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LBRC
2007.10.28, 03:51 AM
Mentioned these in a MA-010 FET thread but decided they rate their own thread after spending a day playing with them.

On paper they’re very nice with a -7.3 amp continuous drain current for the P-channel and a total P+N on-state resistance of 54.5mΩ at 4.5V, for comparison the Vishay 4562 lists a -6.2 amp continuous drain current and a total P+N on-state resistance of 58mΩ at 4.5V.

Data Sheet Link: http://www.fairchildsemi.com/ds/FD/FDS8858CZ.pdf

Max rated continuous drain current at 25° C:
N-channel 8.6 amps
P-channel -7.3 amps

On-State Resistance:
N-Channel
• Max rDS(on) = 20mΩ at VGS = 4.5V, ID = 7.3A
P-Channel
• Max rDS(on) = 34.5mΩ at VGS = -4.5V, ID = -5.6A

Of course what the manufacturer lists on the data sheet and how they actually hold up in a Mini-Z is not always the same thing but so far for me they seem to be living up to the specks. First I put a 1x1 set in an old MR-01 and after tentatively playing around with different motors I got brave enough to pop in an Atomic T2 with a 6 then eventually 7 tooth pinion to run some wall bashing 50 lap sets on a 2xWide-L RCP track. Ran out of courage at the 7 tooth pinion though, even with a listed 7.3 amps I thought anything more would be asking for a miracle, besides a T2 in a MR-01 on a small track is bit more than I can handle. The question is how long will they last as a 1x1 with a motor as hot as the T2? My guess is that even though it has now gone through 4 NiMH battery sets and nearly 400 laps it’s just plain lucky to be alive.

After the MR-01 I put a 2x2 in a MA-010 with one of the blue MZWS BB practice motors (I believe it’s a 47 turn); noticeable power increase over the 3010’s with the same motor and batteries, very snappy throttle response but still quite linear, just the way I like it, and with an estimated/rated 14.6 amps of current handling ability even in an AWD the 2x2 should be able to handle just about any motor I'd want.
http://lbspd.com/v-web/gallery/albums/album164/FDS8858CZ_x_2.jpg

The Big Question:
Do I like them more than the 4562’s? Don’t know yet only time will tell, maybe. What I can say without a doubt is that I like the price, 82 cents each or $54.60 for 100 from Digi-Key, and if your looking for FETs the 8858’s are definitely worth considering.

byebye
2007.10.28, 11:04 AM
Mentioned these in a MA-010 FET thread but decided they rate their own thread after spending a day playing with them.

On paper they’re very nice with a -7.3 amp continuous drain current for the P-channel and a total P+N on-state resistance of 54.5mΩ at 4.5V, for comparison the Vishay 4562 lists a -6.2 amp continuous drain current and a total P+N on-state resistance of 58mΩ at 4.5V.

Data Sheet Link: http://www.fairchildsemi.com/ds/FD/FDS8858CZ.pdf

Max rated continuous drain current at 25° C:
N-channel 8.6 amps
P-channel -7.3 amps

On-State Resistance:
N-Channel
• Max rDS(on) = 20mΩ at VGS = 4.5V, ID = 7.3A
P-Channel
• Max rDS(on) = 34.5mΩ at VGS = -4.5V, ID = -5.6A

Of course what the manufacturer lists on the data sheet and how they actually hold up in a Mini-Z is not always the same thing but so far for me they seem to be living up to the specks. First I put a 1x1 set in an old MR-01 and after tentatively playing around with different motors I got brave enough to pop in an Atomic T2 with a 6 then eventually 7 tooth pinion to run some wall bashing 50 lap sets on a 2xWide-L RCP track. Ran out of courage at the 7 tooth pinion though, even with a listed 7.3 amps I thought anything more would be asking for a miracle, besides a T2 in a MR-01 on a small track is bit more than I can handle. The question is how long will they last as a 1x1 with a motor as hot as the T2? My guess is that even though it has now gone through 4 NiMH battery sets and nearly 400 laps it’s just plain lucky to be alive.

After the MR-01 I put a 2x2 in a MA-010 with one of the blue MZWS BB practice motors (I believe it’s a 47 turn); noticeable power increase over the 3010’s with the same motor and batteries, very snappy throttle response but still quite linear, just the way I like it, and with an estimated/rated 14.6 amps of current handling ability even in an AWD the 2x2 should be able to handle just about any motor I'd want.
http://lbspd.com/v-web/gallery/albums/album164/FDS8858CZ_x_2.jpg

The Big Question:
Do I like them more than the 4562’s? Don’t know yet only time will tell, maybe. What I can say without a doubt is that I like the price, 82 cents each or $54.60 for 100 from Digi-Key, and if your looking for FETs the 8858’s are definitely worth considering.

Great write up!

