Schottky vs Silicon rectifier diode

[eem2am]

silicon vs schottky

If we think of say a Schottky like MURS360 and compare it with a 1N4007 silicon (slow) rectifier diode.

Does the "slowness" of the 1N4007 refer to the turn_on or the turn_off time ?

the datasheet of the 1N4007 doesnt seem to say about the turn_on time.

This diode is for use as reverse polarity input voltage connection for a 10 w boost smps (8-17V input, 27V output)
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1N4007 datasheet
http://www.datasheetcatalog.org/datasheet/motorola/1N4002.pdf

MURS360 datsheet
http://www.datasheetcatalog.org/datasheet2/a/0aagx5z77c2x5dr0z2iz1psia63y.pdf

 

[JStuffer]

schottky diode voltage vs current graph

Hi.
There is a little problem: MURS360 isn't a schottky diode. I'm considering that you were refering to MURS360 and not a differently named schottky.

If the important property of the diode you're using is forward recorvery, with no regards to reverse recorvery time, you may want to use 1N400x.
Look at the MURS360 diode, it has the forward recorvery about the same as reverse, between 25 and 50 ns and capacitance of 135pF at 0V. The 1N400x on the other hand has capacitance of 15pF at 4V, much less, which is - as i belive - a major factor determining forward recorvery time. I've seen a study of this forward recorvery in several diodes and 1N400x scored almost the same as the tiny 1N4148. I don't remember how schottky scored, probably very well. Just bear in mind that 1N400x is very slow in reverse, so if there's any AC signal, it may cause trouble, otherwise it's a good choice.
And make sure what diode is the fast one you're considering. Schottky or not schottky could mean a big difference.
Also note that i'm no expert and could be quite likely wrong. ;D

John

 

[frankvh]

diode schottky vs diode

From what you're saying, you don't actually care about the diode's speed. If you're using it in series with the input of your power supply to protect against reverse polarity, then that diode won't be switching - it'll always be on.

So then, the big difference between the schottky & silicon diodes, if you choose right, is forward voltage drop. Remember power P= V * I, so if your input current is significant, the power dissipation in a 0.8V silicon diode vs a 0.4V schottky could be significant. Don't take those numbers as gospel though - check the voltage vs current graph in the datasheet for each diode you're considering. There are plenty of schottky diodes out there with surprisingly high forward voltage drops.

You'll probably find the silicon diode costs considerably less than the schottky.

Frank.
https://www.frankvh.com