Power Consumption Calculations

abdelrahman-kadah · ‎2024-06-25

Hello everyone,

We are working on a low power project.

We selected MCU STM32G030K8T6 for that project.

Before developing the project, we tried to verify the power consumption values found at the datasheet by trying a simple code operating at 2 MHz that makes all GPIO pins floating, enables the low power run mode, enables the power down flash mode, and then enters the sleep mode.

We used the Joulescope to measure the consumed current in case of input voltage 3 V at temperature 25 C.

We found the current is much larger than values found on the datashseet.

In the datasheet, the typical value of current in sleep mode at 25 C is ~40 uA, and our value is ~230 uA.

Why that happens??

You can see the code and the results in the attached files. Fig. 1.PNG Fig. 2.PNG Fig. 3.PNG Fig.4.PNG Fig.5.PNG

Simon.T · ‎2024-06-25

Hello @abdelrahman-kadah ,

In your code you are using the HSI16 internal clock as system clock while the datasheet table show the consumption using HSE bypass as system clock.

To have an idea of the correct value in low power sleep you need to add the HSI16 oscillator power consumption which is typ:155µA (see table 38).

Best regards,

Simon

unsigned_char_array · ‎2024-06-25

Is the MCU 25C or just the ambient air? MCU is warmer than ambient due to internal heating. And if the board is warmer that adds to the temperature as well. If current consumption scales linearly and the MCU is 35C, then you can get 214uA worst case instead of 175uA. So that could explain part of the problem. But it's absolutely not enough to explain all of it. Most MCUs have an internal temperature sensor.

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