In sleu116.pdf in the schematic "Figure 2" there is a AT24C64N Flash connected to the PCM2706/7.
This type of flash needs 2x8 bit address to read/write.
But as reading external USB-descriptors did not work out in my design at all, i found out (by scope traces), that the PCM2706 seems to do just a 1x8 bit address read after reset:
Startcond. / 0x90 / 0x00 / Rep.Start / read .... / Stopcond.
But to address the AT24C64 it would be necessary to do this:
Startcond. / 0x90 / 0x00 / 0x00 / Rep.Start / read .... / Stopcond.
Now i suspect, that there's just crap in the sleu116.pdf - the AT24C64N is simply not usable for this case; it has to be a smaller one like the 24C04 - am i right?