AN-1059 Datasheet, PDF (1/11 Pages) International Rectifier – Application Note

Application Note AN-1059
DirectFET^® Technology
Thermal Model and Rating Calculator
Table of Contents
Page
Introduction............................................................ 2
Equivalent circuits ................................................. 3
Thermal resistance values ............................... 3
Analysis ............................................................ 3
Rating Calculator ................................................... 5
Notes on use .................................................... 5
Rating Calculator inputs ................................... 5
Rating Calculator outputs................................. 5
Types of cooling ............................................... 6
Validation of results ............................................... 6
Model................................................................ 6
Values .............................................................. 7
Thermal resistance values .................................... 8
With equipment chassis or case cooling .......... 8
With no additional DirectFET can cooling ........ 8
Example of use of Rating Calculator................ 9
Summary ............................................................... 9
Appendix A .......................................................... 10
Equation 1 ...................................................... 10
Equation 2a .................................................... 10
Equation 2b .................................................... 10
Appendix B .......................................................... 10
Appendix C .......................................................... 11
Appendix D .......................................................... 11
DirectFET’s thermal properties are fundamentally different from industry-standard, encapsulated power
semiconductors. Its construction encourages heat to disperse from the die in opposite directions,
cooling through both the substrate pad connections (source and gate) and the metal can on top of the
device. The can-to-ambient thermal interface can be maximized by fitting a heat sink.
DirectFET^® Technology
www.irf.com
AN-1059
Version 3, September 2010
Thermal Model and Rating Calculator
Page 1 of 11