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Background: I am software engineer with a limited knowledge of electronics. This is a n00b question.

I want to design a circuit to step down DC voltage from about 24V to 12V. I have tried a 7812 linear voltage regulator but the chip heats up a lot even when attached to a heat sink.

I have now decided to use LM2575 / LM2576 instead, since they are more power efficient than the 78xx series. But these chips require some more components (like diodes, registers, etc), before they can be used to supply power. I have figured out this circuit with the help of a handbook.

I now want to run a simulation of this before I dare to fry the chips (which, btw, were quite difficult to acquire locally).

What is the best way to simulate such a circuit using free/open-source tools? I tried searching for models for LM2575/LM2576 without success.

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    \$\begingroup\$ Have you heard of the 3-transistor Black regulator by Roman Black? It is an efficient 24 V to 12 V switching voltage regulator using common, easy-to-acquire parts. \$\endgroup\$
    – davidcary
    Jun 16, 2013 at 3:20

2 Answers 2

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TI's web site also offers the Webench designer (brought over from the National web site when TI and National merged a while back). You can find it right on their home page and pick the "Power" tab.

The Webench designer helps you design a switching VR, shows you a schematic, BOM with suggested standard components and provides budgetary cost comparisons between competing designs. The tool also will simulate the design and show analysis results.

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  • \$\begingroup\$ I had found the Webench a little too automatic. While it suggested a lot of designs, I couldn't find how to choose the specific ICs I wanted (LM257x). Will give it another try now. \$\endgroup\$
    – HRJ
    May 14, 2013 at 13:11
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From the TI website for that part simply follow the links marked software and you will come across Power Stage designer.

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  • \$\begingroup\$ Thanks for the link, but I can't see how this would be useful to me. I think it shows how to design a LM2575 rather than how to use it. \$\endgroup\$
    – HRJ
    May 15, 2013 at 3:34

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