RE: gEDA-user: mosfet design help

["Mike Hansen" <mehansen10@xxxxxxxxxxx>]

Most mosfets are driven with typically 10-12V for the gate drive.  I have 
never seen a mosfet with a 50V gate drive requirement.

If high side drive is a concern here you may want to look at bootstrap 
devices that are available to drive the high side mosfet.  It's unclear to 
me exactly what you are attempting here but if I read it right you basically 
have 10V to work with(+5 and -5 supplies).   If you work with a p channel 
device on the high side you should have no problems generating the gate 
voltages necessary to drive the mosfets without the need for a bootstrapping 
device.


> From: gene glick <carzrgr8@xxxxxxxxxxxxx>
> Reply-To: gEDA user mailing list <geda-user@xxxxxxxxxxxxxx>
> To: gEDA user mailing list <geda-user@xxxxxxxxxxxxxx>
> Subject: gEDA-user: mosfet design help
> Date: Sun, 03 Dec 2006 05:43:08 +0000
>
> I want to build a mosfet inverter that also translates voltages. Pretty 
> much standard mosfet inverter, nmos is lower transistor, pmos is upper 
> transistor.  The upper pmosfet Vsource is +5VDC, and mosfet Vsource is 
> -5VDC.  But, the gate voltage is +/- 50VDC.
>
> Although the gate voltage exceeds the turn-on threshold of the mosfet's - 
> but does it violate any max values for Vgs or Vgd?  At these levels, the 
> Vgs is going to around 55 volts.  The Vds is fine, and is easy to select a 
> transistor for these levels.
>
> It's not clear to me what the Vgs and Vgd maximums are, from reading 
> various mosfet data sheets. Any help?
>
> gene
>
>
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