Datasheet ADP1851 (Analog Devices) - 2

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ADP1851 Data Sheet TABLE OF CONTENTS
Features .. 1 Enable/Disable Control ... 14 Applications ... 1 Thermal Overload Protection .. 14 General Description ... 1 Applications Information .. 15 Typical Operation Circuit .. 1 ADIsimPower Design Tool ... 15 Revision History ... 2 Setting the Output Voltage .. 15 Simplified Block Diagram ... 3 Soft Start .. 15 Specifications ... 4 Setting the Current Limit .. 15 Absolute Maximum Ratings .. 6 Accurate Current-Limit Sensing .. 15 ESD Caution .. 6 Input Capacitor Selection .. 15 Pin Configuration and Function Descriptions ... 7 VIN Pin Filter ... 16 Typical Performance Characteristics ... 9 Boost Capacitor Selection ... 16 Theory of Operation .. 11 Inductor Selection .. 16 Control Architecture .. 11 Output Capacitor Selection ... 16 Oscillator Frequency .. 11 MOSFET Selection ... 17 Synchronization .. 12 Loop Compensation—Voltage Mode .. 18 PWM and Pulse Skip Modes of Operation ... 12 Loop Compensation—Current Mode ... 19 Synchronous Rectifier and Dead Time ... 13 Switching Noise and Overshoot Reduction .. 20 Input Undervoltage Lockout ... 13 Voltage Tracking ... 21 Internal Linear Regulator .. 13 PCB Layout Guidelines .. 21 Overvoltage Protection .. 13 Typical Operating Circuits .. 22 Power Good ... 13 Outline Dimensions ... 23 Short-Circuit and Current-Limit Protection .. 14 Ordering Guide .. 23
REVISION HISTORY 4/2019—Rev. A to Rev. B
Changes to Figure 24 .. 15
2/2017—Rev. 0 to Rev. A
Updated Outline Dimensions ... 23 Change to Ordering Guide .. 23
8/2012—Revision 0: Initial Version
Rev. B | Page 2 of 24 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TYPICAL OPERATION CIRCUIT REVISION HISTORY SIMPLIFIED BLOCK DIAGRAM SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION CONTROL ARCHITECTURE OSCILLATOR FREQUENCY SYNCHRONIZATION PWM AND PULSE SKIP MODES OF OPERATION SYNCHRONOUS RECTIFIER AND DEAD TIME INPUT UNDERVOLTAGE LOCKOUT INTERNAL LINEAR REGULATOR OVERVOLTAGE PROTECTION POWER GOOD SHORT-CIRCUIT AND CURRENT-LIMIT PROTECTION ENABLE/DISABLE CONTROL THERMAL OVERLOAD PROTECTION APPLICATIONS INFORMATION ADIsimPower DESIGN TOOL SETTING THE OUTPUT VOLTAGE SOFT START SETTING THE CURRENT LIMIT ACCURATE CURRENT-LIMIT SENSING INPUT CAPACITOR SELECTION VIN PIN FILTER BOOST CAPACITOR SELECTION INDUCTOR SELECTION OUTPUT CAPACITOR SELECTION MOSFET SELECTION LOOP COMPENSATION—VOLTAGE MODE Type III Compensation LOOP COMPENSATION—CURRENT MODE Setting the Slope Compensation Setting the Current Sense Gain Type II Compensation SWITCHING NOISE AND OVERSHOOT REDUCTION VOLTAGE TRACKING Coincident Tracking Ratiometric Tracking PCB LAYOUT GUIDELINES TYPICAL OPERATING CIRCUITS OUTLINE DIMENSIONS ORDERING GUIDE