ADP2121

Rev. B | Page 2 of 20

TABLE OF CONTENTS

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

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

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

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

Typical Performance......................................................................... 1

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

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

Absolute Maximum Ratings............................................................ 4

Thermal Data ................................................................................ 4

Thermal Resistance ...................................................................... 4

ESD Caution.................................................................................. 4

Pin Configuration and Function Descriptions............................. 5

Typical Performance Characteristics ............................................. 6

Theory of Operation ...................................................................... 14

Overview ..................................................................................... 14

Mode Selection ........................................................................... 14

Enable/Shutdown ....................................................................... 15

Internal Control Features .......................................................... 15

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

Inductor Selection ...................................................................... 17

Input Capacitor Selection.......................................................... 17

Output Capacitor Selection....................................................... 17

PCB Layout Guidelines.................................................................. 19

Outline Dimensions....................................................................... 20

Ordering Guide .......................................................................... 20

REVISION HISTORY

1/11—Rev. A to Rev. B

Changes to Table 2 Summary.......................................................... 3

Changes to Undervoltage Lockout Threshold Parameter and

Output Voltage Accuracy Parameter in Table 2 ........................... 3

6/10—Rev. 0 to Rev. A

Changes to Features, General Description, Figure 1, and

Figure 2; Added Table 1; Renumbered Sequentially................ 1

Changes to Table 2............................................................................ 3

Changes to Table 3............................................................................ 4

Change to Typical Performance Characteristics Condition

Statement; Reorganized Typical Performance Characteristics

Section; Changes to Figure 4, Figure 6, Figure 7, and Figure 9;

Added Figure 5 and Figure 8; Renumbered Sequentially ....... 6

Changes to Figure 10 to Figure 12; Added Figure 13 to Figure 15... 7

Changes to Figure 16, Figure 17, Figure 19, and Figure 20..........8

Changes to Figure 22; Added Figure 23 and Figure 24 ................9

Added Figure 40, Figure 42, Figure 43, and Figure 45 .............. 12

Added Figure 46 and Figure 48; Changes to Figure 47 ............. 13

Changes to Figure 51 and the Overview Section ....................... 14

Changes to the Auto Mode (PFM and PWM Switching) Section,

Figure 53, the Mode Transition Section, and the Enable/

Shutdown Section....................................................................... 15

Changes to the Output Short-Circuit Protection Section and

Figure 55...................................................................................... 16

Changes to the Output Capacitor Selection Section ................. 17

Changes to Table 6, Table 7, and Table 8..................................... 18

Changes to Ordering Guide.......................................................... 20

4/09—Revision 0: Initial Version