Kris

dohc
2007.10.28, 11:17 AM
need help with fet specs. how will i go about comparing these new fets of yours against the irf 7389? i have no clue where to look -,-

data sheet

http://www.irf.com/product-info/datasheets/data/irf7389.pdf

thanks

LBRC
2007.10.28, 08:16 PM
need help with fet specs. how will i go about comparing these new fets of yours against the irf 7389? i have no clue where to look -,-

data sheet

http://www.irf.com/product-info/datasheets/data/irf7389.pdf

thanks
Not sure it can be done in a 10,000 words or less?!!

With most of the FETs we use comparing the total on-state resistance for both the P and N channels and the mosfets max continuous current drain will tell you 98% of what you need to know.

On-State Resistance or “rDS(on)” will give you an idea of how efficient the mosfet is, the lower the value the more battery power reaches the motor. Putting mosfets in parallel reduces the resistance by half so that a 2x2 will have half the resistance of a 1x1, the practical result being that a car with a 2x2 will be faster than the same car with a 1x1 of the same mosfets.

Maximum Continuous Current will give you an idea of how much current the motor can draw before you see and smell smoke, so the larger the value the “hotter” the motor you can use. Not important if you are only running stock class motors but very important if you wish to run low turn hot motors.

For the motor to go in one direction the car needs to use both a P and an N channel.
• So for total resistance you need to add the P and N channel On-State Resistance.
• And for current handling ability the weakest link sets the limit so only the P-channel matters since being the lowest it will burn out first.

Typically you would compare the 8858’s 20 milliohm N-channel resistance at 4.5 volts and its 34.5 milliohm P-channel resistance at 4.5 volts, totaling a nice and low 54.5 milliohms to the 7389’s 46 milliohm N-channel resistance at 4.5 volts and 98 milliohm P-channel resistance for a total of 144 milliohms.

Compare total P+N-channel resistance at 4.5 volts:
• 8858 = 54.5mΩ for a 1x1 and 27.25 mΩ for a 2x2
• 7389 = 144mΩ for a 1x1 and 72mΩ for a 2x2

And P-channel continuous drain current:
• 8858 = -7.3A for a 1x1 and -14.6A for a 2x2
• 7389 = -5.3A for a 1x1 and -10.6A for a 2x2

So usually that would be all you’d need to know, as you can see a 2x2 7389 would still have more rated resistance than a 1x1 of the 8858’s while only handling 3.3 more amps, and even worse at 3x3 the 7389 would start to look ridiculous only handling 1.3 more amps than a 2x2 of the 8858s while still having noticeably more resistance...

However things are not quite so simple with the IRF 7389 it takes much more to see what is actually going, yes at first glance the on-state resistance will seem high and the current handling good but not great when in fact because of power dissipation and switching it’s actual performance in a Mini-Z is quite a bit better than that type of quick uneducated glance at a data sheet would lead you to suspect. Cold as seen above it can’t compare to the 8858 or a 4562 but in some cases where they are hot in the middle of a race and consequently less efficient due to the increased resistance a 7389 is able to stay cooler with consequently lower resistance values.

The other problem is with stacking, data sheets rarely give a good indication about what will happen when you run a particular mosfet in parallel without modifying the driver circuitry too, yet alone what happens when you plop one right down on top of the other, something the manufacturer never intended. I am/was a 7389 fan for 2x3 and 2x4 stacks preferring them to the 4562’s especially in a 2x4+ stacks, however the more mosfets in a stack the greater the chance something will go wrong and with the right mosfet there is rarely a true need for a 2x3 or 2x4 stack.

For racing things become even more complicated since the “fastest car” and best lap times rarely have anything to do with each other. Things like how the mosfet and motor combo responds to the throttle movement are just as, if not more important, than resistance, current handling ability, speed, and power. Unfortunately that’s nearly impossible to find on a data sheet it’s a mater of trial and error to see what works for you.

dohc
2007.10.28, 10:29 PM
thanks a lot for the information. i learn new things everyday ;]

byebye
2007.10.28, 10:45 PM
LBRC that was the most infomative info about FETs I've ever heard. Good on ya! Also why I stickied it ;)

Kri

Breeze
2007.10.31, 04:42 PM
Quoted by LBRC "and with an estimated/rated 14.6 amps of current handling ability even in an AWD the 2x2 should be able to handle just about any motor I'd want."

I happen to disagree with the seemingly wide spread opinion that stacking FET's increases the current capacity. I beleive that stacked FET's are still only good up to the current capacity of a single FET, but the load is placed across both FET's and therefore the FET can run cooler. I don't think the motors we use pull more than 2 to 3 amps, anyway. We do get the benefit of reducing the resistance with stacking. To increase the current capacity the FET's would have to be wired in series.

LBRC
2007.11.01, 01:43 PM
Have been trying to figure out how to be nice and break it to you gently but it’s sort of like trying to explain when someone posts with conviction that the world is flat.

Stacking the mosfets puts two or more in parallel, and even without any formal electronic education you should be able to see how with two working side by side the current handling ability of the circuit is doubled since you then have two mosfets sharing the same load instead of just one. As for the “series” statement mosfets are not batteries that’s the sort of nonsensical statement that shows you lack an understanding of basic electronic fundamentals to the point what a mosfet is and how it works.

