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?