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I want to be able to make small switched power-supplies on the same board as some tiny projects, but I can't seem to wrap my head around the design parameters.
I've been looking at what's in phone chargers and monitors and stuff, but no two designs seem to use the same SMPS control chip or transformer. Are there no "standard" SMPS control chips, like there are standard linear regulators and op-amps and what not? As for transformers, there are thousands and thousands of them on sites like Mouser, and I've no clue how to select amongst them.
Surely there must be some more-or-less standard way to make a small and cheap SMPS? All I want is primary/secondary isolation and a few hundred mA out, at the very most.
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>Are there no "standard" SMPS control chips
Some chips are more popular than the others, but otherwise no.
>As for transformers
Those tend to be custom wound.
Use normal transformers and limit the switching stuff to the low voltage side instead.
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Here is a circuit I have used many times. I have added a variable resistor the 5v side to make it have voltage variable.
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>>1154435
>normal transformers
You mean those that accept 50 Hz? But they are huge.
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>>1154439
>I have added a variable resistor the 5v side to make it have voltage variable.
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>>1154474
kek
i use a laptop power supply & LT1085 5A + 10 turn pot
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>>1154430
How about you check out The list of Linear Technologies programs and keep an eye out for powercad2, or obtain a free license for powerplay and then you will be able to select different chips, your ratings and will be served with a recomended and calculated circuit.
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>>1154481
>laptop power supply & LT1085
That's a bit half-assed. Why not just open the laptop PSU and solder a pot in the feedback sense line to the PWM chip?
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>>1154497
>suggesting proprietary software
That's funny, Anon.
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>>1154500
laziness, the power supply is a sealed dell
and the linear regulator is rock stable under all loads and voltages i've used. whenever i try just adding a pot to a smps at some point they become unstable at some voltage & load. i'd probably have to change some inductor/filter/cap inside the thing.
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>>1154504
Often the designs just derive from the datasheets. I didn't know you were doing a full blown project for a company since you ask on here.
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>>1154509
As good of reason as any I guess.
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>>1154430
Use one of online tools to design.. NPX has one Webbench can design PSU...
Biggest problem is get ferrite trafo right, I think NPX tool is much better in this way.
there you go .. link for online tool by NPX
http://nxp.transim.com/fb/design.aspx#undefined
Just a tip. playing with mains don't get killed ..
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>>1154798
Interesting. It does indeed seem to suggest winding the transformer manually. How does one get transformer cores? I haven't found them for sale on Mouser or the other usual suspects.
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>>1154834
>"A few hundred mA" 6.3V transformer is roughly comparable to a match box.
Well, yes. For small projects, that might well mean a doubling of the PCB.
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