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Author Topic: Schottky Diode Help  (Read 10845 times)

rukiddingme

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Schottky Diode Help
« on: March 22, 2010, 09:35:15 PM »
Hi all,

wikipedia article on Schottky diodes states:

A normal diode has between 0.7-1.7 volt drops, while a Schottky diode voltage drop is between approximately 0.15-0.45 volts. This lower voltage drop can provide higher switching speed and better system efficiency.

I have looked everywhere to find Schottky diode with a voltage drop of .15-.45, but I can't find any anywhere.

Can I ask if anyone knows where one can get Schottky diodes with a .15 voltage drop?

Thanks in advance.


kooler

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Re: Schottky Diode Help
« Reply #1 on: March 22, 2010, 11:02:38 PM »
hello
the bat 46 and the rk44 will do what you want
the bat46 is a 100 volt diode and the rk44 is a 40 volt
the 0.25 FV on the datasheet is the max use
here is a place that has the almost rare bat46

http://www.angelfire.com/electronic2/index1/bat46.html
 
and the rk44
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16730

hope this helps

robbie

gyulasun

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Re: Schottky Diode Help
« Reply #2 on: March 22, 2010, 11:59:24 PM »
@rukidding

At what current level do you want .15V voltage drop?

rukiddingme

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Re: Schottky Diode Help
« Reply #3 on: March 23, 2010, 01:04:37 AM »
@rukidding

At what current level do you want .15V voltage drop?


It's a guess, but an amp give or take a half amp.

rukiddingme

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Re: Schottky Diode Help
« Reply #4 on: March 23, 2010, 01:16:56 AM »
hello
the bat 46 and the rk44 will do what you want
the bat46 is a 100 volt diode and the rk44 is a 40 volt
the 0.25 FV on the datasheet is the max use
here is a place that has the almost rare bat46

http://www.angelfire.com/electronic2/index1/bat46.html
 
and the rk44
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16730

hope this helps

robbie


Yep, the RK44 looks like exactly what I want. I'm at 10 -15 volts so I don't need 100 volts. Where did you see the forward drop spec for the RK44?

rukiddingme

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Re: Schottky Diode Help
« Reply #5 on: March 23, 2010, 01:25:25 AM »
I'm gonna piggy back some more questions on this thread.

I have seen many people bundle multiple diodes in parallel. I am under the impression that this does not decrease the forward voltage drop, but does give the bundle the ability carry a higher current. Is this the correct situation with a diode bundle?

Is there any down side to creating bundles of diodes for a full wave bridge.

Is there no benefit of a diode bundle if a single diode is rated for the voltage and current?

Is there any benefit to using diodes very close to the actual voltage and current of the circuit, or is any diode above the volts and current just as good?



kooler

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Re: Schottky Diode Help
« Reply #6 on: March 23, 2010, 02:38:16 AM »

Yep, the RK44 looks like exactly what I want. I'm at 10 -15 volts so I don't need 100 volts. Where did you see the forward drop spec for the RK44?

http://www.datasheetarchive.com/pdf-datasheets/Datasheets-29/DSA-574476.pdf

look at the second chart on the first row.. it shows the forward volts at the needed forward current

robbie

rukiddingme

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Re: Schottky Diode Help
« Reply #7 on: March 23, 2010, 05:09:10 AM »
http://www.datasheetarchive.com/pdf-datasheets/Datasheets-29/DSA-574476.pdf

look at the second chart on the first row.. it shows the forward volts at the needed forward current

robbie


Am I reading the data sheet right to say, maximum volts 30, voltage loss at 1-3 amps is .55?

Do I have to worry about a minimum voltage and what would that be?

blueplanet

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Re: Schottky Diode Help
« Reply #8 on: March 23, 2010, 04:05:30 PM »
You need a germanium schottky, not a silicon schottky.

mscoffman

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Re: Schottky Diode Help
« Reply #9 on: March 23, 2010, 04:57:47 PM »

Am I reading the data sheet right to say, maximum volts 30, voltage loss at 1-3 amps is .55?

Do I have to worry about a minimum voltage and what would that be?

Using kooler's (above) data sheet.

Look at: VF—IF Characteristics (Typical) chart.
(forward voltage vs. forward current)

At the forward voltage of .2Vdc you should be able to draw
(only) 200ma through the diode, even into a short circuit.
The higher the forward voltage the more current can be
drawn. If your load has a characteristic impedance different
from zero  :)  then the amount will be less. The .55 drop
is the worst case for any valid voltage and current and for
any operational diode. This is a real component, so you
have to leave the "perfect" operational models behind
and use the charts.

:S:MarkSCoffman


rukiddingme

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Re: Schottky Diode Help
« Reply #10 on: March 23, 2010, 09:31:41 PM »
Cool, so the either the RK44 or the bat 46 would be appropriate for a system running at 9 volts and .8 amp.

Is there any advantage from using bundles of diodes of will just one diode be better?

If this is correct, thanks all.  :-)

kooler

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Re: Schottky Diode Help
« Reply #11 on: March 24, 2010, 06:05:21 AM »
hy
the rk44 has big leads on them so they won't fit in a solderless board 3amp diode..
(breadboard)
just thought i tell you before you bought them..

robbie

rukiddingme

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Re: Schottky Diode Help
« Reply #12 on: March 24, 2010, 06:20:57 AM »
hy
the rk44 has big leads on them so they won't fit in a solderless board 3amp diode..
(breadboard)
just thought i tell you before you bought them..

robbie

No worries, I'm going to bundle them and make a full wave bridge, so it'll be a permanent thing. tks

jadaro2600

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Re: Schottky Diode Help
« Reply #13 on: March 25, 2010, 04:02:37 AM »
Having several low voltage drop diodes will boost your forward current capabilities, but if one of them fails the reverse voltage, then all of them becomes useless to suppress the one which failed.

Such a low drop of voltage is usually indicative of a low reverse voltage as well, just a reminder.

rukiddingme

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Re: Schottky Diode Help
« Reply #14 on: March 25, 2010, 06:09:19 AM »
Having several low voltage drop diodes will boost your forward current capabilities, but if one of them fails the reverse voltage, then all of them becomes useless to suppress the one which failed.

Such a low drop of voltage is usually indicative of a low reverse voltage as well, just a reminder.

I'll check them all before I install them.

What would cause a diode to fail in a full wave bridge?