The DCO is factory calibrated with plus/minus 3.5 % accuracy across the full operating temperature to 6 different frequencies. This combined with the flexible divider system is good enough for many applications. It is also guaranteed to plus/minus 2 % accuracy if the normal temperature is between 0 and 50°C. The FR572x devices can only run up to 8 MHZ, so the second bit of the DCORSEL register is only selectable for FR573x devices.