STM32L072 - VDD_USB Supply Current (for PA11, PA12)

[Andrew Neil]

PA11 and PA12 are powered from VDD_USB.

So, to use PA11 and/or PA12, we have to have the VDD_USB domain powered-up.

I can't find any documentation of the expected VDD_USB current draw when the USB functionality is not used.

In a previous project, I remember noticing that it did cause some extra current drain - but I don't recall how much.

So the question is: what is the expected VDD_USB current draw when the USB functionality is not used?

(this is with specific reference to the B-L072Z-LRWAN1 board - where PA12 is used to power the TCXO)

[Andrew Neil]

Related: https://community.st.com/s/question/0D53W00001FncyTSAR/bl072lrwan1-why-is-the-tcxo-powered-from-pa12

[waclawek.jan]

While it is a legitimate question, I believe that consumption of VDD_USB itself (without current flowing out of PA11/PA12) is negligible, see my reply in that other thread.

JW

[Andrew Neil]

Shame it's not documented, though.

(and a shame that I didn't properly document my own findings in the previous project)

I guess I'll just have to measure it again ...

[waclawek.jan]

I have an 'L0 Disco on my desk (the one with the e-paper), and it would be an interesting exercise to measure - but, unfortunately, the target 'L053 has the VDD_USB pin hard connected to VDD...

JW