1
Abstract ............................................................................................. 5
2
Design Procedure ............................................................................ 5
2.1
Target Specifications .................................................................................................................... 5
2.2
Design of Power Stage ................................................................................................................. 6
2.2.1
System specifications ...................................................................................................................... 6
2.2.2
2.2.3
Voltage gain .................................................................................................................................... 7
2.2.4
Transformer turns ratio .................................................................................................................... 7
2.2.5
Effective load resistance ................................................................................................................. 7
2.2.6
Resonant network ........................................................................................................................... 7
2.2.7
Transformer design ......................................................................................................................... 9
2.2.8
SR MOSFET ................................................................................................................................. 10
2.3
2.3.1
Frequency setting: ......................................................................................................................... 10
2.3.2
2.3.3
Frequency setting for OCP: ........................................................................................................... 11
2.3.4
Dead time ...................................................................................................................................... 12
2.3.5
2.3.6
Load pin setting ............................................................................................................................. 13
2.3.7
Current sense ................................................................................................................................ 13
2.3.8
VINS pin setting ............................................................................................................................ 15
2.3.9
2.4
2.4.1
2.4.2
2.4.3
2.4.4
2.4.5
SR Protections .............................................................................................................................. 22
2.5
Design summary ......................................................................................................................... 22
3
Tips on PCB layout ........................................................................ 24
3.1
3.2
Star connection for IC ................................................................................................................. 25
Application Note
Table of Content
- Vres pin ................................................................................................. 20
_
on
delay
- Delay pin .............................................................................. 21
T
_
4
Page
2011-07-06