Unexpected High Current Consumption in STOP2 Mode on NUCLEO-U545RE-Q

[xiangpu2001]

I’m performing low-power consumption tests using the NUCLEO-U545RE-Q development board. However, after entering STOP2 mode, I observed that the current consumption remains around 23 µA, which is significantly higher than the typical values stated in the datasheet (DS14216 Rev. 4, Table 59, page 162), where STOP2 mode is expected to consume only a few microamps. I’d like to understand what might be causing this discrepancy.

Test Configuration:

1. Hardware Platform:

   • ST official development board NUCLEO-U545RE-Q.

2. Clock and Peripheral Settings (STM32CubeMX .ioc):

   • All peripherals are disabled, including the RTC.

   • The system clock source is MSIS at 16 MHz.

   • Both HSE and LSE oscillators are disabled.

3. SRAM Configuration:

   • Only SRAM2 (64KB) is enabled.

   • SRAM1 and SRAM4 are disabled.

4. Power Supply Configuration:

   • The MCU is configured to use SMPS instead of LDO.

5. Test Environment:

   • Room temperature conditions (approximately 25 °C).

Given the above setup, what might be the reason for the higher-than-expected power consumption in STOP2 mode?
Are there any additional settings or recommendations to further reduce the power usage and match the datasheet specifications?

[Andrew Neil]

Check the Nucleo board schematics very carefully for things which could be leaking current.

Pay particular attention to connections to the ST-Link - unfortunately, on this board you can't just break the ST-Link off.

[Jojo_]

What source are you using to power the board and measure the current ? It would be useful to know this, as well as any other connections you might be using.

From first impression, it is probably as Andrew said, The extra consumption you are noticing might be due to the ST-LINK powering something you don't want to power.

[Andrew Neil]

Also, you have disconnected the programmer after programming?

And power-cycled - not just reset - the board?

It would help to post a minimum but complete example which demonstrates the issue.