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Topic: using multiple M5451 chips for 500 LEDs (Read 743 times) previous topic - next topic


I need to drive 16  7x5 characters without multiplexing ( so they can be seen in the sun , see photos http://arduino.cc/forum/index.php/topic,135826.30.html )

I fancy trying a M5451 ( 35 outputs )  chip or M5450 ( 34 outputs ) if I can spare one LED in my pattern that makes up the characters.

I would have a HC4515  4to16 line decoder to send an output to each driver latch.

If I use the M5450 I can feed this to the clock enable of each chip,   or for the M5451 which has no clock enable pin, I could apply the data from the micro to the output enable of the 4/16 decoder, to just send data to one chip at  a time.

Digitek and others have quite a stock of these chips at about $2 each.

I dont need to send high speed ( which I would if multiplexing ) as the LEDs are all latched.

There would be an automatic delay between only a few LEDs on,  to all on,  as it would update one character at a time, so no power surge.

I can crank the current up to 18mA according to the data sheet as I will never have all the LEDs on, plus I will keep the LED supply to bare minimum voltage to limit dissipation in the chip.

Has anyone tried this with these chips?

Anyone see anything wrong with the idea?
45 years of editing projects with a knife and soldering iron, then I found Arduino !

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