Joe,

Going through these, thanks.  So far, yes I've calculated the off time=20
will be significantly longer than the on time, so I'm looking into=20
MOSFET drivers now.  I found a TC1411NCPA in a Microchip sample pack I=20
got several years ago, and thinking it would be good for an experiment.

Cheers,
-Neil.


On 10/8/2015 7:23 PM, IVP wrote:
>> The input to the MOSFET is driven by a PNP transistor with a 1k
>> pull-down resistor -- should I change that to a push-pull setup?
> Hi Neil,
>
> An NPN will ground [discharge the internal capacitances) faster
>  =20
> Power MOSFET Basics: Understanding Gate Charge
> and Using it to Assess Switching Performance
>
> http://www.vishay.com/docs/73217/73217.pdf
>
> Power MOSFET Basics
>
> http://www.irf.com/technical-info/appnotes/mosfet.pdf
>
> The advantage of using [the] gate charge [figure] is that the designer
> can easily calculate the amount of current required from the drive
> circuit to switch the device on in a desired length of time because
> Q =3D CV and I =3D C dv/dt, the Q =3D Time x current. For example, a
> device with a gate charge of 20nC can be turned on in 20usec if 1ma
> is supplied to the gate or it can turn on in 20nsec if the gate current i=
s
> increased to 1A. These simple calculations would not have been
> possible with [an] input capacitance value
>
> Joe
>
>
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--=20
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