TLC 5947: Issues with board over heating

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Dahlia
 
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TLC 5947: Issues with board over heating

Post by Dahlia »

Hi,
After reading the description page on the TLC 5947 it sounds like you can just hook up a 12 VDC external power supply un regulated to the boards directly, but when I did this, the boards get really hot. And after running it through a 12VDC linear regulator the, regulator got extremely hot. After looking closer at the datasheet it says there is a max input voltage of 5V? I am trying to run a total of 210 LEDs that will blink on an off, with a maximum of 87 on at a time. These LEDs are super bright white consumer grade LEDs with an operating current of 16-18mA, 3.2-3.4V. At this point all LEDs turn on and stay on, but the boards get really hot. What do I do?

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Franklin97355
 
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Re: TLC 5947: Issues with board over heating

Post by Franklin97355 »

Could you post clear pictures of your board and the connections to it?
Could you post your code and a description or drawing of your connections between it all?
Please use the code button "</>" when posting code to the forums.

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Dahlia
 
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Re: TLC 5947: Issues with board over heating

Post by Dahlia »

photo (5).JPG
photo (5).JPG (620.75 KiB) Viewed 516 times
:
Here is a photo of the over all project.

Here is a photo showing the arduino nano connections:
currently connected to supply power to the TLC5947 from the arduino board (as a last resort), but this does not work. I have also tried running the power directly from 12V 35AH battery and then through a linear voltage regulator 7812 which outputs 12V at 1.5A. Just spoke with an engineer friend and he thinks that the problem is that since all the LEDs currently light up that I need a regulator that outputs 4A, even though after the program is written, it will only need 1.5A.
photo (2).JPG
photo (2).JPG (703.54 KiB) Viewed 516 times
Here is a photo of the whole wiring box:
photo (3).JPG
photo (3).JPG (753.45 KiB) Viewed 516 times
The DC to DC converter converts the 12VDC down to 5VDC to run the Arduino board.
There are additional wires in pin 8 and the 5V and ground to power a PIR sensor

I have check like a million times that all the LED drivers are hooked up correctly to each other and to the Arduino board.

I have code, but this is not a code problem, it is hardware problem.

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adafruit2
 
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Re: TLC 5947: Issues with board over heating

Post by adafruit2 »

there's an onboard regulator on our breakout

can you draw a simple diagram showing how one LED is connected to a driver board? because if its a single LED in series per output, you should be running the whole thing from 5V, not 12V! if you use 12V @ 0.02A and 24 LEDs, thats an epic 4 *watts* per chip! --> (12V - 3V) * 0.02 * 24

franklin - there TLC's a linear constant-current driver that 'eats' the dropout on chip - see if you can help her get the dropout to less than 1 watt? :)

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Dahlia
 
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Re: TLC 5947: Issues with board over heating

Post by Dahlia »

Each LED is individually addressed. none are in a series.

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Dahlia
 
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Re: TLC 5947: Issues with board over heating

Post by Dahlia »

Also, when I hook up the diasy chain to the 5V output from the Arduino board half the chain does not light up.

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Franklin97355
 
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Re: TLC 5947: Issues with board over heating

Post by Franklin97355 »

Try powering the boards with 5vdc. Did you read and follow this? https://learn.adafruit.com/tlc5947-tlc5 ... r-and-leds especially the bit about removing the connection between v+ and Vin? Also, if you bring the /oe pin high it disables output I'll see if I can tie that high by default on the board.

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Dahlia
 
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Re: TLC 5947: Issues with board over heating

Post by Dahlia »

I have oe set in the setup loop to low and if I power it from 5V off the arduino board less then half the daisy chain gets power ending with the fourth board. The power light on boards 5 through 10 don't even light up. If I use the 12V external power all boards light up and all LEDs turn on, but the boards get very hot to the touch, just shy of burning.

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Franklin97355
 
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Re: TLC 5947: Issues with board over heating

Post by Franklin97355 »

You will need to provide the 5vdc from an external source, not through the Arduino as there is not enough power to do that as you have discovered. We have a 2A and a 10A power supply in the store.

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Dahlia
 
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Re: TLC 5947: Issues with board over heating

Post by Dahlia »

You're the best! Thanks!

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Franklin97355
 
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Re: TLC 5947: Issues with board over heating

Post by Franklin97355 »

Please keep us informed on your progress and perhaps some photos of the front of that project

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Dahlia
 
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Re: TLC 5947: Issues with board over heating

Post by Dahlia »

ok, So I am feeling pretty dumb. I've been staring at this project so long, it's like saying a word over and over again until it doesn't make any sense any more. I have completed more complicated projects so this is a huge blow to my ego. I really wish you guys had a tech hotline so I could call in and suffer this humiliation in private, but here it goes. Done sulking now. I tried a 6V battery to no avail. Went to an 8V and that works, all boards have power. The components heat up but not unreasonably so. Now the last six boards light up and stay on while the first four do nothing. I have checked for conductivity and can not find any shorts. When I tested two chained boards on the breadboard it worked perfectly along with a simple programed routine, but now that everything has been expanded to accommodate 10 boards and soldered into place, nothing seems to work correctly ( i know I should have done a full breadboard and am kicking myself now, but my short deadline, which has come and gone, has influenced bad decisions). Any suggestions on where to start? Am I still having power supply problems (since the power consumption does not seem to equal the math)? I'm running out of ideas and thinking about starting over. I really (really) do not want to start over but will dismantle it if necessary. Desperately yours, D

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Franklin97355
 
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Re: TLC 5947: Issues with board over heating

Post by Franklin97355 »

It's almost impossible to tell from the photos how you are powering and controlling things. Would it be possible for you to draw out the connections between the controller and several of the boards so I could get an idea of where the problem may be? You probably should not be "daisy chaining" the power but running power to each board from the supply using appropriate sized wire. With the drawing we may find the problem.

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