IRF part specs confusion.

[Jamie]

I go here

https://ec.irf.com/v6/en/US/adirect/ir?cmd=catProductDetailFrame&productID=AUIRF3805

and I find what I want with a ID of 210 amps@25C in a TO220AB package.

I go to various other places that show the same part and package but
all of them vary in the ID spec? None of them reach the 210 level, not
even close.

I see ID spec from 100 up to 160 Amps on the same part# in the same
package...

Also, at the posted site, if I understand what I am reading I need to
buy 50 of them * the price posted, because they sell them only in tube
quantity? I also don't see if they are actually available for immediate
shipping even though they state it's active and preferred..

Can some one clear this up for me please? I've never purchased myself
from this site.

Jamie

 

[John S]

I go here

https://ec.irf.com/v6/en/US/adirect/ir?cmd=catProductDetailFrame&productID=AUIRF3805


and I find what I want with a ID of 210 amps@25C in a TO220AB package.

I go to various other places that show the same part and package but all
of them vary in the ID spec? None of them reach the 210 level, not even
close.

I see ID spec from 100 up to 160 Amps on the same part# in the same
package...

Also, at the posted site, if I understand what I am reading I need to
buy 50 of them * the price posted, because they sell them only in tube
quantity? I also don't see if they are actually available for immediate
shipping even though they state it's active and preferred..

Can some one clear this up for me please? I've never purchased myself
from this site.

Jamie

The Id rating for your device is 160A if you can hold the case
temperature to 25C. The Id rating is the "Case Limited" value shown in
the Continuous Drain current under Absolute Maximum Ratings.

I don't know why they give the "Silicon Limited" Id values.

John S

 

[Rich Webb]

Interesting, Thanks. I had no idea about what is nucleate boiling.

Wiki to the rescue.
http://en.wikipedia.org/wiki/Nucleate_boiling
Kinda neat.

Disappointing that the article gets the delta-T values so wrong. A
temperature difference of, from the article, 4, 10, or 30 degrees C is a
*difference* of 7, 18, and 54 degrees Fahrenheit *not* 39, 50, or 86.
Somebody punched a C->F conversion button without engaging their brain.

 

[John S]

Useful for running 'short term'?

I'd rather use the SOA and transient thermal curves.

 

[Jamie]

We've been here before. All the FET companies that I know of spec
dissipation this way. It's just junction to case thermal resistance
and holding the case at that temperature so that at that dissipation,
if you could hold it at 25 C, the die would be at it's limit.

We've had several FETs above their rated die temperature limits
and seen them live. Can't usually do that for very long. Not that we
were trying to do that, except for destructive tests which are also
fun.

Reality usually has us have maximum dissipation below 10 watts or so.

Higher max die temperature and lower J-C resistance and you get to
play the higher dissipation game. Unrealistic, but a calculated number
that should be correct. IR's max die temp is 175 C so it's better
than a FET with 150 C max temperature.

As for the the TO220 Leads vs. current rating ? Over 10 years ago we
ran 150 Amps through a regular TO220 lead and it was fine. Anything
above that and it turns to slag. That's just the lead. Some newer
FETs have larger leads and some even extra source leads for lower
RDSon.

boB

I solved my problem, tonight. I decided to order 50 of these HEXFETS at
the $2.01 marked price. I Didn't need all that ID amp handling, I just
wanted something that was useable in many different things how ever,
when I hit the "Add to cart" and went to the next step to complete my
order, the price then jump to $3.65 for each, I found that distressing
and gave me a bad taste. I went over to mouser and decided on this
http://www.fairchildsemi.com/ds/FD/FDP3205.pdf

for $1.65 each.. Mouser didn't magically up the price in the middle of
the transaction. These will do fine, even though the Vgs(th) is a little
higher than the HEXFET is, around 4.0. BUt that shouldn't pose a problem
since the circuit these are going in are driving the gate at 12.

Thanks..

Jamie

 

[Wimpie]

El 07-09-11 2:43, Jamie escribió:

I solved my problem, tonight. I decided to order 50 of these HEXFETS
at the $2.01 marked price. I Didn't need all that ID amp handling, I
just wanted something that was useable in many different things how
ever, when I hit the "Add to cart" and went to the next step to
complete my order, the price then jump to $3.65 for each, I found that
distressing and gave me a bad taste. I went over to mouser and decided
on this
http://www.fairchildsemi.com/ds/FD/FDP3205.pdf

for $1.65 each.. Mouser didn't magically up the price in the middle of
the transaction. These will do fine, even though the Vgs(th) is a little
higher than the HEXFET is, around 4.0. BUt that shouldn't pose a problem
since the circuit these are going in are driving the gate at 12.

Thanks..

Jamie

Did you look to the SOA? It looks too good to be true. If I didn't
misread it, it can be nice for some linear applications.

 

[Jamie]

El 07-09-11 2:43, Jamie escribió:


Did you look to the SOA? It looks too good to be true. If I didn't
misread it, it can be nice for some linear applications.

It's all about keeping it cool.

Jamie

 

[Wimpie]

El 07-09-11 21:10, Jamie escribió:

It's all about keeping it cool.

Jamie

Jamie, look to various other mosfets (with similar power rating). It
is not just keeping it cool. You can destroy other mosfets well below
their power rating, even when you do the derating on power dissipation
for case temperature correctly.

 

[Jamie]

El 07-09-11 21:10, Jamie escribió:


Jamie, look to various other mosfets (with similar power rating). It is
not just keeping it cool. You can destroy other mosfets well below their
power rating, even when you do the derating on power dissipation for
case temperature correctly.

Yes I am aware of that, I've worked with many of these things over the
years, especially HEXFET line which is why I was trying to get those
instead. I've been very successful in implementing them into designs
with out any issues. I've run into a bad one now and then from bulk
packages. Most likely floor sweepings, who knows!

I do love it how ever when you don't take care of the ringing and
induction in the circuit. I normally place a lot of precautions in the
app to avoid such possible issues. I've seen lots of exploded packages
due to ignoring such safeguards under heavy loads in various equipment.

But most issues people have with them are just careless design problems.

Jamie