NUCLEO-F303K8 high power consumption while in Sleep Mode running on 3.3v

geokscott · ‎2023-12-15

I'm running the board on 3.3v, and as per documentation:

+3V3 power supply
Using the +3V3 (CN4 pin 14) directly as power input, can be interesting, for instance, in
case the 3.3 V is provided by a shield board. In this case the ST-LINK is not powered, thus
programming and debugging features are not available. When the board is powered by
+3V3 (CN4 pin 14), the solder bridge SB14 and SB9 (NRST) must be off

Solder bridges SB14 and SB9 are open. ST-Link should not be powered. Runs perfectly but the power consumption when in deepSleep is over 2mA. BUT, when I plug the micro USB into the computer (effectively powering up ST-Link) the power consumption drops to less than 20uA while in sleep mode. I reviewed the schematics of this board and cannot see what interactions could possibly be going on between the processor and the ST-Link circuit to cause this? Does anyone know why this extra load and how I can get rid of it?

Simon.T · ‎2023-12-19

Hello @geokscott ,

Is it possible to give more detail about your GPIO configuration ? Especially for the pins connected to the ST Link like debug pins, USART and MCO ? If they are floating, the Schmitt trigger input can produce over consumption.

I would recommended to either fix the voltage on these pins or put these pins as Analog input (to disable the Schmitt trigger input). You can find more detail by reading this application note: https://www.st.com/resource/en/application_note/an4899-stm32-microcontroller-gpio-hardware-settings-and-lowpower-consumption-stmicroelectronics.pdf

Best regards,

Simon

geokscott · ‎2023-12-21

Thanks for the reply. I tired all the application notes in the link, thanks for that. Nothing helped. I finally swapped out the board with a L432KC and the problem went away!

CORRECTION: The problem is still there with the L432KC board. I'm thinking the only way to fix this is to cut all ties between the ST-Link and the processor. But then I won't be able to program it anymore. I understand this is a development board, but why not make it able to do a fully functional final test environment by giving an option to remove the ST-Link via jumpers. I want to do a full test of my prototype but can't with the ST-Link getting in the way.