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Topic: 6x TLC5940 32 rgb leds (Read 10 times) previous topic - next topic

Krolo

The chips seem to do just fine as long as I plug them in the right order with no heat.

I have a bunch of 3w rgb leds with 350ma per led and a HengFu with two 20amp 5v outputs. The r3 resistor I used a 1.5ohm 2watt. I planned on providing 20amps 5v per board which I think should be ok but I don't think my multimeter can handle that kind of current to actually test it to see how much it's pulling. I plan on having up to 6 boards per art piece. While I think it should work i'm not sure if its the best practice. From my understanding I could have a higher voltage power supply for V2  and the extra voltage will just get burned up in the FET. Would that be a better option, or would it just be less efficient?

Grumpy_Mike

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The chips seem to do just fine as long as I plug them in the right order with no heat

Never ever plug in a chip when the power is on. It is the best way to destroy them.

Krolo

Ok so I have six of these boards done for a total of 96 outputs. I have tested each of these individually ok. I have hooked it up just as before except a separate power connection for vcc for the chip.

I power on all the chips, wait a few min and they are all fine and cool to touch.

I plug in the arduino that has a different power source with a shared ground and 3 of the chips fry.

So I'm not sure if a wire has came loose in my temporary setup or how to hook this up without frying the chips.

I know they are fried because I hook them up again with only vcc and ground and they are extremly hot.

I can replace the chip, hookup the arduino directly to  the board instead of a breakout boards of greyscale clock, blank, etc and the board works ok. I know you said that working with higher powered stuff complicates things but this seems more like a hookup issue than a decoupling issue.

Feel free to ask questions, I feel like this can work but i'm just missing something simple.

Grumpy_Mike

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I power on all the chips, wait a few min and they are all fine and cool to touch.

This is because they are not doing anything so no heat is generated.

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I plug in the arduino that has a different power source with a shared ground and 3 of the chips fry.

Is the code that drives the LEDs running at this point. You should not plug in circuits together with the power attached. Connect it all up and apply the power.

Krolo

There are three voltage sources. The 5v that powers the chips only, the 5v that powers the output circuits, and the arduino 12v. I'm not sure why it fry's some of the chips while it should work. 50x chips just arrived in the mail, I guess I just have to play around with it.

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