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For a robotics project I need to use a buck regulator to power a mobile computer from a 22V LiPo battery. I am currently using this LDO regulator and am having issues with it getting very hot. Using a large heat sink, the regulator functions without shutting off due to high temperature yet since this is a mobile application I am worried about how much energy I am wasting in the form of heat. If my load is pulling 1A at 12V, is it true that the regulator is dissipating (22*1) - (12*1) = 10W? I had originally selected a linear regulator over a switching regulator because I wanted a clean, stable DC output for my computer to operate on.

I am now thinking about trying a "switching regulator" because of how most of these devices are >90% efficient! I have had a lot of trouble finding a switching regulator that could provide a 12V output (most of them seem to provide only a few volts of output, does anyone know why this is?). I found this switching regulator though which provides my needed output and is in the 90% efficient range. Does anyone have any suggestions for other switching regulators? I have to have a totally integrated package (for example, I don't have room to attach external caps or inductors for my application).

Also, is the only reason someone would choose a linear regulator over a switching regulator because they usually provide higher voltage outputs? Is using a switching regulator with a computer really not a problem?

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  • \$\begingroup\$ If supply noise is a large concern you can always use a switching supply to get it down in the 14-13v range and then use a LDO to give a nice smooth 12v, then it would only need to dissipate a couple watts, best of both worlds \$\endgroup\$ – Gorloth Apr 5 '13 at 19:58
  • \$\begingroup\$ as suggested by Gorloth, you might consider using both. [this document talks about such thing linear.com/docs/11877]. Also you can find a lot of cheap switching regulators that uses the LM2596S on ebay, just search for that part number. \$\endgroup\$ – Fahad Alduraibi Apr 5 '13 at 20:19
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  • Integrated DC-DC buck regulators for 12 Volts 1 Ampere do exist, from manufacturers like Recom, R-78C12-10. These are drop in replacements for the popular 7812 type linear regulators - thus, totally integrated packages, as desired.

  • Yes: If your load is pulling 1 Ampere at 12 Volts with 22 Volt source, the regulator is dissipating (22 - 12) * 1 = 10 Watts as heat.

  • If desired power quality is not met by the switching regulator chosen, a hybrid approach, such as using an adjustable integrated switching regulator set to 14 Volts or so, followed by a low drop-out linear regulator, would give the best of both worlds - low heat, yet low ripple.

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