I’m trying identify this SMT diode to purchase a replacement.
Fairchild
21
BP
Adding part dimensions - The size of the diode is 4.7mm x 3.5mm
Welcome to the forum @mzehr!
Based on the dimensions, overall shape, and manufacturer logo I was able to narrow it down to the following options: https://www.digikey.com/short/tp9z8h5h (52 items in list)
Unfortunately I was not able to find anything that matches the markings on there, it’s possible that this is an obsolete series or a very old part. If we could pin down the reverse voltage and average current there may be a good alternate in there, the issue is that I’m not seeing a way to link this item to a set of specifications that could be used for suggesting alternatives. Do you happen to know what voltage was being applied and how much current the diode was rectifying?
Hi Chris,
I don’t know the exact voltage that was being applied, but it’s used in a circuit that’s going to the gate of one of the phases of an IGBT module. The component is from a 480VAC VFD that was manufactured in 2023.
I can try working back from the IGBT to draw out the circuit and perhaps determine what control voltage would likely be across this component based on other components that are also connected to this component. My first thought was that this is a TVS type diode as there’s no polarity marking on it, but I’ve seen Zener diodes in this type circuit before.
If none of this info helps to narrow down the possible crosses, I’ll work on drawing out the circuit to see if that gives us a clue.
The IGBT on this drive was also blown and I’d like to try to determine this part before I go to the expense of ordering the IGBT.
Thanks,
Fairchild was bought out in late 2016. Not impossible for parts like that to sit on a shelf for ~6 years, but if somebody tried to save a buck by buying parts from sketchy sources, it might be part of the reason you’re trying to repair your device…
Anyhow, “BP” is a mark used by a number of manufacturers (example) for a 16V bidirectional TVS diode in SMB package; this seems consistent with what you’ve got there.
Thanks! I’ll dig into the circuit layout a little more to verify this component will work.