This allegro A6833 part is barely available. How do you suppose that works out for people in developing contries?

BTW, some of the prices have dropped since yesterday.

Here's the one listing that seems to have stock.

http://www.newark.com/jsp/searc...CMP=AFC-OP

Have a look at http://octopart.com/search?q=A6833 where the lowest price listed is $3.34 and the lowest available is $6.56

No distributor there seems to offer any sort of "less than a buck" pricing. If you can find one, please share that with all of us.

The same function is attainable by using 10 74HC595's (see http://octopart.com/search?q=74HC595, where one vendor wants only $0.10US for 'em) and a divide-by-80 function to tell 'em to clock their output register, whether in your MCU or external, together with 10 ULN2803A (see http://octopart.com/search?q=ULN2803A) apparently available for $0.25US or less, and a resistor in the '2803's GND pin. It is, after all, only a group of darlingtons with a common emitter, hence, a resistor in the emitter, to GND, will set the current, so long as they're only used one at a time. Now, for approximately $0.35US you have 8 current limited registered outputs SIPO capable of sinking up to 500 mA. That seems to add up to 4.375 cents per column driver. Compare that with the $0.82 per output offered by the available A6833 or the $0.4175 for the less-available part from DigiKey. multiply that cost per output by 160 outputs ... A factor of 10 would certainly give me pause ...

Some of the apparent "confusion" is my fault for foolishly searching for an 8x8 array of LED's that looks the array I've seen/used in the past, but which has a different circuit. The one I used was 64 individual LED's, with 128 pins in a PGA footprint. Each anode, and each cathode was accessible, and that's what I intended to refer to when describing how this "thing" could be done. With the common-row anodes and common-column cathodes, as shown in the device schematic for the array to which I referred, one can't do that. The result is that one has to drive the anodes with a switching transistor capable of sourcing current for all 80, in this case, LED's. Likewise, the only option is to drive the array's cathodes in columns, which rules out other options.

You're certainly correct in that THIS array won't allow individual current limits on each anode. Something has to drive the rows of anodes, though, and I'd guess it would have to be a mosfet or a bipolar of some sort capable of providing considerably more than the 8 Amperes required for the worst-case column (an underline, maybe?)

Your remark, "NO!!! they would drive 1-8 LEDs" regarding the column drive, is probably mistaken, as the 10 2803 collectors would have to drive only one LED, each, at a time, meaning that they'd sink only one cathode at a time, being organized in columns, as only one row of anodes receives supply at a time. Hence, a resistor in the GND pin is really a resistor to GND common to each of the 8 column driver outputs, and therefore would limit the current flowing in whichever emitter was driven by the SIPO output register.

I truly regret my flighty search and acquisition of that Sure Electronics LED array, because I didn't look at its wiring diagram. I was assuming that every anode was accessible, hence a resistor could be attached to each one and those resistors commoned to a row-source driver. That's not possible with this array because all the row connections are common.

RE