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I am trying to build an extra powerful programmable RGB array, and I have chosen the ws2811 chip.
It came with this diagram for working with higher currents, but I am unable to determine the value of resistors. R3,4,5. it says it's 5kohm but it doesn't seem to work by my calculations.
FYI, the chip takes in 0-18.5ma as a output, but my LEDs need 300ma, so I have to use a transistor. my theory is that if R2 is 5kohm, then the voltage at the base of the transistor will be negative when the chip is driving 18.5ma.
edit: might be the max rated constant current is 18.5, any value less than this, the terminal voltage will be zero. But I still don't get the full range of the chip
This topic was modified 3 years ago by Tim
Posted : 28/04/2022 8:35 am
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update: I have managed to squeeze all this onto a PCB. Each module, 10 by 10 centimeters in size, has 16 units, each around 10 watts.By my calculations, it's going to throw out 150w of heat per module.
Is there any tip to cool it down properly?
p.s. I wish to mount the modules side by side to form a bigger array. so using a huge PC heatsink is not ideal because it sticks out at the sides
Posted : 30/04/2022 1:55 pm