Does anyone know of a little AC/DC switch mode converter module that can take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k qty would be nice, availability in the US would be even nicer.
All I see is 24VAC to 12VDC and placing two in a row costs effiency. Sure, I could roll my own again but this time we want to avoid NRE and agency hassle (EMC et cetera).
:Gents, : :Does anyone know of a little AC/DC switch mode converter module that can :take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k :qty would be nice, availability in the US would be even nicer. : :All I see is 24VAC to 12VDC and placing two in a row costs effiency. :Sure, I could roll my own again but this time we want to avoid NRE and :agency hassle (EMC et cetera).
I don't think there are any 24Vac input converters off the shelf - almost zero demand I would think.
Why not use one of the 6 - 10W, 18-36V input DC-DC converters (eg. V-Infinity)? Provide a bridge rectifier and bulk filter cap in front of it. A few bucks for the BR and cap would keep it under $20 per unit in 1K quantity.
You could just add a bridge rectifier and a filter cap. This would widen your selection to several hundred of the SMPS's that have a max input to 36 or 75 Vin. Cheapest one I could find with a quick search is
That's solution B, if I really, really have to. In this case that would require some regulatory scrutiny though because the input side would now not be "taken care of by module" anymore. If that wasn't an issue I'd just roll my own because then I won't have to deal with those dreaded
50C or 60C derating issues that "professional" switchers often exhibit.
It used to be very popular in Europe but I haven't seen any industrial switch gear there in some 15 years. All the power contactors for huge motors and such were run on 24VAC. Up to 30-50A. Larger ones still had
24VAC "control contactors" but they'd drive huge 230VAC contactors, the kind that sounds like a gunshot when they engage.
While studying for my masters I assembled gear like that because those jobs paid quite well, compared to bussing tables :-)
I still have a discarded supply transformer for a cabinet that was sold to me at scrap metal price. 24V, one kilowatt (!). That was from an older cabinet two stories high where you needed a ladder to get to some of the contactors. The secondary of that transformer consists of soaked-cloth insulated copper bar that was formed around the primary using a wooden mallet.
Looks like I hafta :-(
That's why I posted, was hoping for a silver bullet that lets me avoid it.
Yes, sorry, should be isolated but we could make it work without. AC/DC converters are generally isolated though because they use bridge rectifiers.
Yes, and we'd put one on there anyhow because it affords some surge protection.