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I am trying to source (hopefully) a single power supply for my present project. From this single source I was thinking of using appropriate buck and boost converter circuits to fan out the various voltages I need.

I understand that with something like a basic DC voltage regulator, your 'excess' is basically dissipated by heat (which you have to watch out for/ensure to control).

Seeing with almost everything in engineering there is inevitably a 'trade off', I was wondering what the case was in terms of 'buck and boost' ?

For one, from some circuits I have looked at, I can obviously see they don't have 100% efficiency (though many are not all that bad)-- Though at the same time with the right IC these circuits are much simpler than the straight 'power/transformer' circuitry that would otherwise be needed.

In this sense, I am wondering what is the 'cost' of buck and boost-- is heat still a major issue ? Is it only a matter of a certain loss of efficiency ?

A bit of a basic question I know, but still trying to wrap my head around this.

Thnx.

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  • \$\begingroup\$ The more general term is switch mode power supply, or SMPS. Buck and boost are just two topologies of SMPS. \$\endgroup\$ – caveman Feb 27 '15 at 16:17
  • \$\begingroup\$ Cost ? They are more complex which can translate to expense, and they generate a lot of switching noise, which may or may not be well-contained. If it isn't, you need to take care that it doesn't affect your circuit's performance. An AM radio would be a poor application for a SMPS... \$\endgroup\$ – Brian Drummond Feb 27 '15 at 16:22
  • \$\begingroup\$ Yes, personally perhaps I should not have used the term 'cost' in the monetary sense, but rather in terms of what is the 'electronic cost' or 'trade off' for these types of circuits. Thanks all for the replies. \$\endgroup\$ – Anthony Balducci Feb 28 '15 at 11:21
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The basic trade off between a linear (step down only, and buck and/or boost switching regulators, aside from efficiency, is lower part count, easier layout, & heat vs higher part count, layout concerns, & noise.

Going with a module makes the first two moot, but the third is still an issue for audio or rf or high speed data. Switching supplies can cause interference in some cases based on their switching nature. Linear regulators on the other hand, can smooth out noise. In exchange, switching regulators are relatively cool, while linear regs heat up more as the current increases.

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Since the switching converters are using PWM to regulate the voltages, some issues may arise like ripple on the output voltage, EMI problems and electrical noise. As for "design cost", most of the switching converters require significant amount of external peripherals, like inductors, which take space and cost money. Additionally, some strict considerations should be taken when designing the PCB layout for such a PS to reduce the issues I've listed.

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