Go Down

Topic: TLC5940 Overheating (Daisy Chain) ( Electronic Beer Pong Table) (Read 5 times) previous topic - next topic

saeveritt

Nov 03, 2011, 04:15 am Last Edit: Nov 03, 2011, 07:09 am by saeveritt Reason: 1
Ok, well currently I am at (5 x .06) + (5 x .02 x 16) = 1.9, which is under the limit of power dissipation.
My setup is:


I just pulled out the 10k pull-up resistor. Mainly because I was getting fed up with all of my fried chips. (4 of them!)

It seems to only be the first one taking the damage, it is getting super hot! Does anyone have any suggestions?

12v into Mega's Vin, 5v and 2A for the RGB led's common annode, 5v from arduino to power tlc's

Here is what I have so far:
http://www.youtube.com/watch?v=plQjQ_RiNaA&list=HL1320291567&feature=mh_lolz

I'm currently running on a Mega

Mega pin 51 (MOSI) -> SIN (Tlc pin 26)
Mega pin 52 (SCK) -> SCLK (Tlc pin 25)
Mega pin 11 (OC1A) -> XLAT (Tlc pin 24)
Mega pin 12 (OC1B) -> BLANK (Tlc pin 23)
Mega pin 9 (OC2B) -> GSCLK (Tlc pin 18)


LED Datasheet: https://docs.google.com/open?id=1vwge5JS-4A-AJEv53ObcY4Knkq1JKmPyuO3D0Z3LMx2U6tL-tSeY2NN-7sdY

Chagrin


Cranium

Nice start for your project.  I see where your priorities are though.   XD

When I was working on my RGB LED Stairs Illumination project with 6 TLC5940s to drive 30RGB LEDs, I initially had some overheating issues as well (fried two TLC5940s) but was able to overcome them after doing a tear down of my breadboard and setting it back up along with adding some additional jumpers across the power rails.  I'm powering mine with a L7805CV (5v 1.5A) regulator with heatsinks added and a 7.5V 3A wall wart.  When I started with a 12V wall wart, the VR would overheat.  My power with the illumination routines I run peaks at about 1.4A which is too close to the max for my comfort and the VR is only barely getting warm but I'm still going to change it.  I have an external 5V 3A power supply that I've tested on my bread board setup running all 30 RGB LEDs at full brightness (~1.8A) for an hour and it worked wonderfully.  The TLC5940s barely got warm while each was supplying 300mA to the LEDs.

1.9A is too close to the 2A capability of supply power.  Your arduino needs power as well as the TLC5940s to run.  You may be dropping voltage down too much with a struggling VR.  Is it getting hot?  If so, do you have heat sinks on it?  Have you measured the measured the max current of the entire circuit?  Are the fans drawing power from the 5V 2A power as well?  What is the rating of the 12V source you mentioned?

saeveritt

Thanks for the quick replies!



1.9A is too close to the 2A capability of supply power.  Your arduino needs power as well as the TLC5940s to run.  You may be dropping voltage down too much with a struggling VR.  Is it getting hot?  If so, do you have heat sinks on it?  Have you measured the measured the max current of the entire circuit?  Are the fans drawing power from the 5V 2A power as well?  What is the rating of the 12V source you mentioned?


5v 2A is powering just the 20 RGB led's across the anodes. (60 Led's running at 20mA each)

My arduino is powered by 12v into the Vin. The rating of the 12v source is  5A and 60W. (Also powering my fans)
the second 5v power supply is from the arduino's 5v. This is for the Tlc5940's.


Where is the "5V and 2A" for the LEDs supplied from?


From a wall wart, it's completely separated from the other power supply.

Cranium


5v 2A is powering just the 20 RGB led's across the anodes. (60 Led's running at 20mA each)

My arduino is powered by 12v into the Vin. The rating of the 12v source is  5A and 60W. (Also powering my fans)
the second 5v power supply is from the arduino's 5v. This is for the Tlc5940's.


Now I have a better picture of what you were trying to explain.  :)

From the looks of things, I can see nothing wrong with the schematic.  When I fried the two TLC5940s, it was also the first in line now that I'm thinking about it.  I think mine was a loose/bad connection.  Any flickering of the LEDs?

Go Up