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Questions about TLC5947
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Please be positive and constructive with your questions and comments.

Questions about TLC5947

by Jeff1701 on Sun Oct 22, 2017 2:22 am

I'm using a TLC5947 board to drive LEDS in a prop replica I'm building. Each channel will have a single LED, and all 24 channels will be used. Each LED is ~3.0v and 20ma. The board will be powered by 5v 5amp power supply.

I need verification that I am understanding the constant sink resistor correctly.

With the 3.3K ohm resistor built in, the current is limited to 15ma per channel. I need 20ma per channel, so according to the chart on page 13 of the spec sheet I need to solder in a 2.5K ohm resistor. Is this correct?

Must the 3.3K ohm resistor be removed from the board, or will the current flow through the least resistance and the 3.3k ohm resistor can remain?

Thanks!

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Re: Questions about TLC5947

by adafruit_support_bill on Sun Oct 22, 2017 5:31 am

First, the 20mA spec for your LED is a maximum rating. It will work fine and put out plenty of light at 15mA.

If you really need maximum output, can either remove the existing 3.3k and replace it with 2.5K. Or you can leave it in place and solder a 9.1K over it The two resistors in parallel will give you about 2.5K.

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Re: Questions about TLC5947

by Jeff1701 on Sun Nov 19, 2017 9:27 pm

Thanks for the advice. I did solder in a 9.1K ohm resistor is get the full 20ma, and it works great Thanks!

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Re: Questions about TLC5947

by torpedo51 on Sat Nov 25, 2017 8:31 pm

Can you upload a photo of the board after you wired it and added the resistor?

I'm a little unclear how to hookup the LEDs to this...

Thanks

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Re: Questions about TLC5947

by Jeff1701 on Wed Nov 29, 2017 3:48 pm

I can get you a picture later this evening.

Are you going to drive regular LEDs with this board or RGB LEDs?

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Re: Questions about TLC5947

by torpedo51 on Sun Dec 03, 2017 6:14 pm

regular LEDs

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