On 1/6/25 09:38, Rob Herring wrote:
The minimum PWM is presumably 0, E.G. signal always low?
I'm talking about the duty cycle needed to start the fan spinning and to
keep it spinning. I'm sure that value is not 1 for any fan except one in
a physics textbook (the only place friction does not exist).
Maybe the minimum is index 0 of cooling-levels?
Fan controllers often have a separate value for the lowest cooling level
and for the PWM necessary to start a fan. The pwm associated with the lowest
cooling level may be lower than the pwm necessary to start a fan.
The fan controller would start a fan by applying the "start fan" pwm value
for a period of time, then reduce the pwm to the desired pwm value for
the running fan.
I'll be happy to dig up datasheet references if needed.
Guenter
