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600 mA/1000 mA, 2.5 MHz Buck-Boost
DC-to-DC Converters
ADP2503/ADP2504
FEATURES
1 mm height profile
Compact PCB footprint
Seamless transition between modes
38 μA typical quiescent current
2.5 MHz operation enables 1.5 μH inductor
Input voltage: 2.3 V to 5.5 V
Fixed output voltage: 2.8 V to 5.0 V
Adjustable model output voltage range: 2.8 V to 5.5 V
600 mA (ADP2503) and 1000 mA (ADP2504) output options
Boost converter configuration with load disconnect
SYNC pin with three different modes
Power save mode (PSM) for improved light load efficiency
Forced fixed frequency operation mode
Synchronization with external clock
Internal compensation
Soft start
Enable/shutdown logic input
Overtemperature protection
Short-circuit protection
Undervoltage lockout protection
Small 10-lead 3 mm × 3 mm LFCSP (QFN) package
GENERAL DESCRIPTION
The ADP2503/ADP2504 are high efficiency, low quiescent current
step-up/step-down dc-to-dc converters that can operate at input
voltages greater than, less than, or equal to the regulated output
voltage. The power switches and synchronous rectifiers are
internal to minimize external part count. At high load currents,
the ADP2503/ADP2504 use a current-mode, fixed frequency
pulse-width modulation (PWM) control scheme for optimal
stability and transient response. To ensure the longest battery life
in portable applications, the ADP2503/ADP2504 have an optional
power save mode that reduces the switching frequency under
light load conditions. For wireless and other low noise applica-
tions where variable frequency power save mode may cause
interference, the logic control input sync forces fixed frequency
PWM operation under all load conditions.
The ADP2503/ADP2504 can run from input voltages between
2.3 V and 5.5 V, allowing single lithium or lithium polymer cell,
multiple alkaline or NiMH cells, PCMCIA, USB, and other stan-
dard power sources. The ADP2503/ADP2504 have fixed output
options, or using the adjustable model, the output voltage can
be programmed through an external resistor divider. Compensa-
tion is internal to minimize the number of external components.
During logic-controlled shutdown, the input is disconnected
from the output and draws less than 1 μA from the input source.
Operating as boost converters, the ADP2503/ADP2504 feature
a true load disconnect function that isolates the load from the
power source. Other key features include undervoltage lockout
to prevent deep battery discharge, and soft start to prevent input
current overshoot at startup.
APPLICATIONS
Wireless handsets
Digital cameras/portable audio players
Miniature hard disk power supplies
USB powered devices
TYPICAL APPLICATION CIRCUIT
1.5µH
SW1
V
IN
2.3V TO 5.5V
SW2
V
OUT
2.8V TO 5V
ADP2503/ADP2504
PVIN
VIN
VOUT
FB
10µF
22µF
SYNC
1
EN
ON
OFF
1
ALLOWS
07475-001
AGND PGND
THE ADP2503/ADP2504 TO OPERATE IN
THREE DIFFERENT MODES.
Figure 1.
Rev. B
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.
Trademarks and registered trademarks are the property of their respective owners.
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 ©2008–2010 Analog Devices, Inc. All rights reserved.
ADP2503/ADP2504
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Typical Application Circuit ............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
Thermal Data ................................................................................ 4
Thermal Resistance ...................................................................... 4
ESD Caution .................................................................................. 4
Pin Configuration and Function Descriptions ............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ...................................................................... 11
Power Save Mode........................................................................ 11
Soft Start ...................................................................................... 11
SYNC Function........................................................................... 11
Enable........................................................................................... 11
Undervoltage Lockout ............................................................... 12
Thermal Shutdown .................................................................... 12
Short-Circuit Protection............................................................ 12
Reverse Current Limit ............................................................... 12
Applications Information .............................................................. 13
Inductor Selection ...................................................................... 13
Output Voltage Programming .................................................. 14
PCB Layout Guidelines .................................................................. 15
Outline Dimensions ....................................................................... 16
Ordering Guide .......................................................................... 16
REVISION HISTORY
6/10—Rev. A to Rev. B
Changes to Ordering Guide .......................................................... 16
8/09—Rev. 0 to Rev. A
Changes to Features Section, Figure 1, and General Description
Section ................................................................................................ 1
Changes to Feedback Voltage Parameter and EN, SYNC
Leakage Current Parameter, Table 1 .............................................. 3
Changes to Table 2 and Thermal Resistance Section................... 4
Added Thermal Data Section ......................................................... 4
Changes to Figure 2 and Table 4 ..................................................... 5
Changes to Figure 12.........................................................................7
Changes to Figure 17.........................................................................8
Changes to SYNC Function Section ............................................ 11
Changes to Undervoltage Lockout Section ................................. 12
Changes to Table 6.......................................................................... 13
Added Output Voltage Programming Section ........................... 14
Added Figure 30; Renumbered Sequentially .............................. 14
Changes to Ordering Guide .......................................................... 16
10/08—Revision 0: Initial Version
Rev. B | Page 2 of 16
ADP2503/ADP2504
SPECIFICATIONS
V
IN
= 3.6 V, V
OUT
= 3.3 V, @ T
A
= T
J
= −40°C to +125°C for minimum/maximum specifications and T
A
= 25°C for typical specifications,
unless otherwise noted.
