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There are these RGB & RGBW LED strips with a common anode (V+) input that I want to control.

In the past, I've built circuits around the AL8861Y-13 LED driver IC that can control RGBW LEDS if all the channels had separate anodes and cathodes.

Is there a driver IC that is designed to handle multi-channel LEDs with common anode or cathode? I looked around and can't seem to find one.

If there isn't an IC for it, what's the best circuit layout in controlling these LEDs? Have N-MOSFETs be attached to the cathode of the 4-channels and be PWMed? enter image description here

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  • \$\begingroup\$ Many LED drivers operate in sinking mode. However, most of them use one external resistor to set all the current regulators simultaneously so that might be a problem if your strips are expecting different currents on each channel. There are a few drivers that are designed to power RGB/W LEDs specifically so you might try looking into them. \$\endgroup\$
    – vir
    Commented Jan 19, 2022 at 18:20
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    \$\begingroup\$ Couple of notes: the LED strip you show is a 4-wire RGB, not a 5-wire RGBW. The LED AL8861 driver is intended for series-connected strings of LEDs and drives a constant current through them, while an LED strip like those are strings of parallel connected LEDs each with their own series resistor and should be driven with a constant voltage supply. \$\endgroup\$
    – brhans
    Commented Jan 19, 2022 at 18:56
  • \$\begingroup\$ @brhans I only had the RGB strip on-hand at the moment so I only had that picture available to show but will be receiving the 5-pin RGBW strips soon. If a constant voltage supply should do the trick, then I'm thinking of using a PSU with the rate voltage and power. Then use 4 N-FETS at the 4 sinks and use PWM signals at the gates to control the brightness of the four channels then. I know it wont be as accurate in controlling the brightness as using a constant current flow method. \$\endgroup\$
    – Agriculex
    Commented Jan 19, 2022 at 19:39

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Have N-MOSFETs be attached to the cathode of the 4-channels and be PWMed?

Yes, that is the bog standard way of controlling dumb led strings.

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  • \$\begingroup\$ Is there a "smarter" way to control these multi-channel LED with a common anode? \$\endgroup\$
    – Agriculex
    Commented Jan 20, 2022 at 16:28
  • \$\begingroup\$ @agri the fet does the power control at frequencies that relays won't. They are dc resistive loads so a ssr won't fit. And they are easier to drive than the comparable npn transistor. You are controlling a large parallel load in a single channel. AFAIK these are the best way to handle the power control. Now if you mean smarter as in colors/shades/frequency etc then you can roll your own controller or try to adapt a rgb led controller IC with some logic gates, but they will still need the n-fet for the power side of the equation. \$\endgroup\$
    – Passerby
    Commented Jan 20, 2022 at 16:44
  • \$\begingroup\$ @agri even a non-embedded ws2812 controlling 2 or 3 chips of rgb leds use open drain or open collectors internally. You could use transistor or fet arrays (think uln2003) instead of individual mosfets but that's just packaging. It's still fundamentally the same thing. \$\endgroup\$
    – Passerby
    Commented Jan 20, 2022 at 16:46
  • \$\begingroup\$ okay. Thanks for the info! \$\endgroup\$
    – Agriculex
    Commented Jan 21, 2022 at 15:17

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