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How do I create a negative 3V3 power supply from a 1 cell lipo?
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Commander Cloud:
Hello all,
I am a newbie teen designing a PCB for a project with a display, and the display I am set on using needs a -3V3 power source. How can I best and most efficiently create this power rail from a 1 cell lipo? (It is already protected and regulated to 3V3, fyi). Thanks in advance,
CommanderCloud.
madires:
By an inverting DC/DC converter.
artag:
For the simple case of inverting a power rail (and if the current demand is small), you might be able to use a 7660
http://www.ti.com/product/TL7660
tooki:
If it's an LCD that just needs the negative supply for the contrast pin, then you should also be able to use a cheap ICL7660 chip. Easy to work with and inexpensive, but limited to very, very small amounts of current. (Many 3.3V 1602 LCDs, as well as some large or extended-temperature versions, even at 5V, use an ICL7660 precisely to create the LCD contrast voltage.)
Edit: heh, great minds think alike, artag!
iMo:
http://elm-chan.org/docs/lcd/lcd3v.html
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