IRF840 N,HEX instead of an IRF 710 N,MOS

[Ryssen]

Can I use an IRF840 N,HEX instead of an IRF 710 N,MOS
in a regulated 330Volts supply?
What´s the difference beetwen HEX and MOS?

[nine76chris]

Go to international rectifier's web site and check it out. I believe the 840 has a higher voltage rating and thats ok but the higher the voltage rating the higher the Rds(on) which would mean more power dissipation and lower current ratings. And that is all dependant on the die size. If they have similar Rds(on) and Id ratings then I'd use it, they all work the same.

[Ryssen]

Oki,thanks for the answer!

[Petter]

RdsON is not usually a problem and not usually a factor in power dissipation if you are building amplifiers where other factors such as gate charge and linearity of device is much more important.

Based on the numbering scheme (I have not looked at the datasheets), it would appear that the *10 version is a higher on-resistance, lower gate charge device which would typically be good for audio. Be sure to check the thermal resistances as well - you need to check all the way - from die to heatsink interface.

It really is a function of the application you are aiming for which determines what parameters to aim for when looking for substitute devices.

HEX is International Rectifiers brand presumably some sort of loose connection to their manufacturing process but mostly marketing.

You should be able to buy all IRF devices locally through www.elfa.se

Petter

[Ryssen]

It really is a function of the application you are aiming for which determines what parameters to aim for when looking for substitute devices.

I am going to use it as a voltageregulator for tube´s max 400V/100mA.

[nine76chris]

The mosfet were talking about are being used in a power supply, switching I presume....and doesn't power dissapation=I2 X R...aka Rds(on). And as far as gate charge goes(in a linear amplifier) would not pose a problem at audio frequencies(to 20Khz) unless many were inparallel, loading their drivers. In a switching power supply at high frequencies, transitions between off and on (and vice versa) need to be fast to avoid spending any time in the mosfets linear region(it's that I2 X R thing again) and thats where gate charge comes into play. In a linear amplifier there is now way around that.