD2985BM31R User Manual

Very low drop and low noise voltage regulator low ESR

capacitors compatible, with inhibit function

Features

■ Very low dropout voltage (280 mV at 150 mA

and 7 mV at 1 mA load)

■ Very low quiescent current (2 mA typ. at 150

mA load and 80 µA at no load)

■ Output current up to 150 mA

■ Logic controlled electronic shutdown

■ Output voltage of 1.8, 2.5, 2.8, 3, 3.1, 3.3, 5 V

■ Internal current and thermal limit

■ Low output noise voltage 30 mVrms

■ Smallest package SOT23-5L

■ Temperature range: - 40°C to 125 °C

Description

LD2985Bxx

SOT23-5L

between bypass pin and GND reduce the noise
to 30 µVrms. Typical application are in cellular
phone, palmtop laptop computer, personal digital
assistant (PDA), personal stereo, camcorder and
camera.

The LD2985Bxx is a 150 mA fixed output voltage
regulator. The ultra low drop voltage and the low
quiescent current make them particularly suitable
for low noise, low power applications, and in
battery powered systems. In sleep mode
quiescent current is less than 1 µA when INHIBIT
pin is pulled low. Shutdown logic control function
is available on pin 3 (TTL compatible). This
means that when the device is used as local
regulator, it is possible to put a part of the board in
standby, decreasing the total power consumption.
An external capacitor, C

= 10 nF, connected

BYP

Table 1. Device summary

Part numbers Order codes Output voltages

LD2985BXX18 LD2985BM18R 1.8 V

LD2985BXX25 LD2985BM25R 2.5 V

LD2985BXX28 LD2985BM28R 2.8 V

LD2985BXX30 LD2985BM30R 3.0 V

LD2985BXX31 LD2985BM31R 3.1 V

LD2985BXX33 LD2985BM33R 3.3 V

LD2985BXX50 LD2985BM50R 5.0 V

February 2012 Doc ID 8189 Rev 12 1/18

www.st.com

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Contents LD2985Bxx

Contents

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

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

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

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6 Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.1 External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.2 Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.3 Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.4 Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.5 Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6.6 Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

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LD2985Bxx Diagram

1 Diagram

Figure 1. Schematic diagram

Doc ID 8189 Rev 12 3/18

Pin configuration LD2985Bxx

2 Pin configuration

Figure 2. Pin connections (top view)

5

12

4

3

SC12360

Table 2. Pin description

Pin n° Symbol Name and function

1 IN Input port

2 GND Ground pin

Control switch ON/OFF. Inhibit is not internally pulled-up; it cannot be left

3 INHIBIT

4Bypass

5 OUT Output port

floating. Disable the device when connected to GND or to a positive
voltage less than 0.18V

Bypass pin: capacitor to be connected to GND in order to improve the
thermal noise performances

Table 3. Thermal data

Symbol Parameter Value Unit

R

thJC

R

thJA

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Thermal resistance junction-case 81 °C/W

Thermal resistance junction-ambient 255 °C/W

LD2985Bxx 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 16 V

INHIBIT input voltage 16 V

Output current Internally limited

Power dissipation Internally limited

Storage temperature range -65 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.

Doc ID 8189 Rev 12 5/18

Electrical characteristics LD2985Bxx

4 Electrical characteristics

TJ = 25 °C, VI = VO + 1 V, IO = 50 mA, V

Table 5. Electrical characteristics

= 2 V, CI = CO = 1 µF, unless otherwise specified.

INH

Symbol Parameter Test conditions Min. Typ. Max. Unit

V

V

V

V

V

V

V

V

V

V

V

V

Operating input voltage 2.5 16 V

OP

V

= 2.5V 1.463 1.5 1.537

I

O

O

O

O

O

O

O

O

O

O

O

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

Output voltage

= 1 to 150mA 1.455 1.545

O

= 1 to 150mA, TJ= -40 to 125°C 1.440 1.560

I

O

V

= 2.8V 1.755 1.8 1.845

I

= 1 to 150mA 1.746 1.854

O

= 1 to 150mA, TJ= -40 to 125°C 1.728 1.872

I

O

V

= 3.5V 2.437 2.5 2.562

I

= 1 to 150mA 2.425 2.575

O

= 1 to 150mA, TJ= -40 to 125°C 2.4 2.6

I

O

V

= 3.5V 2.633 2.7 2.767

I

= 1 to 150mA 2.619 2.781

O

= 1 to 150mA, TJ= -40 to 125°C 2.592 2.808

I

O

V

= 3.8V 2.73 2.8 2.87

I

= 1 to 150mA 2.716 2.884

O

= 1 to 150mA, TJ= -40 to 125°C 2.688 2.912

I

O

V

= 3.85V 2.779 2.85 2.921

I

= 1 to 150mA 2.764 2.935

O

= 1 to 150mA, TJ= -40 to 125°C 2.736 2.964

I

O

V

= 4.0V 2.925 3.0 3.075

I

= 1 to 150mA 2.91 3.09

O

= 1 to 150mA, TJ= -40 to 125°C 2.88 3.12

I

O

V

= 4.1V 3.023 3.1 3.177

I

= 1 to 150mA 3.007 3.193

O

= 1 to 150mA, TJ= -40 to 125°C 2.976 3.224

I

O

V

= 4.2V 3.120 3.2 3.28

I

= 1 to 150mA 3.104 3.296

O

= 1 to 150mA, TJ= -40 to 125°C 3.072 3.328

I

O

V

= 4.3V 3.218 3.3 3.382

I

= 1 to 150mA 3.201 3.399

O

= 1 to 150mA, TJ= -40 to 125°C 3.168 3.432

I

O

V

= 4.5V 3.413 3.5 3.587

I

= 1 to 150mA 3.395 3.605

O

= 1 to 150mA, TJ= -40 to 125°C 3.360 3.640

I

O

VI

VI

VI

VI

VI

VI

VI

VI

VI

VI

VI

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