I've noticed my mosfet psu is quietly oscillating and I've put a ferrite bead in both gate and drain legs. This has "shut it up"and now runs much cooler. Since mos oscillates well into UHF, I chose a material with a fairly low permeability i.e mu=700 philips 4A11 pink . Is this the correct approach and /or what is best ferrite material grade to use. Or broadband ? Anyone got any experience ?
richj
richj
Usually a ferrite bead on the gate should be sufficient. The mu and the losses in the material need to be just high enough so that the oscillation stops with a good margin.
Alternatively, you might beef up the gate driver and/or reduce the gate drive resistor, or move it closer to the gate.
Or, chose a older (slower) MOSFET - the new superjunction devices (think Fairchild SuperFET or Infineon CoolMOS) are getting faster and faster....
just my two cents...
Alternatively, you might beef up the gate driver and/or reduce the gate drive resistor, or move it closer to the gate.
Or, chose a older (slower) MOSFET - the new superjunction devices (think Fairchild SuperFET or Infineon CoolMOS) are getting faster and faster....
just my two cents...
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