EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: rexxar on March 13, 2014, 04:33:34 am
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I'm working on an LED driver project, and I was planning on running the whole thing from a single lithium cell. I thought the mosfets I bought would saturate around 3 volts, but they seem to... not. To get this prototype working, I took the microcontroller off the battery supply, and stuck an L7805 on a 9V battery. This seems to drive the mosfets into saturation, and everything's fine.
Obviously a 9V battery hot-glued to the board isn't a real solution, so what would you do? I'm thinking of using a MAX1683 voltage doubler, then a 5V regulator to keep the fets and uC happy. I don't know if this is the 'correct' thing to do, though.
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You could make a simple voltage doubler with two MCU outputs generating psudo AC into a diode/cap. Check out Dave's video on exactly this
The current wouldn't be that high 5mA or so, it would depend how many mosfets you need to switch and how fast.
I'm not sure exactly what the mosfet in your circuit is doing but it should work fine to drive a simple mosfet switch.
Probably not enough current to drive a led array though, if that's what your doing.
A lower Vgs mosfet maybe in order. or a small dc/dc boost module.
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For the lazy:
EEVBlog #473 – Microcontroller Voltage Doubler (http://www.eevblog.com/2013/05/25/eevblog-473-microcontroller-voltage-doubler/)