Custom hardware has poor Low Power performance

[KMeld.1]

Dear ST

As a follow up to my previous question (https://community.st.com/s/question/0D53W00001Tgf47SAB/high-power-consumption-in-low-power-examples:(

I'm using a custom board based on the STM32WB55CE6U MCU, design using the various application notes and Nucleo-WB datasheet/user manual.

The board does work, as I'm able to run my core BLE application with ADC/DMA and other functionality.

I've now started to implement Low Power (FreeRTOS tickless idle) using STOP2 mode.

The current consumption has dropped significantly (from 10mA --> 630uA during idle), but that is nowhere near the 3-6uA the BLE_HeartRate_FreeRTOS example uses on the Nucleo development board.

Digging in to the issue I've played around with the simple PWR_STOP2_RTC example, which uses ~3uA on the Nucleo.

Running the same (basically) software on my board, the consumption is never below ~80uA. I've literally soldered off all components but the basics - see pictures.

Are there some custom code, which need to be implemented for STOP2 to be optimal.

I've added code from the example in "stm32wbxx_hal_msp.c" and "main.c".

Running the binary from the example on my board yields the same result, so i do suspect my hardware.

All Capacitors are X5R or X7R and other components live of to standards in application notes.

Could it be bad PCB quality? Traces?

[KMeld.1 · Accepted solution]

Just realized my VDDRF was only connected to GND through the decoupling capacitor (was debugging an old board) and not VCC with decoupling... After hooking VDDRF up correctly with some wire, the board now only consumes ~4uA in IDLE-mode running FreeRTOS.

So I guess the answer is that The RF system can run with this wrong configuration, but will draw current!