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Difference between Run mode currents in the datasheet

na.1
Associate II

what is the difference between these below currents

– 84 μA/MHz run mode vs Run mode current of 9.45mA in the below table

I always confused which current i have to consider while doing power calculations.

like uA/MHZ when to consider and with out indicating clock only showing mA current consumption.0693W00000QKNukQAH.png0693W00000QKNv9QAH.png0693W00000QKNvYQAX.png

7 REPLIES 7
Andrew Neil
Evangelist III

"what is the difference between these below currents"

That's given in the titles of the tables:

  1. The first one is a maximum IO current rating - it's how much current the device can supply to IOs.
  2. The second one is current consumption in Run and Low-Power Run modes;
  3. The third one is current consumption in Sleep and Low-Power Sleep modes.

"like uA/MHZ when to consider and with out indicating clock only showing mA current consumption"

Current consumption of the chip itself will always depend on how fast it's running - the faster it runs, the more current it takes.

The current that a pin can source/sink is a fixed limit - it doesn't depend on speed.

0693W00000QKPEqQAP.png

Write it as a normal sizable and searchable text. And what's with those super important "your/chip/And" words with underlines?

Of course you didn't tell what MCU you are using...

And at 80 MHz the current consumption with while(1) is 99 uA/MHz, which makes 7,92 mA in total. The rest can be consumed by many things, including the debug interface. It's described as issue 3a here:

https://community.st.com/s/question/0D53W00001bnh8dSAA/how-to-enter-standby-or-shutdown-mode-on-stm32

@NA.1​  Why on earth are you posting your reply as an image??

na.1
Associate II

Sorry previous i got an error while posting it's not taking the text i written thats why i do t have choice to post the text that's why i came with image

na.1
Associate II

Hi Andrew/Piranha sorry for posting that i age underlined texts are nothing but grammer suggestions leave it.

My concern is to calculate the load on the rechargeable battery by the ultra low power MCU stm32l462ret6 .

While taking ​active or Run mode current before i am not have enough clarity i mean what exactly Run mode current represents.

​And another thing is can you please suggest in active state which currents have to consider for power calculation

@na.1​ "what exactly Run mode current represents"

Exactly what it says in the title of that Table!

There should be separate documentation of what the on-chip peripherals consume.

"which currents have to consider for power calculation"

For battery life calculations, you need to consider everything that gets drawn from the battery - including everything that's external to the STM32.

Rather than trying to calculate it, it's probably better to measure it using something like the X-NUCLEO-LPM01A STM32 Power shield and associated software:

https://www.st.com/en/evaluation-tools/x-nucleo-lpm01a.html

That way you can get a real picture of what your system is actually consuming in its actual operation.