ADP1879(RevA) Просмотр технического описания (PDF) - Analog Devices

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ADP1879
(Rev.:RevA)

Synchronous Buck Controller with Constant On Time and Valley Current Mode

Analog Devices 

ADP1878/ADP1879

TABLE OF CONTENTS

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

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

Typical Applications Circuit............................................................ 1

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

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

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

Absolute Maximum Ratings ....................................................... 5

Thermal Resistance ...................................................................... 5

ESD Caution.................................................................................. 5

Pin Configuration and Function Descriptions............................. 6

Typical Performance Characteristics ............................................. 7

Theory of Operation ...................................................................... 17

Block Diagram ............................................................................ 17

Startup.......................................................................................... 18

Soft Start ...................................................................................... 18

Precision Enable Circuitry ........................................................ 18

Undervoltage Lockout ............................................................... 18

On-Board Low Dropout (LDO) Regulator............................. 18

Thermal Shutdown..................................................................... 19

Programming Resistor (RES) Detect Circuit.......................... 19

Valley Current-Limit Setting .................................................... 19

Hiccup Mode During Short Circuit......................................... 21

Synchronous Rectifier................................................................ 21

ADP1879 Power Saving Mode (PSM)...................................... 21

Timer Operation......................................................................... 22

REVISION HISTORY

6/12—Rev. 0 to Rev. A

Changes to Table 1.............................................................................3

7/11—Revision 0: Initial Version

Data Sheet

Pseudo Fixed Frequency............................................................ 22

Power-Good Monitoring........................................................... 23

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

Feedback Resistor Divider ........................................................ 24

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

Output Ripple Voltage (ΔVRR) .................................................. 24

Output Capacitor Selection....................................................... 24

Compensation Network ............................................................ 25

Efficiency Consideration........................................................... 26

Input Capacitor Selection.......................................................... 27

Thermal Considerations............................................................ 27

Design Example .......................................................................... 29

External Component Recommendations.................................... 31

Layout Considerations ................................................................... 33

IC Section (Left Side of Evaluation Board)............................. 35

Power Section ............................................................................. 35

Differential Sensing.................................................................... 36

Typical Application Circuits ......................................................... 37

12 A, 300 kHz High Current Application Circuit.................. 37

5.5 V Input, 600 kHz Current Application Circuit ................ 37

300 kHz High Current Application Circuit ............................ 38

Packaging and Ordering Information ......................................... 39

Outline Dimensions................................................................... 39

Ordering Guide .......................................................................... 40

Rev. A | Page 2 of 40

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