Question for Win Hill

Jim Thompson · Dec 31, 2004

Win, What N-channel MOSFET do you recommend for:

VDS max = 50V

ID max = 10mA

Typical dissipation ~ 200mW

I know, I know, dumb question, but I don't normally use *any* discrete
devices.

...Jim Thompson
--
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| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
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480)460-2350 | |
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Harry Dellamano · Dec 31, 2004

"Jim Thompson" <thegreatone@example.com> wrote in message
news

rd9t0tnsnho47805c13c6p4o8r78828v6@4ax.com...

Win, What N-channel MOSFET do you recommend for:

VDS max = 50V

ID max = 10mA

Typical dissipation ~ 200mW

I know, I know, dumb question, but I don't normally use *any* discrete
devices.

...Jim Thompson
--

Hey Jim,
I can handle any of Win's questions.
Depends how much you derate for HV but the 2N7002 in SMD or 2N7000 in
through hole are the most popular.
Happy Holidays,
Harry

John Larkin · Dec 31, 2004

On Thu, 30 Dec 2004 19:23:40 -0700, Jim Thompson
<thegreatone@example.com> wrote:

Win, What N-channel MOSFET do you recommend for:

VDS max = 50V

ID max = 10mA

Typical dissipation ~ 200mW

I know, I know, dumb question, but I don't normally use *any* discrete
devices.

...Jim Thompson

Harry's right... 2N7000/7002. Want a bagful?

I've got a little circuit we just did; it outputs 0-60 volts into 50
ohms through a 1:1 isolation transformer, using 2N7002's. Tr is just
under 2 ns at 60 volts, under 1 ns at 5.

John

Leon Heller · Dec 31, 2004

"Jim Thompson" <thegreatone@example.com> wrote in message
news

rd9t0tnsnho47805c13c6p4o8r78828v6@4ax.com...

Win, What N-channel MOSFET do you recommend for:

VDS max = 50V

ID max = 10mA

Typical dissipation ~ 200mW

I know, I know, dumb question, but I don't normally use *any* discrete
devices.

Will I do, I'm not Win?

I use the Zetex ZVN4210A, when I need an N-channel MOSFET. The ZVN4210G is
similar, but SMT.

Leon

HARRY DELLAMANO · Dec 31, 2004

"Winfield Hill" <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote in
message news:cr3jdi01nri@drn.newsguy.com...

Hah! It appears Harry and John can handle my questions just fine.
Normally I'd respond by building on their fine answers, but my P4
WinXP home computer with its datasheet collection, is dead, despite
considerable efforts to revive it, including an AMD Athlon64 3500+
mobo transplant. <sigh

Hey Win, thanks for the kind words.

Tell me about your Athlon64 3500+. I have been plugging along with a Athlon
XP 2700+ (32 BIT) for the last two years and thinking about upgrading to
64. Is it any faster for SPICE sims when operating properly?
Highest regards,
Harry

Winfield Hill · Dec 31, 2004

Jim Thompson wrote...

Tell me about your Athlon64 3500+. I have been plugging along with
a Athlon XP 2700+ (32 BIT) for the last two years and thinking
about upgrading to 64. Is it any faster for SPICE sims when
operating properly?

I have a 6-month-old Athlon64 3400+ (2.2G clock), 1GB Ram.
It is more than twice as fast as my last 1.6G P3.
BTW: P4's are _terrible_ for Spice, since Intel did away with
math-specific core... A 1G P3 is faster than a 2G P4 doing Spice.

Plus the P4's longer pipeline was very damaging. I was running a
3GHz P4, which seemed pretty snappy at Spice. However I do expect
my Athlon64 to do much better. I selected it in part because of the
"no execute" feature implemented in SP2. And was getting tired of
the increasingly power-hungry Intel processors. I have high hopes
for my 939-pin Athlon64, and I look forward to upgrading to one of
the other advanced 939-pin processors once they come down in price.

Jim, what are you working on with your little 50V 0.2W MOSFET?

--
Thanks,
- Win

Winfield Hill · Dec 31, 2004

Jim Thompson wrote...

Winfield Hill wrote:

Well, then surely you'll want viable Spice MOSFET models...

