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Power up STM32F407 Discovery using a 11.1V Battery

Question asked by wald.yannick on Apr 16, 2015
Latest reply on Apr 16, 2015 by Clive One
Hello STM32-Community!

I read in the document UM1472 that the 5V pin can be used as a input of an external power supply. I want to power up my board by using one battery (11.1V). I was thinking about a simple voltage divider such that I can draw exactly 5V. The problem might be that connecting a load to the divider circuit will change the impedance and therefore the 5V output of the divider cannot be guaranteed.

Would the problem be solved if I connect an voltage follower to the virtual ground of the voltage divider as seen in the picture?

What do you think and how would you solve this problem by only having resistors and opamps?