DirectFET® MOSFET High Frequency Operation
Package Impedance vs. Frequency |
|
VRM Current Demands
- VRM designs operating frequency increasing to over 1MHz
- How do power electronic packages respond at 1MHz+?
|
VRM Power Dissipation
- Increasing peak current demands
- Area of PCB occupied by VRM decreasing
- Less area to dissipate the heat
- 30% of RDS(on) of best SO-8 is due to package
|
|
DirectFET MOSFET Package Benefits |
| Frequency effect over package impedance: Skin Effect |
Skin effect & skin depth
At high frequencies current is confined to the perimeter of solid conductors. This phenomenon is often referred to as the skin effect.
Skin depth  |
|
Theoretical modeling results under AC conditions
Developed MathCAD model using Maxwell’s equations. For a rectangular bar structure Rac/Rdc is a function of width over skin depth.
|
Apply the scale factor Rac/Rdc to each element in model at different values of frequency to predict R versus frequency behaviour…
|
