Which N Or P Power MOSFETs ?

Put more in parallel, or use electrostatic speakers.

Cheers

Phil "Bigger hammer" Hobbs

Buy ear buds.

John "Leave me alone" Larkin

Ooh, fancy. In the USA, we call them "parts."

Elements are things like copper and radium.

We have a person down the hill from us, teaching himself to play trumpet at night. Luckily, it's a ways down the hill.

We never believed the SOAR curves, so we just pushed them until they exploded. We found a nice pair, n and p channel.

This makes 17 kilowatts peak, for NMR and MRI microimaging. We measure distortion in parts-per-million.

The firmware runs a realtime simulation of fet die temperature to manage shutdown. That optimizes expensive silicon better than some simple current limit.

Right, there's a reason they use big honkin' celled MOSFETs rated for 50 amps pulsed to push only 5 amps at 20 Hz as half of a complimentary source follower in a linear amp. Rds on doesn't increase with temperature across the whole operating regime, at low Vgs the cells current-hog. A source-follower operates at low Vgs. The fine print assumption with the SOA curves tells you "don't do that"

Even calculating on paper whether a FET used for a PWM switching application will always be within its SOA where it's assumed it will either be fully off or be in the equivalent of a BJTs saturation, with a relatively constant low Rds_on, is kind of a pain in the rear chicken-or-egg-problem with the info the datasheets give you, going back and forth between the SOA and the temperature de-rating info.

The case will not be at 25 degrees C like the curve is plotted at. What it is depends on what its Rds on is. But the Rds on depends on what the case temperature is. Etc. Somewhere there was an article about a systematic method for solving this problem but it's also kinda what LTSpice was invented for.

If you go to buy even the antique IRF510 from IR off the shelf in 2020 the datasheet says like "The IRF510 using IR's patented 3rd generation HexTrenchWell technology offers improved...."

they're not the same part.

Excuuuse me! _You're_ the one who's been complaining that a 17 amp Class D audio amplifier isn't powerful enough. ;)

Cheers

Phil Hobbs

(Who listens to music about twice a month at most, apart from church)

r for 1kW amps fine.

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Your dialect is a little impoverished.

lists fifteen different definitions for the word "element" in different con texts.

The first is "a component or constituent of a whole or one of the parts int o which a whole may be resolved by analysis" which clearly includes chemica l elements , but does make room for other uses.

Phil Allison is wrong. You can talk about the elements you use to assemble into a loudspeaker. "Components" is the word you use when you have to go ou t and buy them, but "elements" works better if you are analysing their effe cts on the sound that comes out.

Only for John Larkin - he can't design stuff by intention, because he hasn' t got a clue what he intends to design, or why. He's got customers for tha t.

======

near

That probably means that John Larkin never understood what the Safe Operati ng Area curves were trying to tell him. They do present a plot of safe dra in currents against drain-to-source voltage which does tell you something a bout operating the parts outside the saturation region, despite Bitrex's cl aim to the contrary,

The data sheet for Phil Allison's favourite N-channel part

shows just such a curve at figure 8.

shows a very similar datasheet for the P-channel part Phil reccommends. Aga in, the SOA curve is a figure 8.

It's pretending to be an alternator. It's actually very quiet, running full blast.

I'm one of the few people, along with Horatio Hornblower, who dislikes music.

============================

The f****it OP posted this complete drivel:

" These days, are they really making full range (20 Hz .. 20 kHz) speaker elements that can handle 1 kW power levels ? If not, what is the point of making kW class full range amplifiers ? "

Go ahead.... make my day.

...... Phil

====

cater for 1kW amps fine.

=============

contexts.

s.

The issue was a linguistic one, which you don't seem to want to think about .

In a particular context.

ound that comes out.

That's what I was saying.

akes technical sense ?

There are people who are devoted to the idea of using a single driver to co ver the entire audio spectrum - from 20Hz to 20kHz. I've seen a write-up of a huge full range electrostatic speaker that was intended to do just that. Not having to worry about cross-overs is an advantage of this approach, bu t not a compelling one

Nobody sane seems to bother, and the only bit of the audio range that needs kilowatt power is the low frequency end, so why bother making a high power amplifier that can handle any frequency higher than a couple of hundred Hz ?

Enjoy.

Bill Sloman wrote: ===============

---------------------------------------------------------------------------

This common BJT has a limit at 100V of 2A - but for 1 second. Big difference.

This " lateral mosfet " is rated for 4A and 100V for 10ms and 1.25A for 1 second.

FYI:

In actual use and abuse, the last example has proven to be the least likely to fail. Mainly because of an un-speced parameter:

The gate forward voltage rises with chip temp, so a 12V zener clamp on the gate prevents failure. Max available current falls to 2 or 3A, the chip reaches 170C and there is no further temp rise.

I have seen products using these mosfets where the cooling fan failed, the amp lost most of its power but nothing more.

More impressively, one product (made by UK firm H-H ) where the mounting bolts *all* worked loose after thousands of thermal cycles, the devices were all floating loose yet not a single failure seen.

Gotta love that.

...... Phil

Bill Sloman is Besoted with his own bullshit.

=====================================

Rest of Bill's meaningless opinion sprouting deleted.

To spare gentle readers the pain.

..... Phil

The one you were in. Upside-down-under was being a bit more analytic.

Phil in his Flyguy emulation mode, where he snips anything he can't understand.

Bill Sloman is Besoted with his own bullshit. ==================================

FYI to all,

I actually re-posted the absurd question - with a challenge that Bill try to explain it.

However, just like the narcissistic fake & coward Bill has always been

- he dishonesty avoided it.

Wot a puke.

..... Phil

On Sunday, November 22, 2020 at 4:03:10 PM UTC+11, snipped-for-privacy@gmail.com wrote :

==========

to explain it.

When I checked out my response via Goggle groups I found this

"> " These days, are they really making full range (20 Hz .. 20 kHz)

akes technical sense ?

There are people who are devoted to the idea of using a single driver to co ver the entire audio spectrum - from 20Hz to 20kHz. I've seen a write-up of a huge full range electrostatic speaker that was intended to do just that. Not having to worry about cross-overs is an advantage of this approach, bu t not a compelling one

Nobody sane seems to bother, and the only bit of the audio range that needs kilowatt power is the low frequency end, so why bother making a high power amplifier that can handle any frequency higher than a couple of hundred Hz ? "

It strikes me as clear and coherent response - but then again it would. Cle arly it wasn't what Phil wanted or expected, but I don't think he can reaso nably claim that I avoided it.

Then again, Phil isn't known for his reasonableness. My guess is that he st opped reading at the first line in my response and got distracted before he 'd actually read on to get to my response to his challenge.

These have comparatively small die size for a TO-247. Probably better parts for linear audio out there I am thinking. But that's just by going on the spec sheet. YMMV

If for switching, there is definitely better parts that these at 200V.

Not sure how good Exicon Lateral MOSFETS but supposedly they are great for class AB or maybe even class A audio amps.

With a good component power sharing technique, (whichever technique that might be), lots of available FETs should work if you have enough of them.

==========

Probably best used as " current dumpers " to eliminate the issue altogether.

..... Phil