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ADP2105 Converters Datasheet |
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| Part Number | ADP2105 |
| Description | (ADP2105 - ADP2107) Step-Down DC-to-DC Converters |
| Manufacture | Analog Devices |
| Total Page | 30 Pages |
| Datasheet |
www.DataSheet4U.com
1 Amp/1.5 Amp/2 Amp Synchronous,
Step-Down DC-to-DC Converters
ADP2105/ADP2106/ADP2107
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
Output voltage: 0.8 V to VIN
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
TYPICAL PERFORMANCE CHARACTERISTICS
100
VIN = 3.3V
95
VIN = 3.6V
VOUT = 2.5V
90
VIN = 5V
85
80
75
0 200 400 600 800 1000 1200 1400 1600 1800 2000
LOAD CURRENT (mA)
Figure 1. Efficiency vs. Load Current for the ADP2107 with VOUT = 2.5 V
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 OPERATING CIRCUIT
0.1μF 10Ω
VIN INPUT VOLTAGE = 2.7V TO 5.5V
10μF
FB
ON
OFF
16
FB
1 EN
15
GND
14 13
IN PWIN1
LX2 12
OUTPUT VOLTAGE = 2.5V
2 GND
PGND 11
ADP2107-ADJ
3 GND
LX1 10
4 GND
PWIN2 9 VIN
2μH
85kΩ
FB
40kΩ
COMP SS AGND NC
5678
10μF
10μF 4.7μF
LOAD
0A TO 2A
70kΩ
1nF
120pF
NC = NO CONNECT
Figure 2. Circuit Configuration of ADP2107 with VOUT = 2.5 V
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. 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.
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ADP2105/ADP2106/ADP2107
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Typical Performance Characteristics ............................................. 1
Typical Operating Circuit................................................................ 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
Boundary Condition.................................................................... 5
ESD Caution.................................................................................. 5
Pin Configuration and Function Descriptions............................. 6
Typical Performance Characteristics ............................................. 7
Theory of Operation ...................................................................... 12
Control Scheme .......................................................................... 12
PWM Mode Operation.............................................................. 12
PFM Mode Operation................................................................ 12
Pulse-Skipping Threshold ......................................................... 12
100% Duty Cycle Operation (LDO Mode) ............................. 12
Slope Compensation .................................................................. 13
Features ........................................................................................ 13
Applications Information .............................................................. 15
External Component Selection................................................. 15
REVISION HISTORY
7/06—Revision 0: Initial Version
Setting the Output Voltage........................................................ 15
Inductor Selection ...................................................................... 16
Output Capacitor Selection....................................................... 17
Input Capacitor Selection.......................................................... 17
Input Filter................................................................................... 18
Soft Start ...................................................................................... 18
Loop Compensation .................................................................. 18
Bode Plots.................................................................................... 19
Load Transient Response .......................................................... 20
Efficiency Considerations ......................................................... 21
Thermal Considerations............................................................ 21
Design Example.......................................................................... 22
External Component Recommendations.................................... 24
Circuit Board Layout Recommendations ................................... 26
Evaluation Board ............................................................................ 27
Evaluation Board Schematic (ADP2107-1.8V)...................... 27
Recommended PCB Board Layout
(Evaluation Board Layout)........................................................ 27
Application Circuits ....................................................................... 29
Outline Dimensions ....................................................................... 31
Ordering Guide .......................................................................... 31
Rev. 0 | Page 2 of 32
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| Features | www.DataSheet4U.com 1 Amp/1.5 Amp/2 Amp Synchronous, Step-Down DC-to-DC Conver ters ADP2105/ADP2106/ADP2107 FEATURES E xtremely high 97% efficiency Ultralow q uiescent current: 20 μA 1.2 MHz switch ing frequency 0.1 μA shutdown supply c urrent Maximum load current: ADP2105: 1 A ADP2106: 1.5 A ADP2107: 2 A Input vo ltage: 2.7 V to 5.5 V Output voltage: 0 .8 V to VIN Maximum duty cycle: 100% Sm oothly transitions into low dropout (LD O) mode Internal synchronous rectifier Small 16-lead 4 mm × 4 mm LFCSP_VQ pac kage Optimized for small ceramic output capacitors Enable/Shutdown logic input Undervoltage lockout Soft start GENER AL DESCRIPTION The ADP2105/ADP2106/ADP2 107 are low quiescent current, synchron ous, 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-f requency pulse width modulation (PWM) c ontrol scheme for excellent stability a nd transient response. To ensure the longest battery life in portab. |
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