Compact, 800 mA, 3 MHz, Step-Down DC-to-DC Converter Data Sheet ADP2138/ADP2139 FEATURES GENERAL DESCRIPTION Input voltage: 2.3 V to 5.5 V The ADP2138 and ADP2139 are high efficiency, low quiescent Peak efficiency: 95% current, synchronous step-down dc-to-dc converters. The 3 MHz fixed frequency operation ADP2139 has the additional feature of an internal discharge Typical quiescent current: 24 A switch. The total solution requires only three tiny external Very small solution size components. When the MODE pin is set high, the buck 6-lead, 1 mm 1.5 mm WLCSP package regulator operates in forced PWM mode, which provides low Fast load and line transient response peak-to-peak ripple for power supply noise sensitive loads at 100% duty cycle low dropout mode the expense of light load efficiency. When the MODE pin is set Internal synchronous rectifier, compensation, and soft start low, the buck regulator automatically switches operating modes, Current overload and thermal shutdown protections depending on the load current level. At higher output loads, the Ultralow shutdown current: 0.2 A (typical) buck regulator operates in PWM mode. When the load current Forced PWM and automatic PWM/PSM modes falls below a predefined threshold, the regulator operates in power Supported by ADIsimPower design tool save mode (PSM), improving light load efficiency. APPLICATIONS The ADP2138/ADP2139 operate on input voltages of 2.3 V to 5.5 V, which allows for single lithium or lithium polymer cell, PDAs and palmtop computers multiple alkaline or NiMH cell, PCMCIA, USB, and other Wireless handsets standard power sources. The maximum load current of 800 mA Digital audio, portable media players is achievable across the input voltage range. Digital cameras, GPS navigation units The ADP2138/ADP2139 are available in fixed output voltages of 3.3 V, 3.0 V, 2.8 V, 2.5 V, 1.8 V, 1.5 V, 1.2 V, 1.0 V, and 0.8 V. All versions include an internal power switch and synchronous rect- ifier for minimal external part count and high efficiency. The ADP2138/ADP2139 have internal soft start and they are internally compensated. During logic controlled shutdown, the input is disconnected from the output and the ADP2138/ADP2139 draw 0.2 A (typical) from the input source. Other key features include undervoltage lockout to prevent deep battery discharge, and soft start to prevent input current over- shoot at startup. The ADP2138/ADP2139 are available in a 6-ball wafer level chip scale package (WLCSP). TYPICAL APPLICATIONS CIRCUIT 1.0H V 2.3V TO 5.5V OUT VIN SW 4.7F 4.7F ADP2138/ ADP2139 ON EN VOUT OFF FORCE PWM MODE AUTO GND Figure 1. Rev. C Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. 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Technical Support www.analog.com 09496-001ADP2138/ADP2139 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Short-Circuit Protection............................................................ 12 Applications ....................................................................................... 1 Undervoltage Lockout ............................................................... 12 General Description ......................................................................... 1 Thermal Protection .................................................................... 12 Typical Applications Circuit ............................................................ 1 Soft Start ...................................................................................... 12 Revision History ............................................................................... 2 Current Limit .............................................................................. 12 Specifications ..................................................................................... 3 100% Duty Operation ................................................................ 12 Input and Output Capacitor, Recommended Specifications .. 3 Discharge Switch ........................................................................ 12 Absolute Maximum Ratings ............................................................ 4 Applications Information .............................................................. 13 Thermal Resistance ...................................................................... 4 ADIsimPower Design Tool ....................................................... 13 ESD Caution .................................................................................. 4 External Component Selection ................................................ 13 Pin Configuration and Function Descriptions ............................. 5 Thermal Considerations ............................................................ 14 Typical Performance Characteristics ............................................. 6 PCB Layout Guidelines.............................................................. 14 Theory of Operation ...................................................................... 11 Evaluation Board ............................................................................ 15 Control Scheme .......................................................................... 11 Evaluation Board Layout ........................................................... 15 PWM Mode ................................................................................. 11 Outline Dimensions ....................................................................... 16 Power Save Mode ........................................................................ 11 Ordering Guide .......................................................................... 17 Enable/Shutdown ....................................................................... 11 REVISION HISTORY 1/13Rev. B to Rev. C Change to Figure 18, Caption ........................................................ 8 Change to Figure 28, Caption ....................................................... 10 6/12Rev. A to Rev. B Change to Features Section ............................................................. 1 Added ADIsimPower Design Tool Section ................................. 13 Changes to Ordering Guide .......................................................... 17 4/11Rev. 0 to Rev. A Change to Features Section ............................................................. 1 Added Figure 32, Renumbered Figures Sequentially ................ 10 Changes to Ordering Guide .......................................................... 16 1/11Revision 0: Initial Version Rev. C Page 2 of 20