ADT7470 automatic mode and the PWM is incorrect

Hi, 
I used default settings on my board here, except I'm on channel 2 because the fan on Channel 1 in my board is not populated at the moment, and I'm getting 100% PWM on channel 2 when temp 2 is at TMIN+20C. Are you using the heater control function on the software too?

Regards,
Karen

Hi,

I edited my response to note I used mostly default settings instead of "same". I had on PWMMIN=50. When I set this to 20% like you, it was also around 80%, in my tests PWMMIN has to be at least 40% for PWM going to get to max when temp is TMIN+20. I'll be checking if I can find how this was characterized before, I suspect it was with the default PWMMIN as well.

Regards,

Karen

Hi Karen

Yes, I am using the heater control function on the software too.

Also, no matter what I set my PWM max value(whether is 100 or 30) the pwm will always rise by 3% with a degree increase in temperature. Which I believe means that the slope are the same no matter the PWM max value is. But this doesn't correlate to the datasheet description where "When the temperature reaches TMIN + 20°C, the fans increase in speed to PWMMAX. ". Is my understanding flawed?

Hi Karen

Yes, I am using the heater control function on the software too.

Also, no matter what I set my PWM max value(whether is 100 or 30) the pwm will always rise by 3% with a degree increase in temperature. Which I believe means that the slope are the same no matter the PWM max value is. But this doesn't correlate to the datasheet description where "When the temperature reaches TMIN + 20°C, the fans increase in speed to PWMMAX. ". Is my understanding flawed?