Hello,
Is it true that the frequency spectra of the CXA3050 LED will be the same whether it is PWM dimmed or Analog dimmed?…
All bare LEDs are monochromatic, in other words they emit only a single specific colour clustered around a specific single wavelength.
White light is made up of a wide spectrum containing many colours, so a LED cannot do that all by itself.
The way white LEDs work, is that an ultraviolet LED irradiates a white phosphor which creates the visible light. The LED can only produce light in the ultraviolet region, about 450nM.
Fluorescent tubes work in the exact same way.
No matter how you drive that LED, it can only produce energy at 450nM anyway.
So nothing changes between driving it with dc or pulsing it with PWM.
The characteristics of the phospor are something else. This does change over time and different batches of LEDs, or LEDs from different manufacturers.
But dimming, either by analog or digitally will not look any different provided the PWM is fast enough to avoid flicker, which is not all that fast.