ADP1851

Data Sheet

Rev. B | Page 2 of 24

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications....................................................................................... 1

General Description ......................................................................... 1

Typical Operation Circuit................................................................ 1

Revision History ............................................................................... 2

Simplified Block Diagram ............................................................... 3

Specifications..................................................................................... 4

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configuration and Function Descriptions............................. 7

Typical Performance Characteristics ............................................. 9

Theory of Operation ...................................................................... 11

Control Architecture.................................................................. 11

Oscillator Frequency .................................................................. 11

Synchronization.......................................................................... 12

PWM and Pulse Skip Modes of Operation............................. 12

Synchronous Rectifier and Dead Time ................................... 13

Input Undervoltage Lockout..................................................... 13

Internal Linear Regulator .......................................................... 13

Overvoltage Protection.............................................................. 13

Power Good................................................................................. 13

Short-Circuit and Current-Limit Protection .......................... 14

Enable/Disable Control ............................................................. 14

Thermal Overload Protection .................................................. 14

Applications Information .............................................................. 15

ADIsimPower Design Tool ....................................................... 15

Setting the Output Voltage........................................................ 15

Soft Start ...................................................................................... 15

Setting the Current Limit .......................................................... 15

Accurate Current-Limit Sensing .............................................. 15

Input Capacitor Selection.......................................................... 15

VIN Pin Filter ............................................................................. 16

Boost Capacitor Selection ......................................................... 16

Inductor Selection ...................................................................... 16

Output Capacitor Selection....................................................... 16

MOSFET Selection..................................................................... 17

Loop Compensation—Voltage Mode ...................................... 18

Loop Compensation—Current Mode ..................................... 19

Switching Noise and Overshoot Reduction............................ 20

Voltage Tracking......................................................................... 21

PCB Layout Guidelines.............................................................. 21

Typical Operating Circuits ............................................................ 22

Outline Dimensions ....................................................................... 23

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