I am using Cree RGBW LED's 700ma per die in a project. I have a question on the voltage necessary to fully turn on the top two mosfets in the chip.
I have used a diode to drop the voltage feeding the LED's so that the gates G1,G2,G3,G4 can be driven by four pins on a uC. Bread boarding the design it works fine. The question is from the data sheet, how do I calculate the voltage necessary to drive gates G4 and G3. Is 1 diode drop going to be enough to fully turn on those two mosfets?
Would it be the Gate to source voltage threshold minimum of 1VDC so I should perhaps use two diode drops at .6V to make it 1.2VDC drop? The resistors are going to be under 1 ohm for three of the dies on the LED and the top two mosfets will be driving the 3.9VDC forward voltage led dies.
Note. One of the colors (RED) has a forward voltage of just 2.5 so an additional resistor will be used to connect to ground, not shown on schematic.