Nucleo board consuming too much on external power supply

[mbruder]

Posted on December 15, 2015 at 13:32

Hi!,

I've got a Nucleo board, it's a L152RE Rev C.

I've tested the example PWR_STP_RTC available for these boards and the board successfully lowered it's consumption from 9.3 mA (in running mode) to 1.5 uA (in stop mode).

On the other hand, when I power the board externally from an external power supply of 3V3, the consumption is around 9.5 mA (in running mode) and 415 uA (in stop mode).

Does anyone understands why is these happening and what can I do to reduce consumption?

I expect to eventually consume as little as I can while powering my project with batteries. 

Regards,

Mart�n

#external-supply-batteries-stop

[mbruder]

Posted on December 15, 2015 at 22:26

Ok, I actually found what it seems a bug in the hardware design of these Nucleo Boards.

Resistor R23 has one of sides connected to +3V3 when it should be connected to +3V3_ST_LINK.

This powers with lower voltage the branch +3V3_ST_LINK when the device is being powered from an external supply in +3V3. 

Does anyone knows how to report these?

[Tesla DeLorean]

Posted on December 15, 2015 at 22:45

Does anyone knows how to report these?

 

To your local ST sales rep or FAE? I'll flag the post here, but it's not going to change the tens of thousands of boards out there. Mod the board as you need, document for others who might use your solution, and move on.

[mbruder]

Posted on December 15, 2015 at 23:10

Thanks for the quick response. 

I'll try contacting ST France.

I'm not expecting to change the boards already made, just let them know for a further revision. Also, it would be nice if there was a space with ''known bugs'' for us to be able to dig in case we are not sure whether we've found one or not.

Anyway, I found these just before leaving home. I removed R23 and seemed to solve the problem. I was even surprised to see I could program the MCU again from the PC.

I didn't try to debug though... I'll see if I encounter something different tomorrow.

Thanks again!