Nucleo64 Power Measurement

[Konami]

Posted on February 26, 2018 at 17:34

I'm measuring the current on JP6 (IDD) and I see 4mA at the lowest when running the Power_Management sample or even holding the MCU in reset. I am powering the board via the USB connector. Is this incorrect?

I've tried using SLEEP_MODE, STANDBY_MODE, and STOP_MODE defined, and they all show around 4mA

Nucleo-F411RE

[Konami]

Posted on February 26, 2018 at 19:08

I had multiple definitions of SLEEP_MODE so I was never running STANDBY_MODE code. 4mA seemed really high for sleep but I guess it makes sense with the 100MHz clock

[Bogdan Golab]

Posted on February 26, 2018 at 19:12

Yes, I think so. You can configure all unused pins as analog (CubeMX has a checkbox to do it automatically) to reduce even more current. I have not verified it and do not know what is real gain.

[Andrew Neil]

Posted on February 26, 2018 at 19:23

This would be bad design....

No - it's just a fact of life.

In the final application, you would not have an ST-Link present at all.

Trying to achieve uA 'sleep' (small 's') currents requires very careful attention to the fine details like this.

You also have to pay careful attention to other chips connected to the MCU - such as sensors, etc ...

[Konami]

Posted on February 26, 2018 at 19:29

I agree these things should be taken into account when working with a custom board but the documentation for the Nucleo board states that this header is specifically for measuring uC current. Either that's true or it's not and they should specify that x,y,z needs to also be removed.

For the record I am able to measure 2.3uA in standby mode on IDD with no modifications to the board and power being supplied by the mini-USB connector.

[Bogdan Golab]

Posted on February 26, 2018 at 19:31

Generally, yes. But in this case I cannot see the leak from VDD toward 3.3V. The VDD has potential lower or equal the 3.3V.

MAybe I am wrong.