There is a diode for BAT54A. But its supply current do not suit into my application. BAT54C is what I want. Schema symbol and PCB footprints are same, only name changes. What are all the places I need to go to make the replacement?
If there already is a BAT54C part somewhere, then where is it?
Both are 3 bit level shifters if you want to know.
Be careful! In real components, BAT54 numbering may be tricky and depend upon vendor. I think that BAT54 is a single diode in SOT23 while BAT54C is a dual common cathode in SOT23. But there are variants (I hate that word) in SOD123 and SOT323 and other packages, so beware of vendor and full part number. See https://www.vishay.com/docs/85508/bat54.pdf as one example.
How much current do you want? Use a completely different device if you want current > 100 mA or so.
BAT54 series are all schottky diodes and forward voltage will be significantly less than that for a small PN junction diode at similar current.
Nahh,
You originally posted while I was searching for BAT52 (should be BAT54) so I could understand what the OP was writing about.
I then read your reply and decided to contribute with a comment and link.
Meantime you posted the same link as an edit
From the fist page of the linked Vishay datasheet (In case it disappears in the future):
No suffix = Single.
A = Common Anode.
C = Common Cathode.
S = Series connection.
BAT52 != BAT54 but I have not compared datasheets.
And you always have to be extremely careful with any part in a SOT-23 package. The trouble here is that manufacturers do not agree where pin number 1 is on this package. The numbering shown above is the most common, but you can’t rely on that.
You can put both diodes in parallel to push a bit more current through a SOT-23, but it’s a small package and limited by dissipation, so a diode in that package is never going to conduct much current for long. some MOSfets in SOT-23 do 3A or even 5A, but those have a very low Rds-on and therefore low dissipation.
First: For me there are no such term as diode supply current.
Second: Forward current for BAT54A and BAT54C are the same.
Pin numbering is not important. Important is that all BAT54(A/B/C) from all manufacturers have the same configuration - you can replace one with another (however manufacturer numbered pins in his datasheet).
That’s fine if you only have fully specified parts, but when you use a generic diode as a schematic symbol and assign a SOT23 footprint for the BAT54xx, then things can get mixed up.
For example, this is a generic footprint in KiCad For SOT-23:
But for this part it is apparently indeed relatively safe. All the BAT54xx variants appear to be default KiCad symbols with Footprints already assigned. I have not verified them, but KiCad’s default libraries tend to be pretty reliable.
I have a simple answer to this conundrum (inconsistent pin numbering of SOT23)! Replace pin numbers with:
“The pin that is on the lower left when the view is rotated so that the single pin side appears on top” etc. Then put this into a small font so that it can fit nicely onto the diode symbol.
A very old PCB program I used long ago (Ultiboard in the DOS age) had no SOT-23 packages with pin numbers. It only had SOT-23 packages with pin names such as “E”, “B”, “C” for BJT’s and or “G”, “S”, “D” for Fet’s.
It was a creative solution that was both simple and usable.
Just have a look at some of KiCad’s default symbols:
The long string is “Gate”, “Source”, “Drain” for a dual fet in probably a SOT-23-6 package. and the "GSD for the two transistors are in order of pin numbering, just as the “GDS” and “BCE” suffixes for the other two transistors.