Hello expert,
For PWM control Vref, is there any concern about its’ applied PWM frequency range? (which is related to RC time constant setting(<200ns))
What’s the concern about setting for less than 200ns time constant?
Best regards,
Ann Lien
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Hello expert,
For PWM control Vref, is there any concern about its’ applied PWM frequency range? (which is related to RC time constant setting(<200ns))
What’s the concern about setting for less than 200ns time constant?
Best regards,
Ann Lien
Ann,
I sent 2nd request to system/design team yesterday. But, not get the answer yet.
But, I pretty much sure, the low pass filter time constant should be longer than 200ns. if less than 200ns, we don't need to add that capacitor and cannot call it as a low pass filter.
If we don't have a low pass filter, VREF pin could get a rectangle waveform which could affect the motor driver current regulation.
For the RC time constant, I would think it should be few time longer than the longest PWM cycle time. If we assume PWM frequency is 20kHz. The cycle time is about 50us. I would like customers put the RC filter time constant longer than 200us.
Ann,
I cannot recall the deleted post. Let me reply again.
" RC-time constant is better to be spaced by 5x to 10x of Generally PWM-period. (you mentioned by 4x. That is decent)"
If the PWM cycle time is 50us, please ask customer to use 250us or longer time constant filter.