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Panasonic schottky or not ?

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legg
Guest

Mon Dec 18, 2017 6:52 pm   



In the Panasonic schottky diode catalog, there are a number of parts
that don't state that the parts are schottky, though the top of the
catalog page still carries the schottky barrier diode heading. They
share similar part numbering structures and descriptions as parts in
the ultrafast rectifier line.

Schottky parts are fabbed using the same 'planar' process, but the
'epitaxial' description seems out of place here.

A possible confusion is aggravated by Panasonic's tendency to describe
the reverse recovery time of schottky parts, when positioned in the
standard Trr test circuit, where performance is basically an RC
effect.

eg:

https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf

Does anyone out there have actual experience in weeding out small
signal and rectifier schottkys from UFRs in the Panasonic line-up?

I've only ever used a few of their schottky parts. Conventional fast
diodes are easily supplied by more prominent mfrs, so there's never
been an issue. Vendors seem only to have the same ambiguous data
sheets to draw from. They appear to have no trouble correcting
Panasonic's faulty package drawing designations - but descriptions of
'schottky or not' follows the data sheet page catalog section's
header.

RL

Jon Elson
Guest

Mon Dec 18, 2017 10:05 pm   



legg wrote:

https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf
Quote:

Does anyone out there have actual experience in weeding out small
signal and rectifier schottkys from UFRs in the Panasonic line-up?

Well, just look at the forward voltage drop, and you should be able to
easily separate Schottky from P-N junction diodes.

Jon


Guest

Tue Dec 19, 2017 9:21 pm   



On Mon, 18 Dec 2017 11:52:44 -0500, legg <legg_at_nospam.magma.ca> wrote:

Quote:
In the Panasonic schottky diode catalog, there are a number of parts
that don't state that the parts are schottky, though the top of the
catalog page still carries the schottky barrier diode heading. They
share similar part numbering structures and descriptions as parts in
the ultrafast rectifier line.

Schottky parts are fabbed using the same 'planar' process, but the
'epitaxial' description seems out of place here.

A possible confusion is aggravated by Panasonic's tendency to describe
the reverse recovery time of schottky parts, when positioned in the
standard Trr test circuit, where performance is basically an RC
effect.

eg:

https://media.digikey.com/pdf/Data%20Sheets/Panasonic%20Electronic%20Components/MA3J744.pdf

Does anyone out there have actual experience in weeding out small
signal and rectifier schottkys from UFRs in the Panasonic line-up?

I've only ever used a few of their schottky parts. Conventional fast
diodes are easily supplied by more prominent mfrs, so there's never
been an issue. Vendors seem only to have the same ambiguous data
sheets to draw from. They appear to have no trouble correcting
Panasonic's faulty package drawing designations - but descriptions of
'schottky or not' follows the data sheet page catalog section's
header.

RL


I was looking on ebay at some 6 Amp diodes. There seems to be hundreds
of them being sold on ebay, and sold as rectifiers. I dont do much
design work, just some repairs, so I have not run across this till now.
I just thought a diode is a diode as far as those being sold for
rectifiers. And that generally refers to diodes rated at 1A or more.

My intended use at the moment is for a diode to use on a piece of
machinery and used to prevent 12 volts DC from back feeding in an
alternator charging circuit. One part number that I thought might fit my
needs for voltage and amperage was Schottky diode 1N5817. (Which was too
light duty for my needs). There are also a whole bunch of diodes being
sold for "Solar panel" use, with numbers such as 6A10 (6 amp) or 10A10
(10 amp). There seems to be a ton of them listed on ebay. However both
these 6A10 and 10A10, as well as 1N5817 are ALL listed as Schottky. Yet
over half of the listings on ebay DO NOT contain that word.

This made me question the suitability of this type of diode for my
application. I ended up reading up on the schottky diodes, to learn what
makes them different from common diodes. I learned their
characteristics, but was left not knowing if they would suit my needs in
this charging circuit or not. My guess is that they probably would work
just fine, but I'm no expert on circuit design, and dont take chances on
something like this, where a costly alternator or the gas engine itself
could be damaged by using the wrong diode. I ended up buying a different
numbered common diode for this use.

But what gets me, is that close to half the ebay listings do not even
use the word "schottky" in their listings. So what would happen if I was
building a power supply and used schottky diodes where common diodes
were intended? Once again, it looks like they would probably work, but
"probably" is not good enough for me. So, selling these without using
that word, should not be allowed.

It appears that schottky diodes are probably superior to common silicon
diodes, but are they directly interchangable? I dont know????

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