>Werner Terreblanche <wterreb@PLESSEY.CO.ZA> wrote:
>>   I used to make LED displays like the one you describe.  Mine worked
>> as follows:
>>
>> I used a row of 74HC164 shift registers, all connected in series so
>> that whatever you clock in at the first one, would eventually get to the
>> last one.  Then every shift register was buffered by a ULN2803
>> driver.   If your display is 96 leds wide, then you will need 12 x
>> 74HC164's and 12 x ULN2803's.   There will also be 96 resistors to
>> limit the current to the LED's.
>

Eric Smith said:
>Note that Allegro (formerly Sprague) and other vendors of analog driver chips
>such as the ULN2803 also make driver chips with integral shift registers.  I
>don't have any part numbers handy, but I've used them in the past.  They
>reduce package count, but I'm not sure whether or how much they reduce the
>parts cost.
>
They can. The Allegro 5810 thru 5818 are serial drivers from 10 to 32 bits.
They can be cascaded. All outputs can simultaneously sink 25 ma and still
stay within total package dissipation limits. On the design where I used it
a year or so ago, the 5812 (20 bits) was USD $2.58 in qty 100.


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