Quasi-resonant CoolSET design guide
ICE2QRxx65/80x
Design Guide
4
8 August 2011
Table of Contents
1
Introduction .......................................................................................................5
2
CoolSET description.........................................................................................5
2.1
Main features.......................................................................................................................5
2.2
Pin layout.............................................................................................................................5
2.3
Pin functions .......................................................................................................................6
2.3.1
ZC (Zero Crossing) ..........................................................................................................6
2.3.2
FB (Feedback) .................................................................................................................6
2.3.3
CS (Current Sensing) ......................................................................................................6
2.3.4
Drain ................................................................................................................................6
2.3.5
VCC (Power supply) ........................................................................................................6
2.3.6
GND (Ground) .................................................................................................................6
3
Overview of quasi-resonant flyback converter ..............................................6
4
Functional description and component design .............................................8
4.1
VCC Pre-Charging and Typical VCC Voltage During Start-up .......................................8
4.1.1
VCC Capacitor.................................................................................................................9
4.2
Soft-Start..............................................................................................................................9
4.3
Normal Operation..............................................................................................................10
4.3.1
Switch-on Determination ...............................................................................................10
4.3.2
Switch-off Determination ...............................................................................................11
4.4
Active Burst Mode Operation ..........................................................................................11
4.4.1
Entering Active Burst Mode Operation ..........................................................................11
4.4.2
During Burst Mode Operation........................................................................................12
4.4.3
Leaving Active Burst Mode............................................................................................13
4.5
Current sense....................................................................................................................13
4.6
Feedback ...........................................................................................................................13
4.7
Zero crossing ....................................................................................................................13
4.8
Protections ........................................................................................................................15
4.9
Others ................................................................................................................................15
5
Typical application circuit ..............................................................................15
6
Input Power Curves for Quasi Coolset 650V/800V.......................................16
7
PCB Layout Recommendation.......................................................................22
8
Product Portfolio Quasi Resonant CoolSET
®
...............................................22
9
Design Equations............................................................................................23
10
References ......................................................................................................24
