Datasheet
ADP1877 Data Sheet
Rev. D | 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 .............................................. 18
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
4/12—Rev. C to Rev. D
Changes to Setting the Current Sense Gain Section .................. 18
Updated Outline Dimensions ....................................................... 31
4/10—Rev. B to Rev. C
Changes to Features and General Description ............................. 1
Changes to Quiescent Current Parameter and FB to TRK Offset
Voltage Parameter, Table 1 .............................................................. 3
Changes to Theory of Operation Section .................................... 13
Changes to Setting the Slope Compensation Section ................ 18
11/09—Rev. A to Rev. B
Changes to Product Title ................................................................. 1
Changes to Signal Path Section .................................................... 25
9/09—Rev. 0 to Rev. A
Changes to Features Section, General Description Section, and
Figure 2 ............................................................................................... 1
Changes to Output Characteristics, Feedback Accuracy Voltage
Parameter; Error Amplifier, Transconductance Parameter; and
Linear Regulator, VCCO Load Regulation and VIN to VCCO
Dropout Voltage Parameters, Table 1 ............................................. 3
Changes to Pin 4, Pin 16, and Pin 25 Descriptions, Table 3 ........ 8
Changes to Figure 5 and Figure 6 ................................................. 10
9/09—Revision 0: Initial Version