Datasheet

ADP1872/ADP1873 Data Sheet
Rev. B | Page 2 of 40
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
Boundary Condition .................................................................... 5
ESD Caution .................................................................................. 5
Pin Configuration and Function Descriptions ............................. 6
Typical Performance Characteristics ............................................. 7
ADP1872/ADP1873 Block Digram .............................................. 17
Theory of Operation ...................................................................... 18
Startup .......................................................................................... 18
Soft Start ...................................................................................... 18
Precision Enable Circuitry ........................................................ 18
Undervoltage Lockout ............................................................... 18
Thermal Shutdown ..................................................................... 18
Programming Resistor (RES) Detect Circuit .......................... 19
Valley Current-Limit Setting .................................................... 19
Hiccup Mode During Short Circuit ......................................... 20
Synchronous Rectifier ................................................................ 21
Power Saving Mode (PSM) Version (ADP1873) .................... 21
Timer Operation ........................................................................ 21
Pseudo-Fixed Frequency ........................................................... 22
Applications Information .............................................................. 23
Feedback Resistor Divider ........................................................ 23
Inductor Selection ...................................................................... 23
Output Ripple Voltage (V
RR
) .................................................. 23
Output Capacitor Selection ....................................................... 23
Compensation Network ............................................................ 24
Efficiency Consideration ........................................................... 25
Input Capacitor Selection .......................................................... 26
Thermal Considerations ............................................................ 27
Design Example .......................................................................... 27
External Component Recommendations .................................... 30
Layout Considerations ................................................................... 32
IC Section (Left Side of Evaluation Board) ............................. 37
Power Section ............................................................................. 37
Differential Sensing .................................................................... 37
Typical Application Circuits ......................................................... 38
Dual-Input, 300 kHz High Current Application Circuit ...... 38
Single-Input, 600 kHz Application Circuit ............................. 38
Dual-Input, 300 kHz High Current Application Circuit ...... 39
Outline Dimensions ....................................................................... 40
Ordering Guide .......................................................................... 40
REVISION HISTORY
7/12—Rev. A to Rev. B
Changed R
ON
= 15 m/100 kΩ Valley Current Level Value from
7.5 to 3.87; Table 6 .......................................................................... 20
Changes to Ordering Guide .......................................................... 40
3/10—Rev. 0 to Rev. A
Changes to Figure 1 .......................................................................... 1
Changes to Table 1 ............................................................................ 3
Changes to Table 2 ............................................................................ 5
Changes to Figure 59 Caption and Figure 60 Caption .............. 16
Changes to Figure 64 ...................................................................... 17
Changes to Timer Operation Section .......................................... 22
Changes to Table 7 .......................................................................... 23
Changes to Inductor Section ......................................................... 28
Changes to Table 9 .......................................................................... 31
Changes to Figure 82 ...................................................................... 32
Changes to Figure 83 ...................................................................... 33
Changes to Figure 84 ...................................................................... 34
Changes to Figure 85 ...................................................................... 35
Changes to Figure 86 ...................................................................... 36
Changes to Differential Sensing Section and Figure 88 ............ 37
Changes to Figure 89 and Figure 90............................................. 38
Changes to Figure 91 ...................................................................... 39
Updated Outline Dimensions ....................................................... 40
10/09—Revision 0: Initial Version