TLC5940 with separate power to the LEDs question

Forum 2005-2010 (read only) Hardware Interfacing
1

I want to use a powered USB hub to connect an Arduino Nano to my computer. The Nano will be controlling a circuit that consists of 3 TLC5940's and 16 RGB LEDs. I want to have the max current of 20ma available to each color of each LED.

My problem is (if I'm doing my math right) that I'd need to provide a total of 16320mA = 960ma of power to the anodes of the LEDs. Therefore, that tells me I can't source the LEDs off of the Arduino's 5V output.

So, to my question... Since my powered USB hub gets it's power from a 5V 3A DC power supply, can I tap the 5V for the anodes of the LEDs off of this power supply at the point where it enters the USB hub?

Thanks,
lqbert

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Probably. But it is rather an unconventional kludge. It assumes that the ground from the USB hub power input connects through to the ground in the USB cable. That is probably a safe assumption, but I wouldn't bet my life on it.

Thanks for the reply... would I be able to tell this if I just check the voltage between the ground of the Arduino and the ground connection on the USB hub power supply (reading of 0V)???

Would you, or anyone else, have any suggestions for my a "proper" way to accomplish what I'm after?

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have any suggestions for my a "proper" way to accomplish what I'm after?

Simply make a splitter to tap off the power before it goes into the hub and use that to power the LED anodes.

4

Grumpy_Mike:

Simply make a splitter to tap off the power before it goes into the hub and use that to power the LED anodes.

I was hoping it would be that easy!! Awesome, I'll try this once I receive all my parts.

lqbert