I need to source 500mA with an AVR

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I know that would kill the chip. I want my AVR to drive 22 LEDs @ 20mA each. Is there some kind of "BUS driver" what can give me 20mA on each output, 160mA total (8 LEDs 1 driver)

thank you ! I have 74HCT541 but it says 6mA max..

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Yes, specifically an LED driver is meant to have a constant current. Maxim and TI make such chips. Just do a search for "led driver" on their web sites and you'll find a variety to choose amongst.

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Allegro has a number of higher current drivers. Some are serial and I think that some are parallel. They tend to be open collector/drain so you can add current limit resistors, etc, as you choose. I believe that they are available from one or more of the common internet distributors (DigiKey, Jameco, Mouser, etc).

Jim

 

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Are "Low Current" LEDs an option for you?
They consume only 2mA instead of 20mA.

Regards
Sebastian

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You could also use a FET. I make a living driving LEDs at 50+amps. hehehe

Go electric!
Happy electric car owner / builder

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What's wrong with a simple transistor? Or, better yet, see ULN2803A. Hook one up to some shift register, and your solution is complete.

edit: Oh, I see, SOURCE was the word. Use a MOSFET. Or similar. Si4435 is small, yet powerful and cheap.

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Thank you all. I'm designing a dot-matrix display. Looks like I will just use a dozen (22) od BC547(NPN bipolar transistor) for each row, and BC639 (simular but 1A) for each column.

By

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Greetings (No Name Supplied),

madid87 wrote:
Thank you all. I'm designing a dot-matrix display. Looks like I will just use a dozen (22) od BC547(NPN bipolar transistor) for each row, and BC639 (simular but 1A) for each column.

This topic comes up quite often on another forum,
there are commercial LED matrices (typically 8x8)
that require drivers and a uC for control.

Please read this thread and this thread and post
your question on that forum (avoids duplication).

Comments Welcome!

--
Peter J. Stonard
www.stonard.com

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Bigglez wrote:

/cut

Thank You, Thank You :)