ADP1877

Rev. 0 | Page 2 of 32

TABLE OF CONTENTS

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

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

General

Description.......................................................................... 1

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

Specifications..................................................................................... 3

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

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

Simplified Block Diagram ............................................................... 7

Pin Configuration and Function Descriptions............................. 8

Typical Performance Characteristics ........................................... 10

Theory of Operation ...................................................................... 13

Control Architecture.................................................................. 13

Oscillator Frequency .................................................................. 13

Mode of Operation..................................................................... 14

Synchronization.......................................................................... 14

Soft Start ...................................................................................... 14

Synchronous Rectifier and Dead Time ................................... 15

Input Undervoltage Lockout..................................................... 15

Internal Linear Regulator .......................................................... 15

Overvoltage Protection.............................................................. 15

Power Good................................................................................. 15

Short Circuit and Current Limit Protection ........................... 16

Shutdown Control ...................................................................... 16

Thermal Overload Protection................................................... 16

Applications Information .............................................................. 17

Setting the Output Voltage ........................................................ 17

Soft Start ...................................................................................... 17

Setting the Current Limit .......................................................... 17

Accurate Current Limit Sensing............................................... 17

Setting the Slope Compensation .............................................. 18

Setting the Current Sense Gain ................................................ 18

Input Capacitor Selection.......................................................... 19

Input Filter................................................................................... 19

Boost Capacitor Selection ......................................................... 20

Inductor Selection ...................................................................... 20

Output Capacitor Selection....................................................... 20

MOSFET Selection..................................................................... 21

Loop Compensation .................................................................. 22

Switching Noise and Overshoot Reduction............................ 23

Voltage Tracking......................................................................... 23

Coincident Tracking .................................................................. 23

Ratiometric Tracking ................................................................. 24

PCB Layout Guideline ................................................................... 25

MOSFETs, Input Bulk Capacitor, and Bypass Capacitor ...... 25

High Current and Current Sense Paths................................... 25

Signal Paths ................................................................................. 25

PGND Plane................................................................................ 25

Feedback and Current Limit Sense Paths ............................... 25

Switch Node ................................................................................ 26

Gate Driver Paths ....................................................................... 26

Output Capacitors ...................................................................... 26

Typical Operating Circuits ............................................................ 27

Outline Dimensions ....................................................................... 31

Ordering Guide .......................................................................... 31

REVISION HISTORY

9/09—Revision 0: Initial Version