What I suggest you do is to pick up an Atomic T2 or 33 turn PN Racing Anima motor to install in a Mini-Z for a few hard laps around a track, after the smoke clears try it with a stacked set of mosfets.

Now you could make a good argument by saying that power handling, as in watts, and heat dissipation is the real problem, while max continuous current on the data sheet is just a quick easy indication of how the proposed set of FETs will do, the goal being to get as much power through the mosfets and to the motor as possible while driving without overheating and destroying the mosfets in the process and reducing rds(on) by placing the mosfets in parallel is the key to the power equasion. It’s true that we don’t run high amperage continues current through the mosfets, heck I doubt the circuit board pathways could take it, it’s the constant spiking and stall current that kills our mosfets, but technicalities aside the fact remains that putting the mosfets in parallel by stacking allows us to double the current handling ability of the ESC on the circuit board.

byebye
2007.11.01, 05:45 PM
Well said LBRC...

Kris

2EZ
2007.11.02, 09:51 AM
The more I learn the more I know I don't know!!

This is what makes the forums interesting
2EZ

Breeze
2007.11.02, 11:06 AM
Have been trying to figure out how to be nice and break it to you gently but it’s sort of like trying to explain when someone posts with conviction that the world is flat.

Stacking the mosfets puts two or more in parallel, and even without any formal electronic education you should be able to see how with two working side by side the current handling ability of the circuit is doubled since you then have two mosfets sharing the same load instead of just one. As for the “series” statement mosfets are not batteries that’s the sort of nonsensical statement that shows you lack an understanding of basic electronic fundamentals to the point what a mosfet is and how it works.

What I suggest you do is to pick up an Atomic T2 or 33 turn PN Racing Anima motor to install in a Mini-Z for a few hard laps around a track, after the smoke clears try it with a stacked set of mosfets.

Now you could make a good argument by saying that power handling, as in watts, and heat dissipation is the real problem, while max continuous current on the data sheet is just a quick easy indication of how the proposed set of FETs will do, the goal being to get as much power through the mosfets and to the motor as possible while driving without overheating and destroying the mosfets in the process and reducing rds(on) by placing the mosfets in parallel is the key to the power equasion. It’s true that we don’t run high amperage continues current through the mosfets, heck I doubt the circuit board pathways could take it, it’s the constant spiking and stall current that kills our mosfets, but technicalities aside the fact remains that putting the mosfets in parallel by stacking allows us to double the current handling ability of the ESC on the circuit board.

Well Now, I stand corrected, but man you are brutal! :(

CristianTabush
2007.11.08, 12:36 PM
good stuff!!!

Felix2010
2007.11.10, 03:38 PM
Seems now there are a few more very viable FETs out there besides the venerable 4562. Very interesting. :D

ruf
2007.11.15, 02:35 AM
Any thoughts re: input capacitance? I've been rethinking my stance on linearity vs. driveability.

pinoyboy
2007.12.11, 12:17 AM
I was able to try some of these on an F1. I received the car with an kyosho X-speed and 3004 fets. This thing was a dog :p I thought that it might just be a problem with the car. So, I changed to a NIP Speedy 05, but it still was ridiculously slow off the line and speed was really low. I began to think this car had some type of board problem, but I decided to change the fets to see if it made a difference


http://i138.photobucket.com/albums/q264/hescobal/2x2f1fet003.jpg
I went straight to a 2x2 stack since I did not want to mess around with the board too much fearing I might lift a pad. Anyways, the fet job went well. The car now had much better punch that was controllable and decent speed for a car that weighs the same as an MA-010. I later stole my bros HFAY motor :p and it felt really nice in the car with more punch and speed.

I have a fetted 2x2 4562 MR-02 and I know its not a direct comparison, but it would be hard to figure what each car had. I'd definitely recommend these for the price alone. I will possibly get a chance to run a decent mod motor soon, but with the fets rating, I don't think its hot enough to really see what they can take.

I've heard a 2x2 stack of 4562 fets can take an anima in an mr-02, so these should possibly take something with lower turns :confused: but for most of us, anything lower would probably be useless for circuit racing

BryceVR
2007.12.15, 01:33 AM
Great info LBRC,
Our local Mini-Z guy swears by the SP8M4.
As I am going to FET about 4 cars soon and don't want to do it again, the hassle factor is way more expensive than the chips so it's worth getting it right the first time. Which would be the better The 8858 or SP8M4? The comparison I've seen rates the SP8M4 VERY close to the 4562. I run lipos in a few cars.

LBRC
2007.12.15, 04:24 PM
Rohm SP8M4 data sheet.
http://www.rohm.com/products/databook/tr/pdf/sp8m4.pdf

Hm, very slight spec sheet P-channel current to the 8858, much higher N but since we need both a P and an N the lowest value is the weak link so not much help there, total RdsOn is extremely close.

