The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is because of interactions with the millis() and delay() functions, which share the same internal timer used to generate those PWM outputs. This will be noticed mostly on low duty-cycle settings (e.g 0 - 10) and may result in a value of 0 not fully turning off the output on pins 5 and 6.
reading this i would expect an error of +-10%,
The frequency of the PWM signal is approximately 490 Hz.
The frequency of the PWM signal is approximately 490 Hz on pin x, y, z and 980Hz on pin a, b, c.
I agree with lesto. The infos in that page of the Reference aren't accurate.PWM frequency is ~490 Hz on pins 5 and 6 (timer 0), and ~976 Hz on pins 9, 10 (timer 1), 11, and 3 (timer 2).