Do you mean by loss the energy dissipation on the Drain-Source side of the MOSFET, during the switching? It will largely depend on how fast the MOSFET goes from the "open" to "closed" state. I would start by choosing first the Vgs_1 high enough to get the Vds under load as low as you need it for your "charge" part of the cycle, and then would go on optimizing the circuit on the Mosfet drive side to get Vgs from 0 to Vgs_1 and back as fast as possible. Then simulate and validate the energy dissipation.
International Rectifier has a good application note on driving mosfets.
Application Note AN-937 Gate Drive Characteristics and Requirements for HEXFET Power MOSFETs
I don't have the link but a search ought to do it.
When they give you the characteristic curves, that tells you what it takes to use it as a saturated switch - what you are doing . . .
The ten volts is probably turned on fully so there's no point in carrying the graph out further.
The only things to watch for is to get enough current to the gate fast enough to charge and discharge the 1500 pf of gate capacitance - or you'll be in the linear region and creating heat. They may have a very high gate impedance - but that pesky gate capacitance requires current to keep it from spending time in the linear region during the transitions - so the driver impedance has to be low
Keep transients on the gate (and drain) subdued or they might easily exceed the 30 volt maximum and cause a failure. That usually means short wire runs from driver to gate and/or gate resistor or snubbing network. If you rely on diodes for protection - they have to be fast switching diodes.
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Yup..it's the gate peak voltage for low drain source switching loss. I'm letting the mosfet do whatever it can do in the way of rapid current rise and fall times for reducing Pds switching loss.
Are you saying I should use the lowest gate voltage possible for sufficient drain current? That way there is less gate charging and discharging? A gate charged to say 6V can be discharged faster than say a gate charged to 20V.
I'm using a IXDD414 mosfet driver with a impressive speedy 14A peak current rating. Probably overkill but just using overrated parts for assurance. I'll check out the app note and take care with the PCB layout for the gate trace. Thanks. D from BC
Ooops..I just realized I forgot a word in my last post * * Rewrite: "I'm letting the mosfet *driver* do whatever it can do in the way of rapid current rise and fall times for reducing Pds switching loss." That probably caused some confusion...
Thanks for the info. Gonna juggle some parameters now. :) D from BC