Substitute Lateral Mosfets

hello,
this might be some stupid question so thanks for listening ;-)
i´m about to start some mosfet amplifier project and already look for parts and designs.
the 2sk1058/2sj162 combination is often seen and known to be good and reliable.
these are lateral mosfets but how do i know with which devices i can substitute them.
i was thinking about 2sk1530/2sj201 cause of the lower price.
in anthony holtons design "lateral mosfet amplifier" he notes you can exchange 2sk2221/2sj352 with sk1058/2sj162 but in no case with for example irf240/irf9240 (which would even blow them up).
so what do i have to look for?

TIA
Jens
 
There are two UK companies manufacturing equivalents for
the Hitachi devices, Semelab and Exicon. The Semelab ones
seem to be about the same price as the Hitachi devices, but
it seems Exicon are quite a bit cheaper. Have a look at the
following link. Unless I misunderstood something, there is
no minimum order and no extra cost for shipping etc.

http://www.profusionplc.com/hitachi.htm

Otherwise, Sloane uses the SJ162/SK1058 in all his MOSFET
amplifiers, and he mentions that IRF640/IRF9640 can be used
as a replacement in som of his designs, without furhter details
on which ones, or under what conditions. If memory doesn't
fail me, someone made a claim in another thread recently that
only lateral MOSFETs have a negative temperature coefficient, so
replacement with non-lateral devices without adding some
temp. correction/protection circuitry may not be so wise.
 
"only lateral MOSFETs have a negative temperature coefficient, so
replacement with non-lateral devices without adding some
temp. correction/protection circuitry may not be so wise."

Yes. Non-lateral MosFets are more fragile, and exhibit positive temp co at usual current in audio amps. Another problem is higher transconductance, which can cause HF oscillations under some circumstances.

Regards, Pierre Lacombe.
 

UrSv

Member
2002-01-31 5:48 pm
Sweden
It's in my profile now...I am on both sides of Germany. ;O)

Building far too few amps but starting to pick up speed. The pairs were for a set of A75 but I never got the hang of if they would be OK or not and now I am building a P1.7 and some A30/60s (decision not made - part gathering going on).

/UrSv
 
I think the sk1530/2sj201 are discontinued. At least Hitachi
seem not to produce them anymore. There is nothing wrong
in using them, of course, if still available, but it may be wise
to buy a few extra, just in case.

Since they are discontinued, Hitachi didn't provice any
datasheets. how do they compare to SJ162/SK1058, and
why would they be preferred?
 

UrSv

Member
2002-01-31 5:48 pm
Sweden
As far as I know they are not Hitachis but Toshibas and I think they are still in production. At least Elfa in Sweden, Schuro in Germany still list them...

Go to http://www.elfa.se/ and enter 2SJ201 in the upper left search window. You will get a list of 2SJ201 and 2SK1530 when selecting the hit. The little blue button with the i on it will give you the respective datasheet.

/UrSv
 
You are quite right UrSv. I admit being a bit embarrased to
miss that, since Elfa is my local supplier. :) You are also
right that these are Toshiba devices according to the datasheets.
However, searching for these part numbers at Toshiba does
not give any hits, whatever that means. BTW are you sure these
are also lateral devices, since the datasheets do not say
anything about that?
 

UrSv

Member
2002-01-31 5:48 pm
Sweden
UrSv,

Yes, those links worked better. I searched the main japanese
site, and didn't find them there. Incidentally, the datasheet links
do not work on the american site, but I got them from Elfa
anyway.

I think SJ301/SK1530 are not lateral MOSFETs. I assumed them
to be from the original post in this thread, but maybe I
misunderstood Jens. This is also why I assumed them to be
Hitachi devices, since I think only Hitachi makes lateral MOSFET
(apart from the british second sources).

The temperature behaviour of SJ201/SK1530 does not look
very promising as a replacement for lateral MOSFETs, but I
am no expert on MOSFETs, so I leave that to others to judge.

I still do not understand Jens' claim that they are cheaper
than SJ162/SK1058, at least it is the other way around here
in Sweden. Or maybe he assumed paralleling the latter devices
to handle the same power?
 
christer,
at first i just couldn´t get the 2sk1058/2sj162 from a cheap and near distributor so the 2sk1530/2sj201 were effectively cheaper for me. but then i saw them at www.reichelt.de for same price as the 2sk1530... at www.nedis.com.
that the latter devices have positive temperature coefficient
was almost reason for me not to build the crescendoME
but the PCB includes protection for everything, dc-servo, bias
so i don´t have to worry.
about dicontinueing the devices...
i don´t think so but i might be wrong.
you guys make me real nervous about getting more.

:bawling:
money´s gone (loads of watts cost loads of bucks)

greetings
jens
 
Jens,

Don't worry. I misunderstood your original post and believed
that SJ201/SK1530 were also lateral MOSFETs and so belonged
to the set of discontinued devices, since Hitachi seems only
to produce the SJ162/SK1058 and maybe some different-voltage
version of them. These are in mass production by Hitachi, and
also second sourced by two UK manufacturers.

The SJ201/SK1530 are probably non-lateral devices, primarily
intended for switching. If the particular design includes all
the necessary temp. compensation and protection and is
designed to use these devices, then it should be OK. Probably
you could use the lateral devices instead and skip the extra
circuitry, but I know nothing about that particular amplifier.
 
i really checked many companies, distributors in germany
but still if you can get the part from reichelt, just buy it there.
in 99% of the cases it´s the cheapest and one of the fastest likewise. just look at the prices for transformers.

maybe we should post all of our favourite distributors, companies so we could make up a big link list for everybody all over the planet to get best prices/services for diy´ers !?
or is it getting too commercial then?!
 
UrSv,

Do you have any particular reason to believe the Toshiba
devices were designed for audio usage? My guess is not,
since the datasheets give the usual data supplied for
switching devices, but not some of the typical data usually
supplied for devices intended for liinear usage. Furthermore,
as far as I know (which may be wrong) the only PowerMOS
devices designed for audio are the Hitachi Lateral MOSFETs,
and all other are primarily intended for switching.
A lot of amplifiers do use ordinary switching devices in the
output stage, and with proper design that probably works just
fine. My understanding is that the lateral MOSFETs primarily
makes the design much simpler and more reliable.

On the other hand, Toshiba does have a family of bipolar devices designed for power audio amplifiers, including both driver and OPS devices.
 

UrSv

Member
2002-01-31 5:48 pm
Sweden
Reason for believing they are for audio? Oh I don't know but I think it might be that:

* I have only heard it described as for audio
* The datasheet describes it as High Power Amplifier
* It does not list Rdson (AFAIK) which would be nice for switching
* It is listed as OUTPUT in the product list
* It has a complimentary (not always the case for switchers)
* It is somewhat popular in amplifiers including high-end
* It is never listed as switching which they usually are: Try:

http://www.chipdocs.com/catalog/tree.html?selid=200

They would share this with the 2SJ200/2SK1529 pair.

I am not an expert on different FET types but this is listed as pi-MOSII and not PowerMOS. I would expect most of those terms to be unique to the manufacturer (Like HEX-FET). Lateral, vertical and others I presume are construction description so that would be something else.

/UrSv