ANALOG DEVICES ADP2121 Service Manual
500 mA, 6 MHz, Synchronous
www.BDTIC.com/ADI
Preliminary Technical Data
FEATURES
92 % peak efficiency
6 MHz operating frequency
38 µA (typical) no load quiescent current in PFM mode
1.80 V, 1.82 V, 1.85V, 1.875V fixed output voltage
500 mA continuous output current
Input voltage :2.3 V to 5.5 V
0.28 µA (typical) shutdown supply current
Automatic power-saving mode
Compatible with tiny multilayer inductors
Internal synchronous rectifier
Internal compensation
Internal soft start
Output to ground short circuit protection
Current-limit protection
Enable/shutdown logic input
Undervoltage lockout
Thermal shutdown
Ultra small 6-ball 1.17 mm
APPLICATIONS
Mobile phones
Digital cameras
Digital audio
Portable equipment
1-cell Li+/Li-polymer and 3-cell alkaline/nickel
2
WLCSP
Step-Down, DC-to-DC Converter
ADP2121
GENERAL DESCRIPTION
The ADP2121 is a high frequency, low quiescent current, stepdown, dc-to-dc converter optimized for portable applications in
which board area and battery life are critical constraints. Fixed
frequency operation at 6 MHz enables the use of tiny ceramic
inductors and capacitors. Additionally the synchronous rectification
improves efficiency and results in fewer external components. At
high load currents, the device uses a voltage regulating pulse-width
modulation (PWM) mode that maintains a constant frequency
with excellent stability and transient response. At light load
conditions, the ADP2121 can automatically enter a power saving
mode that utilizes pulse-frequency modulation (PFM) to reduce
the effective switching frequency and ensure the longest battery
life in portable applications. During logic controlled shutdown
(EN = 0), the input is disconnected from the output and draws less
than 0.28 A (typical) from the source.
The ADP2121 has an input voltage range of 2.3 V to 5.5 V allowing the
use of a single Li+/Li-polymer cell, multiple alkaline/Ni-MH cell,
PCMCIA, and other standard power sources. The converter is
internally compensated to minimize external components, and its 1.80
V, 1.82 V, 1.85 V, or 1.875 V fixed output can source up to 500 mA.
Other key features include undervoltage lockout (UVLO) to prevent
deep-battery discharge and soft start to prevent input current
overshoot at startup.
TYPICAL APPLICATION CIRCUIT
Figure 1. Circuit Configuration of ADP2121
OUTPUT VOLTAGE OPTIONS
Table 1.
Input Voltage
Range (V)
2.3 - 5.5 100 1.800, 1.850, 1.875
2.3 - 5.5 300 1.820
Rev. PrA
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.
Maximum Start-
up Time (s)
Fixed Output
Voltage (V)
TYPICAL PERFORMANCE
10 0 %
90%
80%
70%
60%
50%
40%
Efficiency
30%
20%
10 %
0%
0 .1 1 10 10 0 10 0 0
Figure 2. Efficiency vs. Load Current (V
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 Analog Devices, Inc. All rights reserved.
Load C urre nt ( mA )
= 3.6 V, V
IN
= 1.82 V, Auto Mode)
OUT
ADP2121 Preliminary Technical Data
www.BDTIC.com/ADI
TABLE OF CONTENTS
Features.............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Typical Application Circuit ............................................................. 1
Typical Performance......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
Thermal Resistance ...................................................................... 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Typical Performance Characteristics ............................................. 6
REVISION HISTORY
11/08—Revision PrA: Preliminary Version
Theory of Operation .........................................................................8
Overview ........................................................................................8
Mode Selection ..............................................................................8
Enable/Shutdown..........................................................................9
Internal Control Features.............................................................9
Applications Information.............................................................. 11
Inductor Selection...................................................................... 11
Input Capacitor Selection.......................................................... 11
Output Capacitor Selection ...................................................... 11
PCB Layout Guide.......................................................................... 13
Outline Dimensions....................................................................... 14
Ordering Guide .......................................................................... 14
Rev. PrA | Page 2 of 14
Preliminary Technical Data ADP2121
www.BDTIC.com/ADI
SPECIFICATIONS1
VIN = EN = 3.6 V, all values are at TA = 25°C.
Table 2.
