An improved 2n7002

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2n7002k.

http://www.vishay.com/docs/71333/2n7002k.pdf
Crss and Coss are about halved compared to the old-guard part,
the rest of the specs eyeball out about the same.  Rdson may be
a tad lower, depending on Vgs & such. YMMV.

I may have to drive some switches at 15MHz, so low Crss is appealing.

Several mfrs make 'em. Gate's protected, too.

You guys would like the very nice OnSemi datasheet I have for
the OnSemi version. Online I only the see the Fairchild version
though -- not as detailed & helpful.


Cheers,
James Arthur

Re: An improved 2n7002
On Wed, 9 Oct 2019 20:27:14 -0700 (PDT), snipped-for-privacy@yahoo.com
wrote:

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I've got some products where the classic 2N7002 is better than any
more modern stuff we've tried. In particular, the Fairchild part will
switch 50 volts in under 1 ns, wildly different from what the data
sheet suggests.

The K version would be interesting to try for fast switching. I wonder
how gate protection might affect switching speed.

In the Vishay data sheet above, the Output and Transfer curves on
sheet 3 seem to disagree. The transfer curve also cruises well above
the abs max current.

(The Fairchild 2N7002 transfer curve is going great guns at 2 amps!)

Data sheets these days!



--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: An improved 2n7002
snipped-for-privacy@highlandsniptechnology.com wrote...
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 Octopart has ON Semi version if you go down to 2N7002KT1G.

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 What we need is a fast p-channel equivalent.


--  
 Thanks,
    - Win

Re: An improved 2n7002
On Thursday, October 10, 2019 at 8:05:35 AM UTC-4, Winfield Hill wrote:
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Yes, that shows the typical capacitance numbers of interest.
Thanks Win.

The OnSemi datasheet I prefer is OnSemi publication
2N7002K/D, rev. 16, October 2016 '2N7002K-D.pdf'. That
version has typical and worst-case numbers I don't see
elsewhere, not even on OnSemi's website, downloaded
three years ago. But I don't remember where I got it.

Ciss = 24.5pF typ, 45pF max.
Crss = 2.2pF typ, 5.0pF max.
Coss = 4.2pF typ, 8.0pF max.

These capacitances are already close to their minimums around
~2V.

For example, the classic Fairchild 2n7002 datasheet I've got
on my screen shows Crss = 20pF at 1V, and still 10pF at 10V.
 OnSemi's 2n7002k: Crss = 8pF/0V, 4pF/1V, and 2.5pF/10V.

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Also interesting is this Nexperia version, for its 40K/W thermal
resistance...
https://assets.nexperia.com/documents/data-sheet/2N7002BKM.pdf

As part of a much more complicated design with many moving parts
I've inherited a less-than-optimal class-C r.f. amplifier, which
prompted this bit of browsing...

Cheers,
James Arthur

Re: An improved 2n7002
wrote:

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And some fast p-GaN fets. I'm using them in totem poles, but the upper
gate driver gets really messy.

https://www.dropbox.com/s/izvf0thpe5ddty9/T577B_Vp50.JPG?raw=1





--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: An improved 2n7002
On 2019-10-10 10:41, snipped-for-privacy@highlandsniptechnology.com wrote:
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Very pretty.  Fast GaN PFETs might be possible!

<https://phys.org/news/2019-09-unveils-route-high-hole-mobility.html

Cheers

Phil Hobbs
--  
Dr Philip C D Hobbs
Principal Consultant
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Re: An improved 2n7002
On Wed, 9 Oct 2019 20:27:14 -0700 (PDT), snipped-for-privacy@yahoo.com
wrote:

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You shouldn't expect an 'improved' jedec registered part.

Variations between mfrs fabs of the same part number are a  
nuisance, if not an actual hazard - not an advantage.

You CAN find 'better' parts with different part numbers and  
that is what you should be doing, if you need parameters  
that the registered part cannot guarantee.

RL

Re: An improved 2n7002
On Thursday, October 10, 2019 at 8:47:56 AM UTC-4, legg wrote:
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I wasn't expecting an improved part, I was reporting the existence of
them. :-)

Cheers,
James Arthur

Re: An improved 2n7002

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I think some legal genius decided that one can't trademark a part
number. So LM1117 or MAX809 or whatever can be fabbed and sold by all
sorts of unsavory characters. We often specify ONSEMI ONLY or some
such for some of our stocked parts, and hope that they don't change
the recipe.

We have made deals with distributors to set aside a reel of mosfets,
send us 5 to evaluate, and sell us the same reel if we like them.




--  

John Larkin         Highland Technology, Inc

lunatic fringe electronics  


Re: An improved 2n7002
On Thu, 10 Oct 2019 07:48:44 -0700, snipped-for-privacy@highlandsniptechnology.com
wrote:

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For a 2 or 3 terminal device you should probably stick to the worst
case guaranteed performance, in multisourcing.

If you're pushing the spec beyond that, you have to generate your own
internal part number, and qualify/restrict vendors.

With more pins and internal complexity, ALL part numbers are basically
an internal qual excercise. I have to qualify at least three sources
for something as basic as a UC3842, in a new product build. I'll often
rely on past known-good triples as a starting point, but they all get
fitted extensively enough to know if they're suited to the new app.

If purchasing wants to add a vendor after the papers are finalized,
it's their tough luck - they've already got the three and there has to
be SIGNIFIGANT cost savings to justify even thinking about it, never
mind running the 'new' part through it's paces, after-the-fact. The
best you can offer is a new internal number, including the new part,
to be adopted in the 'next' product, where used. It can be vetted
then, for that new use, then possibly be worked into the older builds,
based on proven performance.

If whoever's money we're (I'm) spending says 'go do it', well, nuff
said. If it's my own nickel, I'll usually find the time to beat up a
new candidate to my own satisfaction.

The worst position you can be in, is to find out that a single-sourced
part isn't doing what it claims as a basic minimum function - you need
a completely different approach, that avoids the part entirely, in
your back pocket, as an escape route.  - and about two bushels of
unscheduled man-hours in which to make the escape.

RL



  

Re: An improved 2n7002

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All our BOMs use internal 7-digit part numbers. And every internal
part has a list of qualified vendors and their part numbers. We have a
stock bin for 2N7002 Fairchild Only. Another stock number is 2N7002
Fairchild or ON or Vishay.

We do often push specs. Like getting 1 ns out of a part whose data
sheet says it switches in 25. Sometimes we exceed abs max if the
payoff is big and we think we have margin. We can have a stock bin for
a part, and another bin for the tested part, and a test procedure.

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Engineering qualifies parts here; never purchasing.

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There are tons of sole-source parts, and some turn out to be bad. It
usually takes a board spin to fix that.


Re: An improved 2n7002
legg wrote...
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 Good advice!


--  
 Thanks,
    - Win

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