Part Number:DRV8308EVM
We're trying to fine tune the customer fan with DRV8308EVM. However, we are confusing the installation step 5 in the user guide of DRV8308EVM. It says that "a 2.1 x factor is applied to the input duty cycle, 40% duty cycle is treated like 84%" for the 180 SINE commutation control. Why it's not linear control? I meant 10% input duty should have 10% duty cycle output, or 100% input is 100% duty output. what's the purpose?
When the customer fan is controlled with DRV8308EVM and GUI, the max. speed is around 18,000rpm at GUI 60% PWM duty cycle. however, when the PWM duty cycle is increased from 60% to even 70%, 80%,90%, the speed is still around 18,000rpm.
Regards,
Brian