Note the different current levels on the spec sheet test 4.5 volt test levels for RdsOn, a good example of why it’s also so hard to nail down actual in car results and why they can very so much from the spec sheets.

Me, I think you should go with the 8858’s just so you could compare the two and tell us which one you like. Or better yet do two M4’s and two 8858’s :D

BryceVR
2007.12.17, 11:09 AM
I have decided to buy 5 nano racers and set them all up as test beds, they are an absolute clone of of a MR02 and are cheap enough to make mistakes affordable.
I've just become serious about small scale and I reckon if I could blow 60-70 grand over the years on planes trains and automobiles I can blow a few a few K getting this right. I am building a 4 point scale wind tunnel so a few bucks on FET's won't tickle the the budget too far. My biggest problem is getting enough space for a full time track with enough length.
Talking about FETs, it's a bit like what oil do you use? What Beer do you drink? 12 people = 12 answers. It's the same in the bigger scales as a lot of you know.
I guess I'll "suck it and see"
Get back to you.
Check the "do spoilers work" thread for up dates on the wind tunnel.

dameetz
2008.03.15, 11:47 AM
Where can I get this 8858 fets?

LBRC
2008.03.15, 04:55 PM
An on-line electronic supply warehouse like DigiKey, or just about any local electronic supply store in the US can order Fairchild products (true electronic store though not a Rat Shack).

Manufacturer: Fairchild
Part Number: FDS8858CZ

Note
The part number is important, you need to make sure the "8858" you are ordering is not an older NDS8858H or an "8958" series both of which would work but be disappointing with much higher resistance and lower current handling abilities.

dameetz
2008.03.16, 12:04 AM
An on-line electronic supply warehouse like DigiKey, or just about any local electronic supply store in the US can order Fairchild products (true electronic store though not a Rat Shack).

Manufacturer: Fairchild
Part Number: FDS8858CZ

Note
The part number is important, you need to make sure the "8858" you are ordering is not an older NDS8858H or an "8958" series both of which would work but be disappointing with much higher resistance and lower current handling abilities.

I just been to DigiKey web and under the Item Number key they listed either FDS8858CZCT-ND or FDS8858CZ. So according to your advice above it is the FDS8858CZ to choose right? The minimum order is 2500 pieces. Is there anywhere I can just get like 10 or 20 pieces?

pinoyboy
2008.03.16, 12:30 AM
I ordered mine through mouser
http://www.mouser.com/Search/ProductDetail.aspx?R=FDS8858CZvirtualkey51210000vi rtualkey512-FDS8858CZ

Cheaper than Digi key. They shipped them out quickly too

LBRC
2008.03.16, 02:06 AM
The above Mouser link looks like a good deal especially since DigiKey has a surcharge for orders under $25.

As for DigiKey you are looking at the DigiKey part number instead of the Manufacturer’s PN, if you look again you’ll notice that they are all the same manufacturer PN just in different packages the “TR-ND” at the end of the DigiKey PN stands for Tape & Real while “CT-ND” stands for Cut Tape which is what you would want to order, an individual number of mosfet packages cut off of a tape real.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=FDS8858CZCT-ND

Felix2010
2008.03.16, 10:48 AM
LBRC - I know you warned against mistakingly ordering the Fairchild 8958A Fet instead of the Fairchild 8858CZ Fet. I was looking at the specifications for each of these two Fets on DigiKey and in the "Package/Case" column, for the 8958A Fet it says "8-SOIC" ; For the 8858CZ it says "SO-8". Could you tell me what this means? I have heard of the SO-8 package before, but I don't know what it is. Is the "SO-8" package superior?
I have seen the 8958A Fets for sale at EGRmart and I'm curious as to why the 8958A Fets are being sold by a Mini-Z hop-up site over some of the other "new" Fets out now like the 8858CZ and the Rohm SP8M4? Are there some good points about the 8958A Fets that we are overlooking? Just wondering, I am definitely not and expert on FETs.:)
Thanks for the great FET-info too, LBRC :D

dameetz
2008.03.16, 10:51 AM
Thanks for the above link, will try to order it from mouser.

kja812
2008.03.16, 02:30 PM
Could you tell me what this means? I have heard of the SO-8 package before, but I don't know what it is. Is the "SO-8" package superior?

SO-8 and SOIC-8 referr to the same 8 lead package.

LBRC
2008.03.16, 11:30 PM
...I have seen the 8958A Fets for sale at EGRmart and I'm curious as to why the 8958A Fets are being sold by a Mini-Z hop-up site over some of the other "new" Fets out now like the 8858CZ and the Rohm SP8M4? Are there some good points about the 8958A Fets that we are overlooking? ...

Somebody tried and liked them, supply, demand, availability? Got a good deal on a couple of thousand and now have to sell all 2+K before selling anything else, no way of really knowing. I posted the info on these because they seem to work well, but above all are cheep and easy to get in the US, EGR being in HK who knows…

One thing to keep in mind about different mosfets is that they do feel slightly different so when it comes to replacing stock or blown FETs as long as the new set or stack will handle a particular car/motor’s current needs the “best” with some concession to resistance usually ends up being a matter of personal preference. :o Even then I might like the way one FET with superior specks “feels” but the lap timer may actually prefer a mosfet with less impressive specs.

