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I have several LED lights (with different driver ICs), several different standalone LED drivers, most of them seem to prefer logic level PWM dimming on their dedicated dim/enable pins. I was wondering can (or would there be any issue) using a single PWM output from an Arduino for multiple drivers?

One of my lights has 3 x PT4115 driver circuits each powering 3 LEDs on a single aluminum PCB. I can change the current sense resistors to lower the constant current, but I was wondering if instead I could take advantage of the PT4115's PWM dimming.

One of the concerns about using PWM on 3 drivers would be unequal dimming/brightness, also not wanting 3 PWM pots for one light, or extra wiring in tight space etc. I was hoping using a single output signal might avoid or limit those issues. I'd also prefer to keep as much of the light and Arduino as standard as possible, and modular for easy change/repair etc.

Is this possible, or is there another way you could suggest?

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  • \$\begingroup\$ Welcome! Depends on the LED light PWM inputs. Do they share ground? If yes, then you probably can. \$\endgroup\$
    – winny
    Commented Dec 20, 2022 at 14:18
  • \$\begingroup\$ It depends on the circuit detail. \$\endgroup\$
    – Andy aka
    Commented Dec 20, 2022 at 14:21
  • \$\begingroup\$ @winny Andy aka I added a photo. It's a 12 or 24v common DC input. \$\endgroup\$
    – FrostyPB
    Commented Dec 20, 2022 at 14:31
  • \$\begingroup\$ 99 % chance it will work but impossible to tell for sure without a schematic. \$\endgroup\$
    – winny
    Commented Dec 20, 2022 at 14:35

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With a common ground it would work with one PWM signal shared between the three drivers. If there was a large difference in the quality of the LEDs then you wouldn't be able to adjust the individual drivers to match, but I doubt it would be a problem unless the LEDs are super old or overheated. You could use one pot but have 3 PWM outputs from the Arduino, and hardcode an adjustment for each output. That way you could still control the unit with one pot, but have the option to fine tune the individual drivers later.

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