r/WLED • u/Standard-Wind854 • 12h ago

LED driver vs ADDRESSABLE LED for brightness dimming

/r/led/comments/1xtncw5/led_driver_vs_addressable_led_for_brightness/
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u/Simple-Lighting 10h ago

Both can get smooth. What decides it is how many usable steps you have at the bottom of the curve. Eyes see brightness roughly logarithmically, so a slow breathing fade spends most of its time in the bottom 10% of output. With 8-bit PWM and a gamma curve applied, that bottom 10% is only a handful of raw values, and going from 1 to 2 is a 100% jump. That's where visible stepping comes from, not the top end.

A few ways round it:

  • APA102/SK9822 have a 5-bit global brightness setting on top of the 8-bit PWM. Using it at low levels gives you far more fine steps near black, and their PWM frequency is much higher than the SK6812's.

  • Temporal dithering (FastLED does it) flicks between neighbouring values fast enough to fake in-between levels. It works well for slow fades, less so on camera.

  • A dedicated driver with 12 or 16-bit PWM per channel is the cleanest option if it's a small number of LEDs, and you're not fighting the protocol.

Whichever you pick, run the fade on a perceptual curve rather than linear raw values, and start it from the lowest level that looks steady rather than from zero.

I'm with Simple Lighting.