Controlling led strip with 16 SQ2318AES mosfets and pca9685

Other Hardware LEDs and Multiplexing
1

I'm planing to use nano and PCA9685 module to PWM a 16 led strips the design as follow:

  • 12v, 1m LED strip per channel (single color 30LEDs/m, 3LEDs in series)
  • Each channel driven by a MOSFET SQ2318AES
  • 500ohm in series with the gate, and 1kohm for gate discharge.
  • Maybe a clumping diode to protect the MOSFET (not sure if I really need that in this case)
  • 6meters max distance between the strip and the MOSFET board.
  • A big power supply 12v 16.5A 200w for all strips

So my calculation as follow:

  • 20mA per 3 LEDs for 30 LEDs 200mA.
  • power for 1m single color LEDs is 2.4w.
  • Swiping the datasheet left and right wondering what should I check for!!

My questions are:

  • Are the calculations and the design correct?
  • Can this MOSFET do the job?!
  • If not, can we drive the 1m strip using any other SOT-23 package MOSFET.
  • Is there some open source hardware like the requirements.

Thanks.

2

16 strips at 200mA per strip is only 3.2A. Your 16.5A power supply seems overkill.

1K for gate pull-down sounds too low. I would use 10K. This resistor should be attached to the pca output, not the mosfet gate.

Swiping the datasheet left and right wondering what should I check for!!

Wondering why you didn't post a link to that in your post. Have you read the forum guide?

Maybe a clumping diode to protect the MOSFET (not sure if I really need that in this case)

Did you mean "clamping"? If so, not sure why you would want that. Perhaps you are thinking of "flyback" diode? Those are only needed with inductive loads like motors and coils, not with leds.

3

...the resistor value are both randomly selected, my better guess now are in the schematic 100 and 10k ohm.
The MOSFET data sheet link:

The power supply this is what I already have, yes it too overkill
The schematic picture attached below!

2021-01-04_14-28.png

2021-01-04_14-28.png

4

I am not an expert, but the mosfet looks suitable to me. The resistor values are ok also, but see my earlier comment about placement of the 10K resistor.