Finding Specific part in BOM from vague description


#1

Oh no, another new project.

I’m looking at RusEFI, and they supply a BOM. But the diodes are generically labelled rather than a specific part#. Is there a way to actually figure out what they are, because there is 370 of them at element14.

This is the new iBOM(interactive BOM) of it, and if you go to # 21, 22, 23 it’s says: diode SIL-2, diode SOD-123, and double Schottky sot23.
https://rusefi.com/docs/ibom/frankenstein_latest.html

I looked up double Schottky sot23 on element14, but there are 370 of them so I don’t know which one will do.
https://au.element14.com/w/c/semiconductors-discretes/diodes/schottky-diodes/prl/results?diode-case-style=sot-23&st=SCHOTTKY

Is there any way to work it out.

EDIT - There a SCH pdf, if it helps.
https://svn.code.sf.net/p/rusefi/code/trunk/hardware/frankenstein/


#2

Your last one takes the prize: in

bom_dictionary_sp.csv

we find:

sot23_DOUBLE_SCHOTTKY,BAS70-04FILM,497-2516-1-ND,input protection diode

The 497-2516-1-ND number is a digikey product code which pulls up the diode they want. There is also a forum there where you can ask if all else fails (it looks like this is a common topic although I didn’t see the diode question particularly).

Peter


#3

Damn, I’ve been going through all the Digi and Mouse for days, but didn’t think to look in that one.

Back to the old grindstone.

Thanks


#4

OK, I found a SOD-123_DIODE on another board from the same group and it had a part# BAT54T1GOSCT-ND, so I think I’m ok there.

Now I’m still missing the SIL-2_DIODE. On page #2 of the SCH pdf there is something called snubber diodes in the very top right corner with the 12off D401-D412. Are snubber diodes anything in particular, like something I can look up in Digi, ie silicon rectifier, zener, etc.


On the other Frankenso board in SCH pdf - page 1, top right, connected to a net called 12V-SNUB - there are diodes on the connector to the INJ channels, like the other. But when I look up D12-D23 in the frankenso.csv BOM there is no entry.
https://rusefi.com/forum/viewtopic.php?f=4&t=569

I probably don’t need them, but it’s best to get them now in a bundle because if I need them latter they will hit me with postage.


#5

Snubber diodes are usually fast recovery, they are to deal with the back emf from an inductive load when it turns off (I expect the injectors may be an inductive load). It sort of looks to me like they are optional, but it isn’t clear. Can’t you ask them in their forums? That would probably be safest.

Peter


#6

Unfortunately the forum isn’t very nice.

Yeah INJs are a coil, so it should have back emf - is that flyback -

Fast recovery 12V, might try that in a Digi-key lookup.


#7

You probably want high voltage, as the inductive kick can be hundreds of volts and usually they are fairly high current too as the inrush current can be quite large (depending on the size of the inductor) , although the holes look set for small signal type diodes and through hole and didn’t seem to be populated in one of the pictures of the board, which is why I think they may be optional (along with the ignore designation in the BOM cvs). Unfortunatly not much about that is very clear :slight_smile: .

Peter


#8

Looks like it was originally a Schottky, but they switched to a std 4007 because it’s wasn’t that fast. Latter on they talk about a TVS, but they didn’t come to a conclusion on which one to use.

Looking at a parametric of TVS on element14 I’m down to 900 listings. I know the pads are THT 2.54mm apart, but in frankenso iBOM the pad is 0805 for the similar diodes. I think it can do either.

I’m not sure what specs I am looking for, and I know it takes a lot of volts - maybe 130V? -, but don’t I want a clamping of 12V max. I don’t know what breakdown voltages are so I don’t know about them.
https://au.element14.com/w/c/circuit-protection/tvs-transient-voltage-suppressors/tvs-diodes?no-of-pins=2pins&packaging=each&range=inc-in-stock


#9

Breakdown is the one you want to worry about. If it sees more volts than that it’s unhappy. Bigger is better in this case, I’d do a couple of hundred volts anyway.

Peter