Electronic – Would the FCA47N60F work for a ZVS flyback driver

component-selectionfailurehigh voltagezvs

I have built a few flyback drivers from 555 controlled to the ZVS. I always have one problem, the power transistors keep burning out. For the ZVS driver, I used the IRFP250 and keep having the problem of transistor failure over about 24 volts for the input. Here's a schematic of the ZVS.

enter image description here

I recently ordered some FCA47N60F 600 volt 47 amp MOSFETs on sale at electronic goldmine. Would these transistors work with the circuit, or are there specific transistor properties needed for the circuit?

Best Answer

You haven't provided any measurements taken on the circuit with the original parts, so it's pure speculation why the old ones failed. Excessive power? Bad gate drive? Avalanche? Excessive dv/dt? If we knew what killed the old FETs, it makes choosing a replacement much less based on guesswork.

On paper, The Fairchild parts are "better" in several key areas: \$V_{DS}\$, \$R_{DS(on)}\$ and avalanche capability. However, the total gate charge is higher, meaning the device will switch slower than the original part.

In my experience, it's very difficult to judge solely based on paper. I've seen MOSFETs which "look" better in all areas end up burning more way power than the originals, or fail catastrophically. Since several parameters appear better, try the substitution and see if your reliability improves.