36 V,1 A, Synchronous, Step-Down, DC-to-DC Regulator with External Clock Synchronization Data Sheet ADP2442 FEATURES TYPICAL CIRCUIT CONFIGURATION C2 Wide input voltage range from 4.5 V to 36 V Low minimum on time of 50 ns typical C1 Maximum load current of 1 A V OUT C BOOST High efficiency of up to 94% R TOP Adjustable output down to 0.6 V V IN FB VIN 1% output voltage accuracy R ADP2442 BOTTOM V OUT SW Adjustable switching frequency from 300 kHz to 1 MHz COMP C C OUT External synchronization from 300 kHz to 1 MHz R IN COMP PGND Pulse skip mode or forced fixed frequency mode EN C COMP Precision enable input pin (EN) Open-drain power good R FREQ Internal soft start Overcurrent-limit protection Figure 1. Shutdown current of less than 15 A The ADP2442 offers the flexibility of external clock UVLO and thermal shutdown synchronization. The switching frequency can be synchronized to 12-lead, 3 mm 3 mm LFCSP package an external clock, applied to the SYNC/MODE pin. The ADP2442 Supported by the ADIsimPower tool set can also be configured to operate in the forced fixed frequency Reference similar product ADP2441 with programmable soft mode for low EMI or power saving mode to reduce the switching start and tracking losses at light load. APPLICATIONS The ADP2442 uses hiccup mode to protect the IC from short Point of load applications circuits or from overcurrent conditions on the output. The internal Distributed power systems soft start limits inrush current during startup for a wide variety of Industrial control supplies load capacitances. Other key features include input undervoltage Standard rail conversion to 24 V/12 V/5 V/3.3 V lockout (UVLO), thermal shutdown (TSD), and precision enable GENERAL DESCRIPTION (EN), which can also be used as a logic level shutdown input. The ADP2442 is a constant frequency, current mode control, The ADP2442 is available in a 3 mm 3 mm, 12-lead LFCSP synchronous, step-down, dc-to-dc regulator that is capable of package and is rated for a junction temperature range from driving loads of up to 1 A with excellent line and load regulation 40C to +125C. characteristics. The ADP2442 operates with a wide input voltage 100 range from 4.5 V to 36 V, which makes it ideal for regulating 90 V = 12V OUT power from a wide variety of sources. In addition, the ADP2442 80 has very low minimum on time (50 ns) and is, therefore, suitable V = 5V OUT 70 for applications requiring a very high step-down ratio. 60 The output voltage can be adjusted from 0.6 V to 0.9 VIN. High 50 efficiency is obtained with integrated low resistance N-channel V = 3.3V OUT 40 MOSFETs for both high-side and low-side devices. 30 The switching frequency is adjustable from 300 kHz to 1 MHz with an external resistor. The ADP2442 also has an accurate power-good 20 V = 24V (PGOOD) open-drain output signal. IN 10 PWM = 300kHz 0 0.01 0.1 1 LOAD (A) Figure 2. Efficiency vs. Load Current, V = 24 V IN Rev. B Document Feedback 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 20122015 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. EFFICIENCY (%) PGOOD AGND FREQ VCC SYNC/ MODE BST 10667-001 10667-002ADP2442 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Thermal Shutdown .................................................................... 18 Applications ....................................................................................... 1 Applications Information .............................................................. 19 General Description ......................................................................... 1 ADIsimPower Design Tool ....................................................... 19 Typical Circuit Configuration ......................................................... 1 Selecting the Output Voltage .................................................... 19 Revision History ............................................................................... 2 Setting the Switching Frequency .............................................. 19 Specifications ..................................................................................... 3 External Component Selection ................................................ 20 Absolute Maximum Ratings ............................................................ 5 Boost Capacitor .......................................................................... 22 Thermal Resistance ...................................................................... 5 VCC Capacitor............................................................................ 22 ESD Caution .................................................................................. 5 Loop Compensation .................................................................. 22 Pin Configuration and Function Descriptions ............................. 6 Large Signal Analysis of the Loop Compensation ................. 22 Typical Performance Characteristics ............................................. 7 Design Example .............................................................................. 24 Efficiency in Forced Fixed Frequency Mode ............................ 7 Configuration and Components Selection ............................. 24 Efficiency in Pulse Skip Mode .................................................... 8 System Configuration ................................................................ 25 Internal Block Diagram ................................................................. 15 Typical Application Circuits ......................................................... 26 Theory of Operation ...................................................................... 16 Design Example .......................................................................... 26 Control Architecure ................................................................... 16 Other Typical Circuit Configurations ..................................... 27 Adjustable Frequency ................................................................. 17 Power Dissipation and Thermal Considerations ....................... 31 Power Good ................................................................................. 17 Power Dissipation....................................................................... 31 Mode of Operation ..................................................................... 17 Thermal Considerations ............................................................ 31 External Synchronization .......................................................... 17 Evaluation Board Thermal Performance ................................ 32 Soft Start ...................................................................................... 17 Circuit Board Layout Recommendations ................................... 33 Undervoltage Lockout ............................................................... 17 Outline Dimensions ....................................................................... 34 Precision Enable/Shutdown ...................................................... 17 Ordering Guide .......................................................................... 34 Current-Limit and Short-Circuit Protection .............................. 18 REVISION HISTORY 8/15Rev. A to Rev. B Changes to Figure 51 ...................................................................... 15 5/14Rev. 0 to Rev. A Change to Features Section ............................................................. 1 11/12Revision 0: Initial Version Rev. B Page 2 of 36