I've wondered this too, but is PWM dimming actually changing the current? from what I understood it achieves dimming by turning the module on and off thousands of times per second so that to our perception it appears dimmed. Anybody know if this is correct or something I am misunderstanding?
to my understanding the driver isnt switched directly by a external given pwm signal ( i once thought that too).
there is a logic in front, the 3in1 dimming (detection circuit in the block diagram of the datasheet).
the pwm pfc control logic then will interpret all inputs to corensponding values the driver works with.
in the end it doesnt matter if you dimm by external dimming or by the onboard screws, the internal logic will set it straight for you.
i would guess the control logic set the duty cycle of a internal pwm signal you cant directly influence the freqeuncy, more duration, of but the duty cycle.