1
Table 1.
Parameters
INPUT CHARACTERISTICS
Input Voltage Range
Undervoltage Lockout Threshold
OUTPUT CHARACTERISTICS
Output Voltage Range
Feedback Impedance
Feedback Voltage
Output Voltage Initial Accuracy
Load and Line Regulation
CURRENT CHARACTERISTICS
Quiescent Current (V
IN
)
Shutdown Current
SWITCH CHARACTERISTICS
N-Channel Switches
P-Channel Switches
P-Channel Leakage
Switch Current Limit
ADP2504
ADP2503
Reverse Current Limit
OSCILLATOR AND STARTUP
Oscillator Frequency
On Time PMOS1 (Buck Mode)
On Time NMOS2 (Boost Mode)
SYNC Clock Frequency
SYNC Clock Minimum Off Time
LOGIC LEVEL CHARACTERISTICS
EN, SYNC Input High Threshold
EN, SYNC Input Low Threshold
EN, SYNC Leakage Current
THERMAL CHARACTERISTICS
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
1
Conditions
Min
2.3
2.15
2.10
2.8
Typ
Max
5.5
2.25
2.20
5.5
Unit
V
V
V
V
kΩ
mV
%
%
%
μA
μA
mΩ
mΩ
μA
A
A
A
MHz
ns
ns
MHz
ns
V
V
μA
°C
°C
V
IN
rising
V
IN
falling
2.20
2.14
ADP2503/ADP2504 adjustable output (PWM operation, no load)
ADP2503/ADP2504 fixed output (PWM operation, no load)
V
IN
= 2.3 V to 3.6 V, I
LOAD
= 0 mA to 500 mA, forced PWM mode
V
IN
= 2.3 V to 5.5 V, I
LOAD
= 0 mA to 500 mA, forced PWM mode
I
OUT
= 0 mA, V
IN
= EN = 3.6 V, device not switching
T
A
= T
J
= −40°C to +125°C
V
IN
= 3.6 V
V
IN
= V
OUT
= 3.6 V
T
J
= −40°C to +125°C
490
−2
450
500
510
+2
0.5
0.6
50
1
38
0.2
150
150
1
1.3
1.0
2.0
1.4
1.1
2.5
2.9
200
2.8
Minimum duty cycle = 30%
Maximum duty cycle = 50% (×2)
2.1
130
2.2
160
1.2
V
EN
= V
IN
, V
SYNC
= V
IN
−1
+0.1
150
25
0.4
+1
All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC).
Rev. B | Page 3 of 16
ADP2503/ADP2504
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
PVIN, VIN, SW1, SW2, VOUT, SYNC, EN, FB
PGND to AGND
Operating Ambient Temperature Range
Operating Junction Temperature Range
Storage Temperature Range
Soldering Conditions
ESD Human Body Model
ESD Charged Device Model
ESD Machine Model
Rating
−0.3 V to +6 V
−0.3 V to 0.3 V
−40°C to +125°C
−40°C to +125°C
−65°C to +150°C
JEDEC J-STD-020
±2000 V
±1500 V
±100 V
θ
JA
of the package is based on modeling and calculation using a
4-layer board. The junction-to-ambient thermal resistance is
highly dependent on the application and board layout. In applica-
tions where high maximum power dissipation exists, close
attention to thermal board design is required. The value of θ
JA
may vary, depending on PCB material, layout, and environmental
conditions. The specified values of θ
JA
are based on a 4-layer,
4 inch × 3 inch circuit board. Refer to JEDEC JESD 51-9 for
detailed information on the board construction.
THERMAL RESISTANCE
θ
JA
are specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3.
Package Type
10-Lead LFCSP (QFN)
θ
JA
84
Unit
°C/W
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
THERMAL DATA
Absolute maximum ratings apply individually only, not in
combination.
The ADP2503/ADP2504 can be damaged when the junction
temperature limits are exceeded. Monitoring ambient tempera-
ture (T
A
) does not guarantee that the junction temperature (T
J
)
is within the specified temperature limits. In applications with
high power dissipation and poor thermal resistance, the maximum
ambient temperature may have to be derated. In applications
with moderate power dissipation and low PCB thermal resis-
tance, the maximum ambient temperature can exceed the
maximum limit as long as the junction temperature is within
specification limits. T
J
of the device is dependent on T
A
, the
power dissipation (P
D
) of the device, and the junction-to-
ambient thermal resistance (θ
JA
) of the package. Maximum
T
J
is calculated from T
A
and P
D
using the following formula:
T
J
=
T
A
+ (P
D
× θ
JA
)
Rev. B | Page 4 of 16
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