In my search for more information on these interesting devices, I happened to run across this Application Note from Cree called "Application Considerations for Silicon Carbide MOSFETs". I thought readers of this thread might find it informative also.I am struck by the possibilities for the CREE C2M1000170D
A quote from the note:
"Consider the output characteristics of a typical Cree CMF20120D and the Si TFS IGBT shown in Figure1. For the CMF20120D, the transition from triode (ohmic) to saturation (constant current) regions is not as clearly defined as it is for the Si TFS IGBT. This is a result of the modest transconductance of the device. The modest amount of transconductance causes the transition from triode to saturation to be spread over a wider range of drain current. The result is that the CMF20120D behaves more like a voltage controlled resistance than a voltage controlled current source."
They also talk about the assymmetric gate drive characteristics of the devices.
Thanks Papa for pointing us in this direction. I'm still trying to decide which of the Cree devices to play with.
Papa,
I've been looking at the data sheets for the C2M100070 and others in the series and trying to discover what characteristics of that device caught your interest. I see that the Ciss looks really flat across the Vds range. I also saw that the transconductance is only 0.8 or so. Is this a bad thing? I can see how the small capacitances and insensitivity to change in VDS would decrease distortion. Am I anywhere close? The price is pretty good too!
Thanks for being here.....and for the knowledge you share.
I've been looking at the data sheets for the C2M100070 and others in the series and trying to discover what characteristics of that device caught your interest. I see that the Ciss looks really flat across the Vds range. I also saw that the transconductance is only 0.8 or so. Is this a bad thing? I can see how the small capacitances and insensitivity to change in VDS would decrease distortion. Am I anywhere close? The price is pretty good too!
Thanks for being here.....and for the knowledge you share.
Aspringv
Thank you for your excellent work testing these devices. I appreciate very much your kind offer. It looks from your matching data that the Vgs spread among your lot is not too bad. There are some good matches in there. I hope you get your amp working soon so we can learn how they sound!
Thank you for your excellent work testing these devices. I appreciate very much your kind offer. It looks from your matching data that the Vgs spread among your lot is not too bad. There are some good matches in there. I hope you get your amp working soon so we can learn how they sound!
I bought a few tubes of C2M1000170D, but haven't cleared the
decks enough to play with them.
Holy cow. Ciss is a flat line from below 10V to 200V Vds
Yup...
Transconductance is kind of low compared to IRFP240. But the low Ciss invites paralleling a bunch of these to make up for it. The curves that Aspringv posted for one of his devices look like they have a smooth square law characteristic. I bet Papa has something cool in mind for these.....
That's what you said already.Sorry, I meant C2M1000170D.
Now I don't know if you're just trying to stir us up or you forgot to put your glasses on.
Or no need for jfet buffering at input for the ultimate Zen One Hand Clapping, Send SET Tube Amps To The Junk Pile Amp.
Sorry, I meant C2M1000170D.
It was me that put the wrong part number......sorry for the confusion!
I bought a few tubes of C2M1000170D, but haven't cleared the
decks enough to play with them.
I purchased 10.
I purchased 10.
I placed an order for a tube of these and four of the higher transconductance lower Vds cousins to compare in a PLH type circuit I'm playing with. I am anxious to put them on my curve tracer to see what they look like in the lower current ranges that are hard to see on the data sheet curves. I'm also going to see how they sound in my ACA just for fun.
Hi 2 PicoDumbs
I try to buy from places like Digikey and Mouser and always look at the standard pack size. In the case of the Crees the standard pack was 30 so that is the quantity I ordered assuming they probably would send an unbroken full tube. I believe that the tubes are filled on the production line with devices from the same batch. But I don't think that is guaranteed - only probable. The Vishay devices like IRFP240 are packed in tubes of 25.
I think if you order half tube quantity for instance they cut the tube physically in half so you still have a good chance of getting similar devices. If you order 2 or 3 you might get the leftovers from the bottom of the bin.