What do you think of these lateral FETs?

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I used them to build an Elliott Sound Products P101 power amp and I am very happy with them. I am using two negative and two positive devices per channel on 70V rails. The amp has a considerable amount of power and is very neutral sounding, no coloration. The only down side is that they are no where near as a efficient as bipolar transistors.

The Exicons are basically clones of the old Hitachi 2SK1058 and 2SJ162 which were designed specifically for audio.

If you are interested in starting out with a high qualility, well designed, blank PCB check out Elliott Sound Products.
 
Hmm, interesting.

If the data sheets are correct and I'm interpreting them correctly, the input capacitances of the complementary ECX10xxxx devices are exactly the same, whereas the hitachi laterals have up to 50% difference. Seems these devices are a better match?
 
There's : Cgs - Cgd - Cds

Crss (r of reverse ) = Cgd

Ciss (i of in) = Cgd + Cgs.
Or,...Ciss =Crss + Cgs

Coss (o of out) = Cgd + Cds.
Or,...Coss = Crss + Cds.

For the input capacitance, only Crss and Ciss count.
None of the lateral MOSFETs, original Hitachi or afterlifes have equal input capacitance for N- and P-channels.
 
swordfishy you are not losing it. Exicon does specify the input capitance at 500pF for both the ECX10N20R and the EXC10P20R but that seems like a mistake to me. The specs seems normal for all the other lateral mosfets that they make. Send an email to Profusion plc and see if they reply. It wouldn't be the first time a data sheet was wrong. On the very first project that I built I had a data sheet from Fairchild Semiconductor that had the pinout for a MPSA42 reversed.

I am not real strong on theory but I believe this makes a difference. I built an ESP P101 using an earlier version of the Exicon mosfets and, per the instruction, a 220pF capacitor is soldered across the gate and source of the negative device to prevent oscillation. My amp does not oscillate.

Solder on,
George
 
None of the lateral MOSFETs, original Hitachi or afterlifes have equal input capacitance for N- and P-channels.

Right, but they did have almost the same thermal indifference
current, at about 100mA, while these ones are largely different,
being 150ma for a polarity and about 500mA for the complementary...

I checked the first device on the list above, since it s about
the same power and current capability as the Hitachi.....
 
George,

Thank you for taking the time to look at the datasheets and understand where I was coming from. As you noted, all of the capacitances, Ciss Coss, etc are listed as the same for both devices, which the discussions here have shown must be erroneous.

I may get in touch with you to ask you some questions about the ESP design if that is OK with you. Elliot's recommendation to use the gate capacitor is what made me start thinking about the capacitances in the first place.

I will email exicon and mention the error.

Jacco,

You are right - looking at the graphs shows there is a clear difference. Thank you for explaining.

Cheers,

greg.
 
Hi Greg,

Feel free to contact me about ESP products but keep in mind I am no expert. I wouldn't know a Reverse Transfer Capacitance if it bit me in the leg but I have successfully completed several projects including a high power P101. In fact the P101 was my first project ever. I learned from my mistakes. Attached is a link to some pictures of my P101.
ImageShack Album - 11 images

Solder on,
George
 
Plenty of folks who take numbers of the first few pages of a datasheet for granted.

Even if those numbers are correct, instead of typos in both the ECX10 and ECX08 sheets, they can often not be compared to similar devices due to differing measurement conditions.
Examples are JFET datasheets, transconductance numbers of two parts turn out far apart at identical conditions, while the printed nominal numbers suggest otherwise.
(real paper data in semiconductor books is much more elaborate/detailed than pdf datasheets, btw)
 
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