schottky tempco

Not really. In fact I seem to remember discussion about the tempco reversing at certain (usefully low) current levels. This would happen by an effective positive tempco in series with a negative semiconductor tempco, combined with the nonlinear behavior of that semiconductor.

Lemme see here... Popular, relatively small schottky 1N5817L

(Middle left page 2.) The graph shows two curves, the hotter curve consistently less than the cooler curve. Nope, that's no good... how about something with a little more juice? (Same place.) Hmm nope, still negative tempco...

Might Google for the discussion. It was last yearish...

Tim

--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

"kell"  wrote in message 
news:1148908508.542829.155820@g10g2000cwb.googlegroups.com...
> Do schottkys have the same temperature coefficient as other silicon
> diodes?  Many thanks.
>

Looking at the second of the datasheets you linked to, it looks like the schottky tempco starts around -1.6mV/C and gets to around -1mV/C at higher currents.

Here's a datasheet I pulled up more or less at random that shows a rectifier with a tempco that eventually goes positive as the forward current increases past a certain point

(see diagram 8), but it's not a schottky. Maybe the discussion you remembered wasn't about schottkys... I did a desultory search but didn't come up with anything.

"kell"

** You should not use the term " tempco " loosely and wrongly like this.

Diode "tempco" of a diode is simply the incremental change in conduction voltage per degree C of ambient temp change.

What YOU are looking for is called the "Forward Voltage Drop Characteristic" as seen on the data sheet YOU quoted.

...... Phil

Well yes, if you want to be exceedingly stringent about it.

For example, in citing Vf at 3 amps in Figure 3 of

I use deltaVf/deltaT over an interval of 100 degrees C as a stand-in for dVf/dT. And even according to elementary calculus, there has to exist some temperature between 25 degrees and 100 degrees where dVf/dT equals deltaV/deltaT over the interval of 25 to 100 degrees, assuming Vf as a function of C (and the first derivative) exhibit(s) no discontinuity, you know the drill.

"kell"

** No, my smartarse over snipping, context shifting friend, YOU are plain wrong.

You simply asked: " Do schottkys have the same temperature coefficient as other silicon diodes? "

It was the wrong question.

........ Phil

Schottkies tend to have somewhat lower junction tc's than pn diodes. There are a lot of schottky chemistries around, so they vary.

Any semiconductor diode acts like an ideal semiconductor in series with some bulk resistance, and that bulk r tends to have a positive tempco. So most real diodes have negative tc's at low currents and positive tc's at very high currents, with a zero tc point somewhere between, sometimes but not always at sane currents. I posted a graph of a small-signal schottky to a.b.s.e., and it has a zero tc point around 15 mA.

John

Yup, zero tempco at about 15 amps. Nice.

Ignore Phil; he has a disorder.

John

I am rather sensitive and on the lookout for anyone with any headers from Australia claiming so severely that someone is "plain wrong" by arguing on finer points. And I note in addition a bit of characteristic spelling issues that appear to me more specific to a somewhat famous sub-troll than to a nationality. This makes me wonder if you are the major Australian sub-troll that got his own FAQ!

- Don Klipstein ( snipped-for-privacy@misty.com)

"Don Klipstein"

** ROTFL !!!!

Klipstein is a completely pompous ass !

** Take that up with Microsoft.

I use the MS Word "spellchecker" like most OE users.

....... Phil

And I know how spellcheckers allow misspellings and less-common spellings that are outside their dictionaries and/or are deliberate.

I hope you can quickly better distinguish yourself from the bigtime famous/infamous Australian sub-troll better than implementing a few words with low usage count in the megareams of garbage already spewed by that sub-troll but sounding slightly more-often-used by oldtimers and Britons in the sci.electronics newsgroups!

Are you currently capable of denying that you are the famous/infamous sub-troll widely mentioned to be from Australia and so bad a sub-troll as to get his own FAQ? If you can, can you also deny being among the probably part-per-billion-range fraction of this planet's population that is insane enough to be in any way a fan of that major offender?

- Don Klipstein ( snipped-for-privacy@misty.com)

"Don Klipstein" <

( snip reams of TRIPE )

** Piss off - you ASD f***ed half wit.

........ Phil

John Larkin wrote: I posted a graph

Thanks. Unfortunately, I'm a Google groupie. No a.b.s.e. for me!

It was an HSMS2810, originally an HP part. Most small-signal schottkies look similar.

John