Win, Here's a bunch of models. Which would you recommend?

Anasoft-1:
Anasoft-2:
Supertex
Philips:
Ancient MicroSim:
Zetex:

Oops, I asked for that one! OK, good question, I'll retire and
consider it. But *First* I have to get my Athlon64 running, so
I can play with your selection of models, plus a few I have.
It's a good and fair question you asked. Thanks, I think!

--
Thanks,
- Win

Jim Thompson · Dec 31, 2004

On Fri, 31 Dec 2004 23:06:13 GMT, ehsjr@bellatlantic.net wrote:

Jim Thompson wrote:

On Fri, 31 Dec 2004 10:36:53 -0800, Tim Wescott
tim@wescottnospamdesign.com> wrote:

Jim Thompson wrote:

[snip]

I see so much trash audio here, that, in my "spare time", I decided I
would design an audio amplifier... class AB, but no bias pot
required... and, contrary to my thinking BJTs are better, it will be
power MOSFET output... the little device is for bias... all done just
to prove I can do it better ;-)

...Jim Thompson

[snip]

Or are you just going to make some lame claim that it's better 'cause
you actually know what you're doing with the materials at hand?

"Sounds" good to me ;-)

I may even use lamp cord to connect the speakers.

...Jim Thompson

Howinthehell are you gonna get the oxygen out of the lamp cord?

480)460-2350 | |
| E-mail Address at Website Fax

Winfield Hill · Jan 1, 2005

Jim Thompson wrote...

Sounds like load-line and/or inductive loads. I've not lost a
BJT in the field (and I used to design ignitions); not to say
I haven't killed many in the lab while designing snubbers ;-)

I've lost plenty in final application; they are in fact fragile
beasts, and the SOA is truly a killer.

--
Thanks,
- Win

Tony Williams · Jan 1, 2005

In article <3v3bt0d49opn8po1duouqn5tieepa9n0be@4ax.com>,
Jim Thompson <thegreatone@example.com> wrote:

I see so much trash audio here, that, in my "spare time", I
decided I would design an audio amplifier... class AB, but no
bias pot required... and, contrary to my thinking BJTs are
better, it will be power MOSFET output... the little device is
for bias... all done just to prove I can do it better ;-)

BJT power amplifiers are so easily destroyed by reactive loads.

--
Tony Williams.

Tony Williams · Jan 1, 2005

In article <cr3jdi01nri@drn.newsguy.com>,
Winfield Hill <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim, I should warn you that spice models for these VMOS FETs are
woefully inadequate, failing to correctly model the gate
spreading resistance, the important sub-threshold region, or
even the cascode JFET drain-capacitance scene for that matter.
They also lack any reliable thermal model. Modest analytical
calculations can often better predict a MOSFET's performance
under unusual circumstances.

Win. Are you following/understanding Cyril Bateman's
articles on modelling power MOSFETs in EW, and what
are your opinions on his approach?

--
Tony Williams.

Winfield Hill · Jan 1, 2005

Tony Williams wrote...

Winfield Hill wrote:

Jim, I should warn you that spice models for these VMOS FETs
are woefully inadequate, failing to correctly model the gate
spreading resistance, the important sub-threshold region, or
even the cascode JFET drain-capacitance scene for that matter.
They also lack any reliable thermal model. Modest analytical
calculations can often better predict a MOSFET's performance
under unusual circumstances.

Win. Are you following/understanding Cyril Bateman's articles
on modelling power MOSFETs in EW, and what are your opinions
on his approach?

I have the first three of his articles in a stack and expect the
fourth final article to arrive soon. I've glanced at them, but
clearly some concentrated study is in order. Hopefully he has
addressed two of my four issues above (the two most important to
audio amplifier designers). I have recommended his articles to
others (hoping they'll check them out). Such as yourself, Tony?

--
Thanks,
- Win

John Larkin · Jan 2, 2005

On Sun, 2 Jan 2005 08:30:19 -0800, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

Don Lancaster said, "an hour in the library is worth a week in the lab",
and learning from others' mistakes was prudent and timesaving. (or did
he say a day in the lab? - whatever.)

The other one I like is...

