We are using STM32L072KB MCU in one of our product development. Currently we are facing current consumption fluctuation problem in STOP mode of operation. (0.31uA to 0.61uA). What would be the root cause of this type of issue?

SKatt.1 · ‎2021-07-27

Test Condition

MCU Operating Mode- Stop

IO- all analog and floating

All peripherals- Disabled

Internal Regulator- Low power mode

PCBA- Only MCU , decoupling capacitor and boot select resistor.

Supply Voltage- 3.3V

Result-

IDD current fluctuate continuously.

Min- 0.31uA

Max- 0.61uA

Bubbles · ‎2021-07-28

Hello @SKatt.1 ,

this is normal and well in line with DS parameters.

The fluctuation you are observing is caused by the internal regulator, discharging and charging a small capacitor.

There is no need to worry.

J

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SKatt.1 · ‎2021-07-29

Thank You Mr. JHOUD your valuable input!

I was also suspecting the same possiblity...

I would like to add one more observation for the same. We have evaluated Nucleo -64 STM32L073RZ board for the same STOP mode test condition, where we did not observed any fluctuation in the stop mode current . It was sable to 0.41uA.

Could you please help me out to understand the difference between L073RZ and L072KB with respect to internal regulators?

Thanks and Regards,

Swaminath Katte

Bubbles · ‎2021-07-30

Hello @SKatt.1 ,

I just hooked up a Nucleo64 with early sample of L073RZ to a power analyzer and I see a lot of noise, ranging from 0.3 to 0.58 uA. It's more a sample variation, then also difference in capacity of the PCB and surrounding passive components. Is this approximately what you observe, or is that rather a saw pattern?

J.

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