[sdiy] LED matrix

[The Old Crow]

  You can use 4051s to select the columns and rows, but the drive current 
for columns/rows will need to be something hefty.  I myself would use 
the venerable UDN2981/ULN2003A current source and sink arrays: source to the 
anodes, sink to the cathodes.  For reasonable brightness a multiplexed LED 
needs a narrow (2ms) pulse of something like 50mA.  Eight of these would 
need 400mA, and 32 of them, 1600mA.  I have a very large led matrix 
display (something like 80x320 LEDs) that uses a 5V at 30A power supply.  It 
uses power transistors in place of darlington arrays, as each column of 80 
must sink 4 amps.  I think the ULN2003 is good for 500mA per section, so 
eight LEDs at full pulse brightness is no problem.

Crow
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On Wed, 28 May 2003, Bert Schiettecatte wrote:

> A totally other question : I'm not an expert on CMOS/TTL IC's, I'd like 
> to use a couple of 4051's to interface a big 32x32 discrete LED matrix 
> to my AVR. Is this possible? Does anyone have a more efficient way of 
> doing this interfacing? I'd like brightness control over each LED 
> (through PWM...?).