4 years ago.

Power supply for NUCLEO-F303K8

Hello everyone!

I'm trying to understand how to properly supply the NUCLEO-F303K8 board. I don't fully understand a lot of electric theory and I'm scratching my head about what to do.

At which voltage can I run it? And how flexible is that value?

I'll make a practical example for clarity. I want to power the board through a 3.7V LiPo rechargeable battery and I read on the manual that the device can run on either 3.3V or 5V depending on where the supply is received. Fine, but... Can I still use that intermediate 3.7V value? What power mode will I use to input it: 3.3V or 5V?

The alternative would be to use a 4.8V NiMH rechargeable battery pack, but the LiPo solution is more compact and even cheaper all considered.

Thanks for your help

1 Answer

4 years ago.

Any time the voltage is higher than the maximum rating you will have a problem. That said you can not feed a 3.7 volt power supply like your battery into the 3.3V input as it will damage the processor. So what to do? You will have to feed the power into the 5V external input. The particular 5V to 3.3V converter on the Nucleo board can take a low voltage and keep running but it may not work for as many hours as you maybe would like.

Ok! Thank you very much. The application is just a small prototype of a rover for experiments so I guess having a lower voltage wouldn't be much of a problem.

I've read online about power boosters that allow to get 5V output out of 3.7V LiPo batteries (Adafruit makes them), and the device is about 15€, do you think it would be worth the investment?

posted by Nicolò Bagarin 27 Dec 2016

You don't want to convert up to 5V. You would want a boost converter that generates 3.3V instead. That would power the processor directly. When the 5V enters the board it has to be converted back down to 3.3V. When you do a double-conversion then you waste a lot of energy unnecessarily. If you think you need the extra energy that a boost converter would provide (and it will) then it might be worth the investment. If you're just exploring then no, I would just connect the battery to the external 5V input. Be sure to review the Nucleo 32 reference manual on how to connect to the external power supply input correctly.

posted by Bill Bellis 27 Dec 2016