I temporary got a MacBook Air M2 13'' and decided to measure possible PWM.

The results surprised me. In the range of 8-12 brightness bars there is a noticable flickering at ~60 Hz.

In the range 0-8 and 12-16 bars there is no such flickering.

At the same time I measured PWM on the MBP 15 2019 and didn't find something.

The measurements were done by an oscilloscope.

Do someone have an idea what is it?

ADDED: I suspect it can be a refresh rate of the graphic card to save more power. Using duty equal to 50% can help to save the power consumed by the graphic card close to the 50% (at least responsible for the framebuffer power).

The interesting thing is this flickering cannot be detected by the 240 fps camera due to relatively low magnitude of flickering.

    NewDwarf Do someone have an idea what is it?

    We need more measurments, for analysis

        simplex it is exactly the same for all steps where flickering is present. Same magnitude and the same duty.

          I haven’t had the opportunity to test any M series MacBooks yet but the intel version I tested had a very low amplitude of flicker according to my meter. I wonder if that’s the reason you may have issues detecting something at certain brightness levels.

          NewDwarf The fact that it is refresh rate equal to screen image refresh rate is interesting. Now add the fact that these MacBooks are strsiny on good screens and tests confirmed (over HDMI) is also very interesting. We are getting somewhere.

            dev