Ultra-low forward voltage Schottky-rectifier

[MRupp]

Read the first post carefully and try again

I must admit that I usually fly over most (though not all) posts, including yours.

Having said that, if I look at the datasheets that I have at hand and compare diodes of the same rating (ok, my shottky’s are dual devices) the shottkys have invariably a much lower forward voltage drop than the standard diodes.

Example Ixys DSEP 15-03A (15 A, 300 V) VF _ IF = 15 A: TVJ = 150°C 1.21V, TVJ = 25°C 1.68 V

IR 16CTQ100 (16Amp, 100V) VFM Max. Forward Voltage Drop 0.72 V @ 8A (Per Leg) at TJ = 25 °C 0.58 V @ 8A (0.69 V @ 16A) TJ = 125 °C

The datasheets have diagrams with the related curves, and it becomes even more apparent. Same with other packages / higher current ratings, e.g. IR 40CPQ100 against various 30A diodes.

[h_a]

Thanks for the reference to the IR-schottky!

I'm not a diode guru, I have to admit that I randomly picked a cheap Schottky diode with comparable ratings from the Digikey-catalogue and it didn't perform that well.

So the IR 16CTQ100 is 0.72 V at 25°C at 8 A (you state 0.58 V). For identical conditions the V30100S is about 0.52 V.

Ok that's not that much.

The really nice thing is the price! Your IR 16CTQ100 costs at Digikey 1.93 Euro in the uninsulated TO-220 package, the VF30100S goes for 1.17 Euro in the insulated TO-220 package.

It's not exactly half the price, but good value for the money for sure. There are even standard Silcon-bridges that cost more than 4 of these.

Have fun, Hannes

[MRupp]

(you state 0.58 V)

Read the first post carefully and try again

OK, omitted the comma after 25 °C - thanks for spotting

On prices, Ebay is your frind; I found all my diodes (IXYS FREDs, IR Shottky's) at Ebay well below EUR 1 per piece, often still in the original tubes, and even the same types that boutique component suppliers (Thel in Germany) sell for an arm and a leg. Lastly, I suggest to use PSUDII to model your power supply to get the max current peaks, and if low forward voltage drop is your primary goal, run them hot (but not too hot).

[lineup]

Schottkys are the best when you are after low drop.
No question about this

The only hookup with schottkys is that they often come for a bit lower voltages.
But if your power supplies are not too high voltage, then it is a good option to get lowest power losses.
I do not know the current developement in power Schottky.
But I wouldn't be surprised if there are now higher voltage devices, too.

Now there is, of course, an easy way to compensate: One extra winding in your transformer secondary .....


Best Regards to Dannemark, Dannebrogen och Hannes
You are quite alright by me, man!
The old school very, very Gentle Man of Svea Rike = Sve-rige = Sweden
Lineup

[h_a]

run them hot (but not too hot).

Hey, run them hot to reduce power dissipation

OK, omitted the comma after 25 °C - thanks for spotting

It's a pleasure - especially because that was not intended! I simply edited too much - and forgot that line accidentially

@liney: thanks!! I'm not danske, but nevermind. And of course all the best to you, Hannes

[MRupp]

Hey, run them hot to reduce power dissipation

Exactly, if you want get low voltage drop, that is, and btw. I don't think you will save anything worthwhile mentioning, at least not in a normal amp: a lower rated/smaller device and just enough cooling, if any - you need to calculate the correct current values and dissipation, off course.

[h_a]

Martin, don't worry, I perfectly understood! It's obvious from the datasheet. I was just joking

Have fun, Hannes

[jan.didden]

How about this 'ideal diode' ?

Jan Didden

[h_a]

Hi Jan, thanks for the article!

Amazing what things exist! Might be interesting for low-power gear! Just a pity that most discrete line-level gear exceeds its 26.5 V voltage rating.

Do not fear smd, Hannes

[jan.didden]

Originally posted by h_a
Hi Jan, thanks for the article!

Amazing what things exist! Might be interesting for low-power gear! Just a pity that most discrete line-level gear exceeds its 26.5 V voltage rating.

Do not fear smd, Hannes

Presumably you can use them floating at any voltage by lifting the gnd lead with a zener or something like that.
Imagine, a 5A diode with 25mV loss only!

Jan Didden