1 Amp/1.5 Amp/2 Amp Synchronous,

Step-Down DC-to-DC Converters

ADP2105/ADP2106/ADP2107

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibilityis assumedbyAnalogDevicesforitsuse,norforanyinfringements of patents or other

rightsofthirdpartiesthatmayresultfromitsuse.Specificationssubjecttochangewithoutnotice.No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

Fax: 781.461.3113

©2006 Analog Devices, Inc. All rights reserved.

FEATURES

Extremely high 97% efficiency

Ultralow quiescent current: 20 μA

1.2 MHz switching frequency

0.1 μA shutdown supply current

Maximum load current:

ADP2105: 1 A

ADP2106: 1.5 A

ADP2107: 2 A

Input voltage: 2.7 V to 5.5 V

Maximum duty cycle: 100%

Smoothly transitions into low dropout (LDO) mode

Internal synchronous rectifier

Small 16-lead 4 mm × 4 mm LFCSP_VQ package

Optimized for small ceramic output capacitors

Enable/Shutdown logic input

Undervoltage lockout

Soft start

APPLICATIONS

Mobile handsets

PDAs and palmtop computers

Telecommunication/Networking equipment

Set top boxes

Audio/Video consumer electronics

GENERAL DESCRIPTION

The ADP2105/ADP2106/ADP2107 are low quiescent current,

synchronous, step-down dc-to-dc converters in a compact 4 mm ×

4 mm LFCSP_VQ package. At medium-to-high load currents,

these devices use a current-mode, constant-frequency pulse

width modulation (PWM) control scheme for excellent stability

and transient response. To ensure the longest battery life in

portable applications, the ADP2105/ADP2106/ADP2107 use a

pulse frequency modulation (PFM) control scheme under light

load conditions that reduces switching frequency to save power.

The ADP2105/ADP2106/ADP2107 run from input voltages of

2.7 V to 5.5 V, allowing single Li+/Li− polymer cell, multiple

alkaline/NiMH cells, PCMCIA, and other standard power sources.

The output voltage of ADP2105/ADP2106/ADP2107-ADJ is

adjustable from 0.8 V to the input voltage, while the ADP2105/

ADP2106/ADP2107-xx are available in preset output voltage

options of 3.3 V, 1.8 V, 1.5 V, and 1.2 V. Each of these variations is

available in three maximum current levels, 1 A (ADP2105), 1.5 A

(ADP2106), and 2 A (ADP2107). The power switch and synchro-

nous rectifier are integrated for minimal external part count

and high efficiency. During logic-controlled shutdown, the

input is disconnected from the output, and it draws less than

0.1 μA from the input source. Other key features include

undervoltage lockout to prevent deep-battery discharge and

programmable soft start to limit inrush current at startup.

TYPICAL PERFORMANCE CHARACTERISTICS

100

75

0

2000

LOAD CURRENT (mA)

95

90

85

80

200

400

600

800 1000 1200 1400 1600 1800

TYPICAL OPERATING CIRCUIT

ADP2107-ADJ

OFF

EN

SS

LX2

FB

PWIN1

AGND

OUTPUT VOLTAGE = 2.5V

COMP

ON

PGND

IN

GND

GND

GND

NC

GND

LX1

PWIN2

10μF

FB

1nF

70kΩ

120pF

1

2

3

4

12

11

10

9

16

15

14

13

5

6

7

8

2μH

4.7μF

LOAD

0A TO 2A

10μF

10μF

10Ω

0.1μF

NC = NO CONNECT

85kΩ

40kΩ

FB