Parameters Conditions Min Typ Max Unit
SUPPLY
Input Voltage Range I
I
Quiescent Current VIN = 3.6 V (PFM mode), no load, TA = 85°C 38 55 µA
V
Shutdown Current VEN = 0 V 0.28 0.5 µA
UNDERVOLTAGE LOCKOUT
Undervoltage Lockout Threshold VIN rising 2.2 V
V
OUTPUT
Continuous Output Current VIN = 2.3 V 400 mA
V
2
Feedback Bias Current VFB = 1.8 V 3.8 µA
SWITCHING CHARACTERISTICS
)
DSon
SW Leakage Current VIN = 5.5 V, V
SW Current Limit P-channel switch 850 1000 1150 mA
Oscillator Frequency 5.4 6 6.6 MHz
EFFICIENCY (VIN = 3.6 V, V
= 1.82 V) L = 0.47 H, C
OUT
I
I
I
I
I
EN/MODE INPUT LOGIC
High Threshold Voltage 1.2 V
Low Threshold Voltage 0.4 V
Leakage Current VEN = V
SOFT START
3
C
Soft Start Period V
THERMAL SHUTDOWN
Thermal Shutdown Threshold 150 °C
Thermal Shutdown Hysteresis 30 °C
= 0 mA to 400 mA 2.3 5.5 V
LOAD
= 0 mA to 500 mA 2.5 5.5
LOAD
= 3.6 V (PWM mode), no load 10 mA
IN
falling 1.8 V
IN
= 2.5 V to 5.5V 500 mA
IN
Auto mode - 2% V
PWM mode - 2% V
+ 3% V Output Accuracy (1.82 V, VIN = 3.6)
NOM
+ 3% V
NOM
P-channel switch 225 440 m SW On Resistance (R
N-channel synchronous rectifier 290 810 m
= 0 V, 5.5 V 1 µA
SW
= 4.7 F
OUT
= 10 mA (PFM mode) 79 %
LOAD
= 50 mA (PFM mode) 81 %
LOAD
= 150 mA (PWM mode) 87 %
LOAD
= 250 mA (PWM mode) 89 %
LOAD
= 500 mA (PWM mode) 89 %
LOAD
= 0.5 V, 5.5 V 0.01 1 µA
MODE
= 4.7 F, VIN = 3.6 V (time from EN = 0 to stable
OUT
V
)
OUT
= 1.82 V
OUT
V
= 1.8 V, 1.85 V, 1.875 V
OUT
270
80
300
100
µs
µs
1
All limits are subject to change upon final temperature characterization and release.
2
Transients not included in voltage accuracy specifications. For PFM mode, the V
3
Guaranteed by design.
accuracy specification is for the lower point of the ripple.
OUT
Rev. PrA | Page 3 of 14
ADP2121 Preliminary Technical Data
www.BDTIC.com/ADI
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
VIN −0.3 V to +6 V
VEN/V
VFB/VSW −0.3 V to VIN + 0.2 V
Operating Ambient Temperature –40°C to +85°C
Operating Junction Temperature –40°C to + 125°C @ 500 mA
Storage Temperature –45°C to +150°C
Soldering (10 sec) 300°C
Vapor Phase (60 sec) 215°C
Infrared (15 sec) 220°C
ESD (electrostatic discharge)
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.
−0.3 V to +6 V
MODE
Machine Model −100 V to +100 V
Human Body Model −2000 V to +2000 V
Charged Device Model −500 V to +500 V
THERMAL RESISTANCE
The thermal resistance of the system, θJA, is specified for the
worst-case conditions, that is, a device soldered in a circuit
board for surface-mount packages. The junction-to-ambient
thermal resistance is highly dependent on the application and
board layout. In applications where high maximum power
dissipation exists, attention to thermal board design is required.
The value of θ
and environmental conditions.
Table 4.
Package Type θ
6-Ball WLCSP
2-Layer Board 105 °C/W
4-Layer Board 198 °C/W
Maximum Power Dissipation
2-Layer Board 380 mW
4-Layer Board 202 mW
may vary, depending on PCB material, layout,
JA
Unit
JA
ESD CAUTION
Rev. PrA | Page 4 of 14
Preliminary Technical Data ADP2121
www.BDTIC.com/ADI
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
BALLA1
INDICATOR
1
2
MODE VIN
A
SW
B
C
(BALL SIDE DOW N)
(BUMPS ON OPPOSITE SIDE)
Figure 3. Pin Configuration
Table 5. Pin Function Descriptions
Pin No. Mnemonic Description
A1 MODE Mode Select. This pin toggles between auto (PFM and PWM switching) and PWM modes. Set MODE low to allow
the part to operate in auto mode. Pull MODE high to force the part to operate in PWM mode.
B1 SW Switch Node.
C1 FB Feedback Divider Input. Connect the output capacitor from FB to GND to set the output voltage ripple and to
complete the control loop.
A2 VIN Power Supply Input.
B2 EN Enable. Pull this pin high to enable the part. Set this pin low to disable the part. Do not leave this pin floating.
C2 GND Ground Pin.
EN
FB GND
TOP VIEW
Not to Scale
07407-003
Rev. PrA | Page 5 of 14
Loading...