"One test result is worth one thousand expert opinions"
- Wernher von Braun

John

Ken Smith · Jan 2, 2005

In article <1gvYOcEz0D2BFw7H@jmwa.demon.co.uk>,
John Woodgate <noone@yuk.yuk> wrote:

I read in sci.electronics.design that John Larkin <john@spamless.usa
wrote (in <5degt05mckp1r7g8091v3n9m60t7hgfq09@4ax.com&gt about 'Question
for Win Hill/ Athlon64', on Sun, 2 Jan 2005:
It is highly unprofessional to simplistically reduce the size of the
heatsink based on the statistics of audio waveforms. Serious audio
designers know that one must simultaneously reduce the size of the power
transformer and the filter caps to maintain the coveted peak-music-power
rating.

Heresy!!!!!

By all means reduce the transformer,

No, the power transformer *MUST* be a toroid.

--
--
kensmith@rahul.net forging knowledge

John Larkin · Jan 3, 2005

On Sat, 1 Jan 2005 22:02:58 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that John Larkin <john@spamless.usa
wrote (in <s16et0lsq4kng0vdt92gna0m8qkbjekqbb@4ax.com&gt about 'Question
for Win Hill', on Sat, 1 Jan 2005:

Beautiful. I wish more people would do this.

Oh, you can spice things like this...

thermal == electrical

1 K/w == 1 ohm

Or in proper SI symbols (too bad about the ohm!):

1 K/W == 1 ohm

1 w == 1 amp

1 W == 1 A

1 k == 1 v

1K == 1 V

1 sec == 1 sec

1 s == 1 s

1 gram aluminum == 1 farad

1 gm Al == 1 F

I stand corrected. And annoyed.

John

Terry Given · Jan 2, 2005

John Woodgate wrote:

I read in sci.electronics.design that John Larkin <john@spamless.usa
wrote (in <5degt05mckp1r7g8091v3n9m60t7hgfq09@4ax.com&gt about 'Question
for Win Hill/ Athlon64', on Sun, 2 Jan 2005:

It is highly unprofessional to simplistically reduce the size of the
heatsink based on the statistics of audio waveforms. Serious audio
designers know that one must simultaneously reduce the size of the power
transformer and the filter caps to maintain the coveted peak-music-power
rating.

Heresy!!!!!

By all means reduce the transformer, but the filter caps MUST be each
100000000 uF, military grade, gold-plated if you can't get mithril, and
at least six in parallel.

ROTFLMAO!

For optimum audio quality, the Mithril caps need terminals made from
unobtanium, or at least expensivium. Jim's (hopefully patented) rolling
pin technique is great for removing oxygen from PCBs, but the rolling
pin must likewise be unobtanium.

Cheers
Frodo

Winfield Hill · Jan 9, 2005

Jim Thompson wrote...

Winfield Hill wrote:
On Fri, 31 Dec 2004 Jim Thompson wrote...
Winfield Hill wrote:
Jim Thompson wrote...
Winfield Hill wrote:
Winfield Hill wrote:
[snip]

OK, I've gotten my computer running again, wheew! and will try to
find the time to evaluate these six interesting 2n7000 spice models.

Thanks, Win, I appreciate the help... if there's anyone here with
"hands-on" you're "the-man" ;-)

Sheesh, Jim says such nice things about me, almost a week goes by,
and I'm only now sitting down to take a better look at the issue.

--
Thanks,
- Win

Jim Thompson · Jan 9, 2005

On 9 Jan 2005 15:04:02 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Winfield Hill wrote:
On Fri, 31 Dec 2004 Jim Thompson wrote...
Winfield Hill wrote:
Jim Thompson wrote...
Winfield Hill wrote:
Winfield Hill wrote:
[snip]

OK, I've gotten my computer running again, wheew! and will try to
find the time to evaluate these six interesting 2n7000 spice models.

Thanks, Win, I appreciate the help... if there's anyone here with
"hands-on" you're "the-man" ;-)

Sheesh, Jim says such nice things about me, almost a week goes by,
and I'm only now sitting down to take a better look at the issue.

480)460-2350 | |
| E-mail Address at Website Fax

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