Felix2010
2008.03.17, 07:08 AM
kja812 - Thanks for answering my "SO-8 / SOIC-8" question.

LBRC - Thanks again for all the great Fet info. I hope to get a hold of some of the Fairchild 8858CZ Fets you recommended.:D

Felix2010
2008.03.17, 12:55 PM
@LBRC - While I was shopping for some 8858CZ Fets using the link provided by pinoyboy(Thank you:D), I did a search for the 8958A Fets and there were three versions listed. One was listed as "obsolete", but the other two were In-Stock: One FET was listed as manufacturer part#512-FDS8958A_Q and the other was listed as manufacturer part#512-FDS8958A . The prices for these FETs are different: The 512-FDS8958A_Q version costs $1.57 per Fet; The 512-FDS8958A version costs $3.03 per Fet. I am thinking about ordering a few of these 8958A Fets to try when I order the 8858CZ Fets - Could you tell me which one is the "correct" 8958A Fet that I should purchase? Thank you!:D

LBRC & pinoyboy - Are there any other Fets that you recommend I should look at buying to try on Mini-Zs while I'm here placing an order?

kja812
2008.03.17, 03:30 PM
I checked mouser's site for you.

The _Q parts are non-lead free while the other parts are newer lead-free production parts. Save the couple bucks and order the _Q parts.

Looks like they have stock of the ever popular Vishay SI4562DY.

They also have stock of a few other Fairchild parts that aren't quite as good as the two you're looking at: FDS4897/FDS8960/FDS8962/FDS4885.

Hope this helps.

LBRC
2008.03.17, 04:17 PM
Edit: woops, too late and too long:o
...I did a search for the 8958A Fets and there were three versions listed. One was listed as "obsolete", but the other two were In-Stock: One FET was listed as manufacturer part#512-FDS8958A_Q and the other was listed as manufacturer part#512-FDS8958A . The prices for these FETs are different: The 512-FDS8958A_Q version costs $1.57 per Fet; The 512-FDS8958A version costs $3.03 per Fet. I am thinking about ordering a few of these 8958A Fets to try when I order the 8858CZ Fets - Could you tell me which one is the "correct" 8958A Fet that I should purchase? ...
They are both the same mosfet, the only difference is that the $3.03 version is guaranteed meet the following criteria:

RoHS (EU Directive 2002/95/EC) the maximum concentration values of the restricted substances by weight in any homogenous materials are:
• Cadmium/Cadmium Compounds 0.01%
• Hexavalent Chromium/ Hexavalent Chromium Compounds 0.10%
• Lead/Lead Compounds 0.10%
• Mercury/Mercury Compounds 0.10%
• Polybrominated Biphenyls (PBBs) 0.10%
• Polybrominated Biphenylethers (PBDEs)0.10%

While the $1.57 may still not contain any of the above listed materials in the prohibited quantities but has no guarantee.

I'd go for the $1.57.


LBRC & pinoyboy - Are there any other Fets that you recommend I should look at buying to try on Mini-Zs while I'm here placing an order?

If you are experimenting with different FETs IMO you need a bench mark and that’s the Vishay SI4562DY since it set the standard, but unfortunately is becoming hard to find.

Then there’s the IRF 7389 it’s the odd FET, gets a bum wrap because the peeps want max current and lowest resistance on a data sheet to tell the whole story.

Haven’t’ tried any but the Rohm SP8M4 looks interesting.

BTW
Awhile back a put a 1x1 set of the 8858’s in an old MR-01 along with an Atomic T2 and 6 tooth pinion, and left it by the track for anyone to drive since I haven’t had much time to play lately, the good news is that surprisingly the FETs are still in good shape, the bad is that no servo saver and a T2 on a relatively small track for anyone to drive…ouch not sure how much use it got before the servo baught the farm.

Felix2010
2008.03.18, 07:27 AM
I checked mouser's site for you.

The _Q parts are non-lead free while the other parts are newer lead-free production parts. Save the couple bucks and order the _Q parts.

Looks like they have stock of the ever popular Vishay SI4562DY.

They also have stock of a few other Fairchild parts that aren't quite as good as the two you're looking at: FDS4897/FDS8960/FDS8962/FDS4885.

