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Topic: Problem with multiple tlc5940 (Read 8 times) previous topic - next topic

Grumpy_Mike

They are in the right place but you seem to have taken off the 0.1uF ceramic caps you had on earlier, why?
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Dcoupling might not fix a wiring problem, but it still is needed. The layout is a bit messy but then I never did like solderless bread boards anyway.

Try as a temporary measure reducing the TLCs drive current to see if you have a power supply issue.

quizz_kid

I added the 0.1uFs, and still no change. Hmm...

How do I reduce the drive current on the tlc?

Hippynerd

Im not sure by your picture, but I think you may have the 47 cap on it wrong. I think you want positive lead on the chip, and the negative lead on the ground of of chip, or the ground rail.

by reducing the load, I think what he means is change the resistor that sets the current level for the LEDs. I think its 2k in the demo for 20ma, If you change that to 4k, it I think that will set if for about 10ma.

Grumpy_Mike

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Im not sure by your picture, but I think you may have the 47 cap on it wrong. I think you want positive lead on the chip, and the negative lead on the ground of of chip, or the ground rail.

No you have the cap on pin 22 which is where it should be.

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think its 2k in the demo for 20ma, If you change that to 4k, it I think that will set if for about 10ma.

Yes that is right.

quizz_kid

I cant seem to find a 4k resistor anywhere... Does it have to be 4Kohm?

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