How should I proceed with the design of this RGB LED and what does this wiring diagram imply?

I haven't made a design with RGBs before, so the wiring diagram from the RGB Datasheet puzzles me. My immediate thoughts are as shown in the attached schematic.

Don't mind the transistor specs and resistor values (just needed the footprint) I would also like to implement a load switch between VCC and COM+ and some pulldowns for the transistors, depending on the MCU

(Wiring diagram)

From datasheet



  • 3
    \$\begingroup\$ Those body diodes will light your LEDs up all the time. In any case, better to put the source to ground and have the resistor between the MOSFET and the LED so the gate-source voltage isn't reduced by the voltage across the resistor. \$\endgroup\$ – Finbarr Nov 1 '19 at 9:19
  • \$\begingroup\$ True, I was just thinking about that as I reread the post :) \$\endgroup\$ – Sorenp Nov 1 '19 at 9:20

You appear to be using P-channel MOSFETs to do low-side switching which is an odd choice due to the more complex gate driving arrangement that would be required. On top of this you won't be able to turn off the load.

You'd be better off with N-channel MOSFETs for switching loads to ground, the gate driving is very simple if you use logic level MOSFETs and not much more complicated if you don't. The body diode will also not allow the LEDs to light all the time as it'll be reverse biased when the FET is turned off.

EDIT: I would also move the resistors so they are between the LEDs and the MOSFETs and the source of the MOSFETs is directly connected to ground.

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