Castle Creations Mamba Monster maxx ready for release

[Pdelcast]

Originally Posted by lutach

The 34A I mentioned is from NXP and I know Renessas have some as well with the same package. NXP said the MOSFET has an SO-8 foot print, but it acts as a DPAK. There is only one controller that I know of that is using these type of MOSFET (Not the 100V one though) and pictures can be found here:http://www.rc-monster.com/forum/show...&postcount=126. I was looking through the BSC079N10 datasheet and they say Tc 25C 100A and Tc 100C 64A, but the Ta at 25C is only 13.4A.

That's an LFPAK mosfet. Not as good as a SO-8 leadless (like the BSC079/BSC118/NTMFS4833) for dissipation. DPAK, SO-8, SO-8FL, LFPAK, it doesn't really matter. It's all about how much you can dissipate, and how much the FET can take internally. You see, the FET people have been "juicing" their ratings for years, so always take the ratings with a grain of salt. The NTMFS4833 we are using on the MMM is rated at 191A per FET -- can it really take that kind of current? No way, not even close!

About .3-.4 watts per FET is all you can hope to dissipate in a high density ESC type application (a little more with a good heat sink and fan, but not much more.) Anyone who tells you different is either wrong or lying.

The math really counts -- you can't fool physics.

Now, there are companies (like certain of our competitors) who like to just add up the FET ratings and call that the rating of their controllers. However, it is again total BS, as no FET can take that kind of power for more than a second or so. If we did that for the MMM, the rating of the MMM would be 1150 amps. Can the MMM take 1150A? No, it can't. Can our competitor's speed controls handle 700A? No, they can't, even if they are rated to do so.

And then some other competitors take a 20 second rating, and call that "continuous" --- Better, but still misleading in my opinion.

So we don't really want to get involved in creating total BS ratings for our controllers. And if we publish truly honest ratings, we will look anemic next to our competitors who are publishing BS ratings.

So what do we do? We create controllers that will handle pretty much anything you want to throw at them -- they are so over-built that there isn't any problems with power handling.

But I won't BS you and tell you the MMM will handle 1150A continuous like some of our competitors might... because the MMM won't handle 1150A continuous. Our Emaxx draws about 100A average, and about 800A during acceleration (for about a second or so), and the MMM handles it fine. (better than the motor in fact.) And it will take full throttle/ full brake / full throttle/ full brake continuously for as long as you want to do it on a system that will go 70mph on either an Emaxx or an 1/8 scale buggy, outputting about 2250 watts average and almost 10,000 watts peak.

So this is my dilemma.


So should I:

1. Give a real-world continuous and burst current rating that will make the MMM look anemic against competitors controllers when in fact the MMM will handle much more current than the competition?

or

2. Give a BS rating on the same scale as the competition which will allow customers to comparison shop on a level field, but are really totally BS numbers?

or

3. Just don't rate a continuous and peak rating because option 1 misleads some consumers and option 2 misleads other consumers?


Thanks for listening to me rant!!!


Patrick del Castillo
President
Castle Creations