Hi Dwayne,

Ah, I see, that makes sense now,

Thanks,

Sean

At 04:44 PM 2/20/02 -0700, you wrote:
>At 06:22 PM 2/20/02 -0500, Sean H. Breheny wrote:
>>I haven't followed this from the beginning, so perhaps I am missing
>>something, but you have to remember that you won't be able to turn the
>>MOSFET off if the drain is more negative (or positive for PMOSFET) than the
>>body (usually connected to the source). In other words, it is true that it
>>conducts in both directions when fully on, but it will still conduct in one
>>direction when off. This is due to the inherent diode (body diode) created
>>by the PN junction between drain and body (substrate), and the fact that
>>the source is usually connected to the body.
>
>What you are missing is that there are 2 series-connected MOSFETs wired in
>series with the load such that the Source leads are tied together, as are
>the gate leads.  The switch terminals are the 2 Drain leads.  1 FET handles
>1 half-cycle, the other FET handles the remaining half-cycle.
>
>So, yes, one FET does not turn off on a given half-cycle.  But the other
>one does.
>
>dwayne
>
>
>Dwayne Reid   <dwayner@planet.eon.net>
>Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
>(780) 489-3199 voice          (780) 487-6397 fax
>
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