I want to build a circuit that provides USB power from a 12V battery (lipo or car battery).

I have an iPad that draws 2A from its charger: So I'd like to get up to 10W output.

What's a good choice for IC and inductor (and other components) for making this?

  • \$\begingroup\$ This strictly a shopping question, so should be closed. There are many buck ICs out there. What you want is not unusual, but there are some tradeoffs to make. Look thru the Linear Tech, TI (which now includes Nationa), ST, and other web sites. Actually that bunch will be enough to find a number of suitable chips. \$\endgroup\$ Apr 22, 2012 at 18:20
  • \$\begingroup\$ A better question would investigate what tradeoffs are involved when looking for a SMPS controller in this power range. Inductor tradeoffs has been covered here: electronics.stackexchange.com/questions/15260/… \$\endgroup\$
    – tyblu
    Apr 22, 2012 at 19:07
  • 2
    \$\begingroup\$ @tyblu You should not change what is being asked after someone (like me) has already answered the original OP's question. You can correct and improve, but not ask more than what the OP was asking (otherwise, start your own question). That makes my answer look out of place, and that is not fair. Someone downvoted it, and it was perfectly valid for the original OP question. If this has to be closed, close it, but no one should be downvoted for providing a valid answer to a question (being later closed or not). Thanks. \$\endgroup\$
    – Telaclavo
    Apr 22, 2012 at 20:56
  • \$\begingroup\$ I downvoted it as it is a shopping-type answer. Questions and answers on this site are publicly editable such that they can be improved for its audience. The goal isn't to provide the OP a solution, though that is usually the outcome, but to add value to the site with quality Q & A's. I will revert the question and reinstate my downvote. \$\endgroup\$
    – tyblu
    Apr 22, 2012 at 21:45

1 Answer 1


Be careful not to blow your iPad. If you don't have experience with power electronics, you can buy something like this, a 2A DC-DC switcher module that is a pin-compatible replacement for the 7805, but doesn't require a heatsink.

enter image description here

  • \$\begingroup\$ Whoever downvoted this, read my comment above. \$\endgroup\$
    – Telaclavo
    Apr 22, 2012 at 20:57

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