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High noise level in the analog domain on nucleo-H743zi

Senior III

I discovered that Ethernet module on the nucleo-H743zi generates a lot of interference for analog domain. I thought, that if peripheral devise was not configured in the software and was not given explicit permition to run, it should stay in power down mode. Turns out, that it is not the case with Ethernet chip on nucleo-H743zi. IC is running at full power, consuming 45-90 mA of current just for output stage (measured with L1 de-soldered), and creates a high power interference for all analog circuitry, ADC, DAC etc. This is especially troubling for boards with VREFBUF and VDDA connected.

( basically, should apply for all nucleo-144 ethernet equipped boards!) .

Reading LAN8742A DS, I noticed that it has :

3.7.2 MODE[2:0]: Mode Configuration, and has an option to initialized in power down mode during power-up sequence. Otherways, it would be nice to have a software patch to put Ethernet into "off state".