Hope this helps.
kja812 - Thank you, this info helps a lot. Out of the four other Fairchid parts you listed, the one that I know a good friend of mine had good experience with was the FDS8962. I will probably grab some of these. I have some Si4562DY's hanging around, but they're good to have - I'll check them out on mouser. Thanks again:D

Felix2010
2008.03.18, 07:57 AM
Edit: woops, too late and too long:o

They are both the same mosfet, the only difference is that the $3.03 version is guaranteed meet the following criteria:

RoHS (EU Directive 2002/95/EC) the maximum concentration values of the restricted substances by weight in any homogenous materials are:
• Cadmium/Cadmium Compounds 0.01%
• Hexavalent Chromium/ Hexavalent Chromium Compounds 0.10%
• Lead/Lead Compounds 0.10%
• Mercury/Mercury Compounds 0.10%
• Polybrominated Biphenyls (PBBs) 0.10%
• Polybrominated Biphenylethers (PBDEs)0.10%

While the $1.57 may still not contain any of the above listed materials in the prohibited quantities but has no guarantee.

I'd go for the $1.57.



If you are experimenting with different FETs IMO you need a bench mark and that’s the Vishay SI4562DY since it set the standard, but unfortunately is becoming hard to find.

Then there’s the IRF 7389 it’s the odd FET, gets a bum wrap because the peeps want max current and lowest resistance on a data sheet to tell the whole story.

Haven’t’ tried any but the Rohm SP8M4 looks interesting.

BTW
Awhile back a put a 1x1 set of the 8858’s in an old MR-01 along with an Atomic T2 and 6 tooth pinion, and left it by the track for anyone to drive since I haven’t had much time to play lately, the good news is that surprisingly the FETs are still in good shape, the bad is that no servo saver and a T2 on a relatively small track for anyone to drive…ouch not sure how much use it got before the servo baught the farm.

LBRC - Excellent write-up, as always. I appreciate the detail you go into, I am a believer you can never have too much good info.:D
I had a 2x2 4562 stack put on an AD-PCB for me by a good friend who is a soldering master... The boards come back to me looking like they came from the factory made especially for me.:cool: I liked the 4562's a lot, no problems/negatives whatsoever IMO. I just recently had this same friend replace the 2x2 4562 stack with a 2x3 SP8M4 stack on the AD-PCB, and my initial testing has been excellent. For a while now I have been trying different hand pattern-wound motors made by Top Secret Motor's proprietor Flashsp-2 - (Just a lil' TSM plug - Really, really good stuff:)). Sometimes the motors I run go beyond the Anima/Chili/T2 current flow and I upgraded so I could handle basically any motor I want in my AD-MA010.
But an FET-expert I am not, so all the info you provide is very much appreciated. I read the beginning of this thread about your 8858-Fetted MR-01 with the T2, and now that you've mentioned it still is up and running, the 8858CZ's I will have to try. I like how you said the 8858CZ's have a snappy-but-linear throttle feel also.
The Vishay 4562's I should grab since you wrote they are becoming harder to find.
I have not tried the IRF 7389 because of the popularity of the 4562. I haven't been in the Mini-Z arena for that long and I never investigated into the 7389. With the other Fets like the 8858CZ I am looking at and trying, I don't know if I'll have time for the 7389 - Maybe if they make a comeback:).
So many Fets, so little time...

Flashsp-2
2008.03.18, 09:25 AM
I had a 2x2 4562 stack put on an AD-PCB for me by a good friend who is a soldering master... The boards come back to me looking like they came from the factory made especially for me.:cool: ... For a while now I have been trying different hand pattern-wound motors made by Top Secret Motor's proprietor Flashsp-2 - (Just a lil' TSM plug - Really, really good stuff:)).

Aww thanks bro :D

I haven't tried the 8858, but I did try the 8962 (2x2) for bit, as well as running stacked 3010s. The 8962 were actually quite good, the throttle was pretty linear, which is my primary concern when upgrading boards. I think the general consensus on the 3010 is great in terms of driveability, so I won't beat that horse anymore. I currently have a 2x3 SP8M4 on my AD mr02, and I love them. The throttle feel is excellent, and the power is very broad, no matter where you get on it, the car has go-juice. Even with the 2x3 it isn't switchy feeling at all, which was a big concern with changing from the 2x2 3010 of the AD. I would really like to see someone review both the 8858 and the SP8M4 back-to-back, I think that would be very interesting to see.

Felix2010
2008.03.18, 11:13 AM
Aww thanks bro :D

You're welcome.:D

...I would really like to see someone review both the 8858 and the SP8M4 back-to-back, I think that would be very interesting to see.

Sounds like a nice future project, maybe? :D

Aurora
2008.05.25, 11:20 PM
LBRC,

Thanks for the writeups, and just like to share with you my findings on these fets:

I have recently stacked 2x2 forward, 2x2 backward FDS8858CZ fets (total of 8) to my ASF 2.4G for testing. But the result is rather mysterious. The car will have a slight delay of less than a sec, when under acceleration, then it will just 'shoot off'.

Original plan is simply to have a 2x2 forward and 2x1 for backwards. But the car is behaving as said, and I wonder whether the imbalance of fet numbers is the cause. But even adding two extra to backward, the same problem persist.

Local experts, though not familiar with this fet, has told me that sometimes a fet will behave differently during acceleration/top speed/deceleration, and what looks good on paper doesn't always translate to real-life application. (which I think is genuinely true).

