Data Sheet

LTC7892

analog.com

Rev. 0

2 of 50

TABLE OF CONTENTS

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

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

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

Typical Application....................................................................................................................................................................................1

Revision History .........................................................................................................................................................................................3

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

Absolute Maximum Ratings ......................................................................................................................................................................9

Pin Configurations and Function Descriptions......................................................................................................................................10

Typical Performance Characteristics .....................................................................................................................................................14

Functional Diagram .................................................................................................................................................................................19

Theory of Operation ................................................................................................................................................................................20

Main Control Loop...............................................................................................................................................................................20

Power and Bias Supplies (VBIAS, EXTVCC, DRVCC, INTVCC)......................................................................................................................20

High Side Bootstrap Capacitor...........................................................................................................................................................20

Dead Time Control (DTCA and DTCB Pins) ........................................................................................................................................21

Start-Up and Shutdown (RUN and SS Pins) ......................................................................................................................................21

Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) ........................21

Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) ...........................................22

Output Overvoltage Protection..........................................................................................................................................................23

Power Good .........................................................................................................................................................................................23

Applications Information ........................................................................................................................................................................24

Inductor Value Calculation .................................................................................................................................................................24

Inductor Core Selection......................................................................................................................................................................24

Current Sense Selection .....................................................................................................................................................................25

Low Value Resistor Current Sensing ..................................................................................................................................................25

Inductor DCR Current Sensing ...........................................................................................................................................................26

Setting the Operating Frequency.......................................................................................................................................................28

Selecting the Light-Load Operating Mode.........................................................................................................................................29

Dead Time Control (DTCA and DTCB Pins) ........................................................................................................................................30

DTCx Pin Tied to Ground (Adaptive Dead Time Control)..................................................................................................................31

DTCx Pin connected with a resistor to GND ......................................................................................................................................31

Power FET Selection ...........................................................................................................................................................................32

CIN and COUT Selection ..........................................................................................................................................................................33

Single Output 2-Phase Operation ......................................................................................................................................................34