Synchronous Current-Mode with Constant On-Time, PWM Buck Controller ADP1882/ADP1883 FEATURES TYPICAL APPLICATIONS CIRCUIT V = 2.75V TO 20V IN Power input voltage as low as 2.75 V to 20 V Bias supply voltage range: 2.75 V to 5.5 V VIN Minimum output voltage: 0.8 V C C ADP1882/ C C IN C2 0.8 V reference voltage with 1.0% accuracy R ADP1883 C R TOP COMP/EN BST Supports all N-channel MOSFET power stages V OUT C BST Q1 L V Available in 300 kHz, 600 kHz, and 1.0 MHz options FB DRVH OUT R BOT No current-sense resistor required GND SW C OUT Q2 C Power saving mode (PSM) for light loads (ADP1883 only) VDD2 VDD DRVL Resistor-programmable current-sense gain PGND R RES LOAD V = 2.75V TO 5.5V DD Thermal overload protection C VDD Short-circuit protection Figure 1. Precision enable input Integrated bootstrap diode for high-side drive 140 A shutdown supply current 100 Starts into a precharged load 95 90 Small, 10-lead MSOP package 85 V = 5.5V, V = 13.0V DD IN 80 APPLICATIONS V = 5.5V, V = 16.5V DD IN 75 Telecom and networking systems V = 5.5V, V = 5.5V (PSM) DD IN 70 V = 5.5V, V = 5.5V DD IN Mid to high end servers 65 V = 3.6V, V = 5.5V DD IN 60 Set-top boxes 55 DSP core power supplies 50 T = 25C A V = 1.8V OUT 45 f = 300kHz SW 40 WURTH INDUCTOR: 35 744325120, L = 1.2H, DCR = 1.8m INFINEON MOSFETs: 30 BSC042N03MS G (UPPER/LOWER) 25 100 1k 10k 100k LOAD CURRENT (mA) Figure 2. ADP1882/ADP1883 Efficiency vs. Load Current (V = 1.8 V, 300 kHz) OUT GENERAL DESCRIPTION The ADP1882/ADP1883 are versatile current-mode, synchronous Available in three frequency options (300 kHz, 600 kHz, and step-down controllers that provide superior transient response, 1.0 MHz, plus the PSM option), the ADP1882/ADP1883 are optimal stability, and current-limit protection by using a constant well suited for a wide range of applications. These ICs not only on-time, pseudo-fixed frequency with a programmable current- operate from a 2.75 V to 5.5 V bias supply, but they also can limit, current-control scheme. In addition, these devices offer accept a power input as high as 20 V. optimum performance at low duty cycles by using valley current- In addition, an internally fixed soft start period is included to limit mode control architecture. This allows the ADP1882/ADP1883 input in-rush current from the input supply during startup and to drive all N-channel power stages to regulate output voltages to provide reverse current protection during soft start for a pre- as low as 0.8 V. charged output. The low-side current-sense, current-gain scheme The ADP1883 is the power saving mode (PSM) version of the and integration of a boost diode, along with the PSM/forced device and is capable of pulse skipping to maintain output pulse-width modulation (PWM) option, reduce the external regulation while achieving improved system efficiency at light part count and improve efficiency. loads (see the Power Saving Mode (PSM) Version (ADP1883) The ADP1882/ADP1883 operate over the 40C to +125C section for more information). junction temperature range and are available in a 10-lead MSOP. 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. EFFICIENCY (%) 08901-002 08901-001ADP1882/ADP1883 TABLE OF CONTENTS Features .............................................................................................. 1 Timer Operation ........................................................................ 22 Applications ....................................................................................... 1 Pseudo-Fixed Frequency ........................................................... 23 Typical Applications Circuit ............................................................ 1 Applications Information .............................................................. 24 General Description ......................................................................... 1 Feedback Resistor Divider ........................................................ 24 Revision History ............................................................................... 2 Inductor Selection ...................................................................... 24 Specif icat ions ..................................................................................... 3 Output Ripple Voltage (V ) .................................................. 24 RR Absolute Maximum Ratings ............................................................ 5 Output Capacitor Selection ....................................................... 24 Thermal Resistance ...................................................................... 5 Compensation Network ............................................................ 25 Boundary Condition .................................................................... 5 Efficiency Considerations ......................................................... 26 ESD Caution .................................................................................. 5 Input Capacitor Selection .......................................................... 27 Pin Configuration and Function Descriptions ............................. 6 Thermal Considerations ............................................................ 28 Typical Performance Characteristics ............................................. 7 Design Example .......................................................................... 28 ADP1882/ADP1883 Block Diagram ............................................ 18 External Component Recommendations .................................... 31 Theory of Operation ...................................................................... 19 Layout Considerations ................................................................... 33 Startup .......................................................................................... 19 IC Section (Left Side of Evaluation Board) ............................. 36 Soft Start ...................................................................................... 19 Power Section ............................................................................. 36 Precision Enable Circuitry ........................................................ 19 Differential Sensing .................................................................... 36 Undervoltage Lockout ............................................................... 19 Typical Applications Circuits ........................................................ 37 Thermal Shutdown ..................................................................... 19 Dual-Input, 300 kHz High Current Applications Circuit ..... 37 Programming Resistor (RES) Detect Circuit .......................... 20 Single-Input, 600 kHz Applications Circuit ........................... 37 Valley Current-Limit Setting .................................................... 20 Dual-Input, 300 kHz High Current Applications Circuit ..... 38 Hiccup Mode During Short Circuit ......................................... 21 Outline Dimensions ....................................................................... 39 Synchronous Rectifier ................................................................ 22 Ordering Guide .......................................................................... 39 Power Saving Mode (PSM) Version (ADP1883) .................... 22 REVISION HISTORY 4/10Revision 0: Initial Version Rev. 0 Page 2 of 40