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Author Topic: A Switching Power Supply? The TL2575  (Read 614 times)
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Hi, everyone,

With a collection of people running so many standalone and low-voltage applications on the Arduino, is there any reason why people aren't replacing their 5[V] regulators (usually the classic LM7805) with a switching regulator?  In terms of efficiency, the TL2575 is wayy more efficient at about 96% compared to about 40-to-50% for the LM7805.  According to the datasheet, it can handle up to 40 [V] DC input and supply an 5 [V], 1 [A] output.

It seems like a win-win here.  Most of these switching regulators take a lot of extra calculations to setup, but this one seems much more straightforward.

Here's the link to its datasheet: (PDF!)
http://www.ti.com/lit/ds/symlink/tl2575-12.pdf

Thanks again!  (I could be totally overlooking something here!)
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The thing you are overlooking is that there are more components needed to use a witching chip that a linear regulator. Those components have to be of a higher quality, especially the capacitors so often it costs more.
The other thing is that to get a good stable a stepping regulator you need a PCB layout that is good. Many professional engineeres I have worked with do not get this right first time and the PCB design goes through many iterations before it is correct.
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is there any reason why people aren't replacing their 5[V] regulators (usually the classic LM7805) with a switching regulator?

I can think of a few: costs, size, complexity, sourcing, etc.

Your mcu consumes very little current, on the order of mas. If you need materially more than that, you have gone down the wrong path and you would prefer in those cases that your regulator burns up - than to damage your mcu.
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If I wanted to save power I wouldn't use a regulator at all. Read this:

http://gammon.com.au/power

You can get consumption down to the nanoamp range by using various techniques. One of them is to not use a voltage regulator at all. Two or three 1.5V batteries will provide sufficient voltage for the processor to run.
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I think most people would prefer that short circuit or thermal overload protection engage than anything burning up.  But yeah, ultimately it comes down to simplicity, ubiquity, and cost.  The LM7805 is available anywhere and everywhere.  It's a staple, people have heard of it, know how to use it -- it's about as easy to use as a component can be, and it's dirt cheap.  The load required by most digital circuits is so low that efficiency and heat aren't high priorities.

For those where this is not the case, of where the input voltage is substantially higher than 5v, I often do recommend a switching regulator.  There was a thread on here a few days ago where we all suggested either switching, or a power transistor using the LM7805 as a controller.  So nah, you're not missing anything.
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