I'm in the process of designing a LED strip driver using a WS2811 chip and 3 MOSFETs. I've attached the schematic below. I based it on the reference circuit in the WS2811 datasheet (link), and this breakout board from Freetronics (link to schematic). I think I'm on the right track with my design, but I had a few questions before I go ahead and order parts.

  1. I have selected the BSS138 MOSFET to drive the NTD4806NG MOSFET which will drive the LEDs. Is the BSS138 actually needed for the MOSFETs I have selected? I read over the datasheet for the NTD4806 and it looks like it might be ok at a 5v logic level, but a lot of the WS2811 MOSFET drivers I've seen included the smaller MOSFETs.

  2. Are N-Channel MOSFETs the right choice to go with the WS2811? Or should I be using a P-Channel MOSFETs circuit. I've seen a few other people build similar circuits both ways - why might I favour one over the other?

  3. Can anyone spot any other "gotchas" with my design that I might be missing?

Thanks for all the help!

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  • \$\begingroup\$ Welcome to EE.SE. It is not good to have such high value (10K) pull-up resistors on the MOSFET gates. It will result in a poor (slow) rise time and have the MOSFET in a linear region for some microseconds. It translates to extra heat. Try to keep them under 1K if possible, and as low as 150 ohms if possible. That would give you a fast rise (ON) time for the LEDs. It will avoid 'bleeding colors' as well. \$\endgroup\$ – Sparky256 Feb 25 at 4:18

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