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I have a sun battery which produces around 55V / 5A at most. I need to regulate this to 24V. I wanted to use the L7824 family, but they have a maximum DC input voltage of 40V so it would burn down. I was looking for some eaiser solution for this but couldn't find anything. Could you recommend a simple regulator circuit that would fit to this sun battery?

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If you use a linear regulator, you're going to waste more than half of the available power. I would recommend some sort of switching converter. That's a pretty high input voltage, though. I don't know of any good switchers offhand that will run with a 60V+ input voltage.

I would suggest taking a look at the power converter availble from Linear and TI. It looks like linear has a few that will work:

http://parametric.linear.com/External_Power_Switch_Buck_Controllers#!1646_Buck!1032_%3C=50!1033_%3E=60!1105_%3C=24!1034_%3E=24!1107_2:15!vinmin_50!vinmax_60!vout_24!iout_2

The LTC3810 looks like a good candidate - it will work on input voltages up to 100 volts and it can provide output voltages from 6 volts to 55 volts.

http://www.linear.com/product/LTC3810

It does take a handful of external components to work, but the datasheet walks through the calculation of the various passive components.

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  • \$\begingroup\$ Thanks for your reply! Would it change anything if the maximum voltage of the sun battery would be ~42V instead? The real life tests show that the voltage does not cross this 42V limit (the specs says other). \$\endgroup\$ – papaiatis Nov 11 '13 at 12:05
  • \$\begingroup\$ Well, you want to spec your regulator/converter for the highest voltage possible. If the converter only goes up to 50 volts and you put 55 on it, there is a good chance you will get a surpise visit from the genie of the magical blue smoke. Which, unfortunately, doesn't grant any wishes. \$\endgroup\$ – alex.forencich Nov 11 '13 at 18:05
  • \$\begingroup\$ Yeah I know that. Besides that, how about a 48V to 24V step down converter? Or similar? \$\endgroup\$ – papaiatis Nov 11 '13 at 19:13
  • \$\begingroup\$ It would work fine, presuming you don't exceed the input rating. \$\endgroup\$ – alex.forencich Nov 11 '13 at 19:32

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