> How do I find MOSFETs (Vmos, whatever) with Vgs >= 30V ? (otherwise Vds
>800V, a few amps, a few ohms). I was unable to find anything on the
>
> Internet. Is there a way to do a parametric search across manufacturers ?
> I need small qty. so quoting price for 1000's is not good. In fact, why
> are thee rather rare ?

Google
                FET "800 V" "5 A"
says:

FQP5N80
800V, 5.8A, Rdson = 2.6 ohm
Vgss max = +/- 30v

    http://www.fairchildsemi.com/ds/FQ/FQP5N80.pdf

    Backward search into Farnell says

        394-4098  about $US2.50 in 1's

___________________

Google says:

2SK2765-01  similar specs

        http://www.fujielectric.de/SEMI/Datenblatt/MOSFET/2sk2765.pdf




______________


FETs are usually made to have as low a Vgs as possible consistent with
application and price. High Vgs is usually a relative disadvantage. The
upper level is set by gate oxide thickness. Unless you are replacing a FET
in an existing circuit where they use extremely high drive voltages a drive
voltage of 12v is usually adequate to fully enhance almost any FET  at full
rated current.

800v parts are more expensive to make and as many high voltage applications
revolve around voltage derived from rectifed mains 800v parts are less
sought after so less common so more expensive.  RS & Farnell catalogues are
often good starting points. Also parametric search on manufacturers web
sites. ON semi is often good for this.

Rdson also increases with voltage.

Farnell:

800v STP5NB80, 2r2, 5A, TO220
900v STP6NB90, 2r, 5A8, TO220
1000v STP5NB100, 2r7, 5A, TO220

These may have been discontinued

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.