Hi buddy
Hi ZOX ,
Being a N-channel mosfet amp manufacturer, I think now its my turn to say something!.
yes its a smps mosfet, but you can very well use this in Quasi-complementary amp. You have to design a good driver stage to drive this mosfet. the driver idle current must be at least 40-60mA in order to drive this huge gate capacitance along with good damping factor.
You can draw upto 300WRMS @ 4 ohms just from a single pair very easily.
regards,
Kanwar
Hi ZOX ,
Being a N-channel mosfet amp manufacturer, I think now its my turn to say something!.
yes its a smps mosfet, but you can very well use this in Quasi-complementary amp. You have to design a good driver stage to drive this mosfet. the driver idle current must be at least 40-60mA in order to drive this huge gate capacitance along with good damping factor.
You can draw upto 300WRMS @ 4 ohms just from a single pair very easily.
regards,
Kanwar
I think you posted in a similar fashion to this a couple of days ago with another MOSFET. You would be better providing a link to the PDF datasheet as it is not enough to know just the voltage and current rating of the device. The wattage can be ignored for practical purposes in linear (class-b amp) use.
As I said last time, we need to see the safe operating area (SOA) graph. The input capacitance (Ciss) and gate charge (Qg) are also important parameters.
As I said last time, we need to see the safe operating area (SOA) graph. The input capacitance (Ciss) and gate charge (Qg) are also important parameters.
Data sheet and driver question
Here is link to Data Sheet:
http://www.irf.com/product-info/datasheets/data/irfp90n20d.pdf
What driver stage could be used to drive this "monster" MOSFET.
Any schematics?
Thanks
Here is link to Data Sheet:
http://www.irf.com/product-info/datasheets/data/irfp90n20d.pdf
What driver stage could be used to drive this "monster" MOSFET.
Any schematics?
Thanks
Re: Data sheet and driver question
Hi ZOX,
You can very well use "INDIVIDUAL PUSH_PULL DRIVERS" for upper rail and lower rail mosfets to achieve excellent sink-source properties.
using conventional driver schems is not worth, as they perform very poor in terms of turn-off time domain of mosfets.
regards,
kanwar
zox2003 said:
Hi ZOX,
You can very well use "INDIVIDUAL PUSH_PULL DRIVERS" for upper rail and lower rail mosfets to achieve excellent sink-source properties.
using conventional driver schems is not worth, as they perform very poor in terms of turn-off time domain of mosfets.
regards,
kanwar
very impressive curves there Kanwar 
I built a PA amp about 5 years ago running 4 x IXFH26N50 per rail.
www.ixys.com/91525.pdf
I used them because I got them for practically nothing.
Now this amp is OK for PA applications but the same cct and layout with the less powerful IRFP450 gave much better distortion figures.
As Workhorse has identified I had to also use more biasing current through my driver stage to get good control of the FETS. This meant that my driver transistors got too hot so I had to modify this stage as well. I'll try to find this cct and post it.
So IMHO unless you have these FETS in your parts box already go for more lower power FETS spread across a larger heatsink area. This will help resolve the issues identified by Stuart Easson, provide for less distortion and be less expensive than the "monster" solution.
Consider also that these FETS only have a 200 volt rating. This means that your maximum rail voltage must always remain at under 100 volts. I would only run rails at 90v (idle) to give a 10 volt safety margin. So to get around 300 watts RMS into 8 ohms your power supply must have a regulation of better than 10% from idle to full power and this means a very big power supply.
PS. I got even lower distortion using multiple IRF840's.
Good luck & cheers
www.ixys.com/91525.pdf
I used them because I got them for practically nothing.
Now this amp is OK for PA applications but the same cct and layout with the less powerful IRFP450 gave much better distortion figures.
As Workhorse has identified I had to also use more biasing current through my driver stage to get good control of the FETS. This meant that my driver transistors got too hot so I had to modify this stage as well. I'll try to find this cct and post it.
So IMHO unless you have these FETS in your parts box already go for more lower power FETS spread across a larger heatsink area. This will help resolve the issues identified by Stuart Easson, provide for less distortion and be less expensive than the "monster" solution.
Consider also that these FETS only have a 200 volt rating. This means that your maximum rail voltage must always remain at under 100 volts. I would only run rails at 90v (idle) to give a 10 volt safety margin. So to get around 300 watts RMS into 8 ohms your power supply must have a regulation of better than 10% from idle to full power and this means a very big power supply.
PS. I got even lower distortion using multiple IRF840's.
Good luck & cheers
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.