Why do you plan to drive all the segments of a B7971? Do you realized that this would need a resistor on each cathode? If you use one anode resistor, the current changes depending on how many cathodes are grounded. This results either in tube damage or not working/darker display. I suggest to multiplex this tube.
About the mosfet, 21A or even 32A is overkill, but the problem is, that usually mosfets that have a low RDSon and GateChange, have a lot of current rated. If you use a Rsense of 25mOhm, the maximum current would be areound 3.5A@5V, so a mosfet with a few amps more should work fine, but low current fets usually have higher RDSon. This is why most DC/DC Converters use overkill Mosfet. Rdson and GateChange influence the efficiency of the circuit, so lower is better, your chosen mosfet has 160mOhm, you could go lower. I've used the FDPF44N25 a few times: https://www.mouser.ch/ProductDetail/512-FDPF44N25T The Inductor looks fine. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/9d7ba2df-af09-408d-9845-2ad70e3a593b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
