joamanya:
I'm driving a DC motor and I need 20Khz PWM, but doing that it becam that my range is from 0 to 100, so you recomend me map it?
First, why do you feel you have a need to change the arduino default PWM frequency to 20khz just to modulate the power going to a simple DC motor? Only when we fully understand your need/justification can we work towards a 'best' recommendation.
Lefty