We use the custom carrier board , about the fan circuit, refer to the P3768.but we find that the fan tach does not become quickly when the temperature become higher
Are you using same setting with devkit? You can probe the signal and compare to devkit to check if PWM is changed.
We have not the p3768 devkit and cannot to compare
There is no update from you for a period, assuming this is not an issue any more.
Hence we are closing this topic. If need further support, please open a new one.
Have you checked the pwm value when temperature goes high? Does it really stay low?