Sorry, my bad. I should have explained what my application is and what features I need so I will (hopefully) explain all there is to know in order to better choose what IC I need.
What I wanted was to do a supply for the filament of some VFD tubes. I chose the MP1584 as the converter from 24v/12v to 3v, the other supplies have similar needs, just different voltage and less current. What I was searching for was:
- Overvoltage protection: just a volt over and it would cause permanent damage to the IC. I know it’s difficult to find a low voltage protection so I am also happy with a 20v+ limit. That way I protect the tubes from a short in the supply chip.
- Slow ramp up: as the cold filament has less resistance, at start up there is a quite big (enough to lower some life times, but not enough to blow them) inrush current, so I needed a really slow start time, around 0.5sec, even better 2 seconds.
- Current limiting: not fundamental but in case there is still some inrush I should be able to limit the current to max 110mA or so. If that is not possible I’m happy with just a short circuit protection, which would protect in case the supply goes bad and jumps to 24v.
- A power good indicator pin: this will allow me to (in software) delay the start of the anode supply (this is to minimize wearing out and maximize lifespan)
- As the voltage is low I need an external supply, much like the MP5083 does.
- Last but not least: I want this part to be available, on Mouser/TME/MPS. If you look on mouser almost everything is out of stock. That’s why I chose the MP1584 as the supply: there are plenty of modules and this IC is really popular. This is the major limiting factor. there are a lot of cool ICs out there if only were they available for purchase.
The MP5083 is almost perfect for what I need, but I need really long startup times and pretty low current limit. One option is to use some supply IC with an integrated slow start, that would be absolutely perfect. Unfortunately, i haven’t found such supply chip yet.
I would love any suggestion and any help in my quest for finding the perfect IC for my application. Let me now if anyone has any clue on what I could use.