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I'm trying to design a mini workbench power supply to use for small electronics that is powered from the 12V rail of an old ATX power supply. I want it to be able to provide an adjustable voltage of 2V-30V and an adjustable current limit from 0-3A. Therefore, I'm going to need a buck and boost converters to do so. I have two ideas so far which is :-

-LM2577(Boost), LM2596(Buck) & LM350(Current Limiting)

My first idea is to connect a LM2577 boost circuit, LM2596 buck circuit and a LM350 current limiting circuit in series. Problem with this is I need to have two separate potentio to control the buck and boost. And another problem is I'm not very sure on the LM350 as a current limiter. Is it good and stable? Is there any other better current limiting circuit that can handle 3A

LM350 Circuit

-LM2577(Boost) & L296(Buck and Current Limiting)

My second idea is to connect a LM2577 circuit and L296 circuit in series. I have the same problem with this that I need two separate potentios and it can only adjust voltages from 5V-40V. However, it does have a built in current limiter. Is this current limiter stable?

L296 Circuit

Which circuit is a better idea or are there any better circuits that can be used? Are there any better boost converters or a chip that has all in one? And lastly how do I measure the current limit? Sorry for lots of question. A reply will me much appreciated. Thank you!

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A single Buck-boost converter would be nice, and Linear Tech has lots of them here

They also have some nice, free, simulators here

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    \$\begingroup\$ LT also has a slick method of using a buck as a pre-regulator for LDO outputs: linear.com/docs/45095 \$\endgroup\$ – Peter Smith Aug 19 '16 at 10:38

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