2017-09-13 03:38 AM
There's no source of PLLI2S signal mentioned anywhere else on the schematics, nor elsewhere in RM0360 (although the string occurs quite often as it's the name of the PLLI2S sub-module).
My personal guess is, that this MCO2 input is fed from PLLI2SR, i.e. the R output of PLLI2S submodule; but I'd love to hear some qualified comment from ST.
Thanks,
Jan Waclawek