STM32U083C-DK and X-NUCLEO-LPM01A, IDD Higher Than Expected in Sleep

[stakata]

Short story: the X-NUCLEO-LPM01A is displaying higher current in low power modes than expected by the STM32U083 datasheet and the numbers shown on the LCD of the STM32U083C-DK.

Set up:

I followed this post to connect the X-NUCLEO-LPM01A to the STM32U083C-DK. I removed the JP7/IVDD jumper from the STM32U083C-DK.

Connections:

STM32U083C-DK	X-NUCLEO-LPM01A
left pin of JP7 (VDD_MCU)	CN14 pin 3 (VOUT (+))
CN13 pin 8 (GND)	CN14 pin 1 (GND)

I set the X-NUCLEO-LPM01A to output 3.3V using the joystick.

I downloaded the sample package from: https://www.st.com/en/embedded-software/stm32cubeu0.html

I opened the project in IAR embedded workbench version 9.60.2 from STM32Cube_FW_U0_V1.1.0\Projects\STM32U083C-DK\Demonstration\Demo\EWARM.

I started a debug session from EWARM connected to the STM32U083C-DK thru the on-board USB-C port ST-LINK.

At the time of the measurements, a debug session was not active. Both boards were connected to the same USB hub.

Measurements:

When the demo code is running, the X-NUCLEO-LPM01A reports about 4.8 mA. When I navigate to ULP -> STDBY on the menu, the LCD goes blank for ~30s, the menu button is unresponsive and the X-NUCLEO-LPM01A reports about 1.36 µA.

When I select ULP -> STOP1, the X-NUCLEO-LPM01A reports about 136 µA but the STM32U083C-DK shows 3.3 µA on its LCD.

Here's the full list of modes and reported current.

Mode	STM32U083C-DK LCD	X-NUCLEO-LPM01A LCD
STDBY	Blank	1.370 µA
SLEEP	101 µA	289 µA
LP SLP	62 µA	203 µA
STOP1	3.3 µA	135 µA
STOP2	825 nA	120 µA

Photos of setup and one power mode executing:

Running prior to select buttonAfter button press selecting STOP2

Questions:

1. Please check the 1.1.0 version of the STM32CubeU0 demo package. Is there a reproducible problem with the STDBY power mode where the LCD goes blank and will not respond to button press?
2. Are the reported power numbers on the LCD of STM32U083C-DK static or dynamic? In other words, is the STM32U083C-DK measuring power consumption, or is the value shown on the LCD hard-coded based on what the datasheet expects?
3. Does my physical set up look correct for the use of the X-NUCLEO-LPM01A with STM32U083C-DK?

Thank you for your help.

Steve