Have you observed any performance suffering after heavy usage of these fets? And any side effect of stacking them more than 3?

EMU
2008.05.26, 12:47 AM
Have you tried a single layer on the forward and reverse (4 fets total)?

dameetz
2008.05.26, 10:51 AM
LBRC,

Thanks for the writeups, and just like to share with you my findings on these fets:

I have recently stacked 2x2 forward, 2x2 backward FDS8858CZ fets (total of 8) to my ASF 2.4G for testing. But the result is rather mysterious. The car will have a slight delay of less than a sec, when under acceleration, then it will just 'shoot off'.

Original plan is simply to have a 2x2 forward and 2x1 for backwards. But the car is behaving as said, and I wonder whether the imbalance of fet numbers is the cause. But even adding two extra to backward, the same problem persist.

Local experts, though not familiar with this fet, has told me that sometimes a fet will behave differently during acceleration/top speed/deceleration, and what looks good on paper doesn't always translate to real-life application. (which I think is genuinely true).

Have you observed any performance suffering after heavy usage of these fets? And any side effect of stacking them more than 3?

Do as Emu suggested, as I m having no delay problem with mine in two of my ASF cars fitted with 8858CZ.

hilldebrandt
2008.11.04, 04:04 PM
I ordered mine through mouser
http://www.mouser.com/Search/ProductDetail.aspx?R=FDS8858CZvirtualkey51210000vi rtualkey512-FDS8858CZ

Cheaper than Digi key. They shipped them out quickly too

I just looked at the Mouser site. None available, they are on backorder :



Mouser Part #: 512-FDS8858CZ
Mfr.'s Part #: FDS8858CZ
Description: MOSFETs 30V Dual N & P-Ch PowerTrench MOSFET

Mouser Product Availability

No Stock
4,866 On Order
Estimated Ship Date

2,366 12/2/2008

2,500 12/22/2008


Factory Lead Time

11 Weeks

Felix2010
2008.11.06, 11:01 PM
I was on mouser's website the other day, I did a search for 4562's - They're out-of-stock, but mouser listed 4511 as a possible replacement. There's an old thread from 2003 or something where someone aksed about 4511's, but no one replied.
Any FET guys have any thoughts on Vishay Si4511DY FETs?:)

gnehcoel
2008.11.11, 02:09 AM
I have a question for the MR02 ASF. Since the 8858 and 4562 are both sold out ... I just wonder if the 8962 mentioned by Flashsp is a good temporary replacement?

Thanks.

Felix2010
2008.11.11, 02:20 AM
Flash knows his stuff, and I know he said the 8962 fets performed well for him. You can trust his opinion. I have heard the 8962's are similar in spec to the 4562's; I believe Flash verified this, he runs some hot motors sometimes (He winds his own custom motors, excellent stuff - Look up "Top Secret Motors").
If you find them, a better Fet still would be the SP8M4 by Rohm. They are for sale at a few places, try googling them. Flash and I both agree that the SP8M4 Fets are among the best Fets out right now. Also, I believe the 8858's can be found in-stock at Reflex Racing. The 8858's and SP8M4 Fets are considered very close in performance, so either would be a solid choice.
Hope this helps

gnehcoel
2008.11.11, 03:21 AM
Thanks Felix. Perfect timing ... I just finished reading about the 8962 FETs thread by Flash, CT and a few others ... very interesting. Seems like 8962 is better than 3010 (in some people's opinion) and not as great as 8858 and 4562 ... thanks again :)

hilldebrandt
2008.11.27, 07:28 PM
The 8858's are back in stock at Mouser ! :D

http://www.mouser.com/Search/ProductDetail.aspx?R=FDS8858CZvirtualkey51210000vi rtualkey512-FDS8858CZ

Action B
2008.11.29, 02:00 PM
The 8858's are back in stock at Mouser ! :D

http://www.mouser.com/Search/ProductDetail.aspx?R=FDS8858CZvirtualkey51210000vi rtualkey512-FDS8858CZ

True, I ordered some last week. Now my car has 8858 FETs on it!

hilldebrandt
2008.11.29, 08:11 PM
Mine were shipped yesterday. I ordered 100 of them...should keep me busy for awhile !!
Except for the 2.4 that I just got, all my boards still have the 3004 fets on them.
So needless to say ,I needed some upgrades !! LOL

Action B
2008.12.01, 01:24 AM
Mine were shipped yesterday. I ordered 100 of them...should keep me busy for awhile !!
Except for the 2.4 that I just got, all my boards still have the 3004 fets on them.
So needless to say ,I needed some upgrades !! LOL
A hundred FETs? What are you going to do with a HUNDRED FETS?

hilldebrandt
2008.12.01, 02:26 PM
A hundred FETs? What are you going to do with a HUNDRED FETS?

Why I'm going to put an OUTRAGEOUSLY INSANE stack of 50x2 on a Mod car and eat all the other Mr02's for breakfast !! :eek::eek:
*burp........ LMAO

Seriously...since I noticed that they seem to be out of these fets for months at a time, I figured that I'll get a bunch now so I have them for any future projects. Plus I'll have alot of extra's if the DOW gang need any, too.

andreophile
2008.12.01, 03:25 PM
For a moment you almost had me believing that you're trying to build a scale replica of the WTC Twin Towers on your PCB :p

Action B
2008.12.01, 04:05 PM
Honestly, I thought my purchase of 25 was excessive lol. I only use 4 per car.. then again, my club is probably smaller than yours. Also, I only have one car.

hilldebrandt
2008.12.01, 05:11 PM
For a moment you almost had me believing that you're trying to build a scale replica of the WTC Twin Towers on your PCB :p

LOL
That would look hysterical with twin towers sticking up through the roof ! :eek:


Honestly, I thought my purchase of 25 was excessive lol. I only use 4 per car.. then again, my club is probably smaller than yours. Also, I only have one car.

I ran with Dow for just a few races almost 2 years ago.I had a Mr01 and a Mr02, each with 3004 fets. I also bought back then but never raced two F1's, each with 3004's also. (A LHS was selling out and I got some good deals)

I just got an ASF 2.4 Mr02 and I want to upgrade the fets on the others so I can start racing on a regular basis again. Plus I have a few other projects that I want to tinker with....;)

LBRC
2008.12.02, 02:10 AM
LOL
That would look hysterical with twin towers sticking up through the roof ! :eek:
:D
http://lbspd.com/v-web/gallery/albums/album09/MVC_012X.jpg

hilldebrandt
2008.12.03, 05:32 PM
^^Kewl !!

But ya forgot to add the high power antennas on the roof of one of the towers ! :p LOL

mleemor60
2009.05.03, 11:33 AM
Has anybody successfully been able to triple stack an AM board with 8858's? I recently heard third hand that it won't work and have seen first hand the room full of smoke accompanied by that lovely aroma. With the PN rules being what they are now and people trying to hold on to old technology some have felt the need to stack them high to stay even with the 2.4's with a 70T motor.

civilian
2009.09.15, 05:03 PM
can this new kid stands Li-Ion/Li-Poly 7.4v 2200maH?
BTW i'm talking about MA-010 AM board and ASF too.

i have both and planning to stacked 8858 on each of them.

i need info please.

thanks in advance.

civilian
2009.09.15, 05:11 PM
can this new kid stands Li-Ion/Li-Poly 7.4v 2200maH?
BTW i'm talking about MA-010 AM board and ASF too.

i have both and planning to stacked 8858 on each of them.

i need info please.

thanks in advance.

color01
2009.09.16, 05:51 AM
Datasheet suggests it can take 30V, if I'm not mistaken. Completely 2S LiPo safe. ;)

civilian
2009.09.17, 01:59 AM
Datasheet suggests it can take 30V, if I'm not mistaken. Completely 2S LiPo safe. ;)

thanks!
i give a try.
just a matter of time :p

fraga
2010.11.07, 05:23 PM
So if I can get 8858 at about the same price of 8962, is there any argument to go with 8962?

fraga
2011.01.17, 02:40 AM
Has anybody successfully been able to triple stack an AM board with 8858's? I recently heard third hand that it won't work and have seen first hand the room full of smoke accompanied by that lovely aroma. With the PN rules being what they are now and people trying to hold on to old technology some have felt the need to stack them high to stay even with the 2.4's with a 70T motor.

Yes, I have and they are working with no problems.

Jshwaa
2015.02.09, 09:19 AM
Just curious.

How do they regulate FET upgrades at racing events?

Do they make you physically show them your stock FET's, or is it just stacking that's against the rules?

arch2b
2015.02.09, 03:43 PM
dependent entirely on class rules and the rules vary everywhere.

dameetz
2015.02.09, 08:55 PM
Is this (8858cz) still the best fet available for mini z after all these years?

byebye
2015.02.09, 10:39 PM
Is this (8858cz) still the best fet available for mini z after all these years?

Of the FETs I've seen in this scene 8858 has the best specs in terms of volts and amps.

Jshwaa
2015.02.09, 10:49 PM
Is this (8858cz) still the best fet available for mini z after all these years?

I would beg to differ, but 8858's have definitely built some confidence from what I've read, so go with it. :cool:

dameetz
2015.02.10, 09:58 AM
I was just browsing mouser site and found this one si4501 (http://www.mouser.com/Search/ProductDetail.aspx?qs=biNArH83b7M106kS%2f4NiCg%3d% 3d)? Is this the same type of fet that our miniz pcb can use? Is the spec better than 8858?

TheSteve
2015.02.10, 02:29 PM
I was just browsing mouser site and found this one si4501 (http://www.mouser.com/Search/ProductDetail.aspx?qs=biNArH83b7M106kS%2f4NiCg%3d% 3d)? Is this the same type of fet that our miniz pcb can use? Is the spec better than 8858?

The 4501 can be used but I'd prefer the 8858 to it. But then I also prefer the 4562 to the 8858.