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???
12/11/08 16:45
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 		 #160860 - What about LED drive current?
Responding to: ???'s previous message
The 4094 doesn't drive much current. Are you sure that it can drive your LED's?

If you buffer the 4094 with transistors or darlington drivers, e.g. ULN2803, etc. There is, of course, the 74HC194, which is also a shift-register. I suspect you can do more with the 'HC164, which is an 8-bit SIPO register capable of driving a modest amount of current (~6mA). You haven't yet mentioned how you intend to operate the 16x80 matrix. Have you considered this?

I'd suggest you review the operation of CRT refresh memory. That will be quite similar to driving the LED matrix, though the LED's can be controlled and timed from your MCU rather than from external logic.

RE

List of 60 messages in thread
TopicAuthorDate
Help Req:Working of 8-bit SIPO Shift Register in LED Display            01/01/70 00:00      
   Look at some datasheets?            01/01/70 00:00      
      Sequence            01/01/70 00:00      
   Could you be more specific?            01/01/70 00:00      
      Got U!            01/01/70 00:00      
         New thread            01/01/70 00:00      
            OK...but            01/01/70 00:00      
               You just proved the point!            01/01/70 00:00      
               Here is a possible solution            01/01/70 00:00      
                  Rash assumption?            01/01/70 00:00      
                     you can use MPUs those has built-in flash            01/01/70 00:00      
                  EPROM with AT89S52            01/01/70 00:00      
               permanent?            01/01/70 00:00      
                  No....            01/01/70 00:00      
                     Non-Volatile Storage            01/01/70 00:00      
                        Still a Problem            01/01/70 00:00      
                           Obviously            01/01/70 00:00      
                              Design work before chip selection            01/01/70 00:00      
         What about LED drive current?            01/01/70 00:00      
            if you plan to multiplex ....            01/01/70 00:00      
               I know you're well versed in this context ...            01/01/70 00:00      
                  Phosphor persistence?            01/01/70 00:00      
                     That's in Erik's primary domain            01/01/70 00:00      
                        Todays LEDs turn on and off very fast            01/01/70 00:00      
                           Intermodulation            01/01/70 00:00      
                              you make some additional points, but            01/01/70 00:00      
                           But what about TV?            01/01/70 00:00      
                              persistence of the tube, I guess            01/01/70 00:00      
                                 Blind test?            01/01/70 00:00      
                                    Problematic test strategy            01/01/70 00:00      
                                       double blind ?            01/01/70 00:00      
                                          Blind tests, revisited            01/01/70 00:00      
                                             I have no such problem            01/01/70 00:00      
                                                For flimmer test too?            01/01/70 00:00      
                                                   done inside and outside            01/01/70 00:00      
                  Interlace            01/01/70 00:00      
                     Not Really            01/01/70 00:00      
               Maybe skip intensity and on-the-fly updates            01/01/70 00:00      
                  They haven not been discussed ... yet            01/01/70 00:00      
                     Forget All...........            01/01/70 00:00      
                        Don't you need a refresh memory?            01/01/70 00:00      
                        Table Lookup is Used            01/01/70 00:00      
                        Need buffering            01/01/70 00:00      
                        that is ridiculous            01/01/70 00:00      
                           character generation            01/01/70 00:00      
                              i think you got me...            01/01/70 00:00      
                                 No tricks involved            01/01/70 00:00      
                                 Here's one way ... but you'll have to code it yourself            01/01/70 00:00      
                                    thanks...i'll try it            01/01/70 00:00      
                                       how to reset HEF4094            01/01/70 00:00      
                                          difference between "strobe" and "output enable" pins?            01/01/70 00:00      
                                          Only be serially writing zeros to it...            01/01/70 00:00      
                                          How are you using the '4094?            01/01/70 00:00      
                                             Not so simple for a newbie...            01/01/70 00:00      
                                                perhaps you're right, Kai            01/01/70 00:00      
                                                   Thanks, but            01/01/70 00:00      
                                                      Did you even read the prior posts?            01/01/70 00:00      
                                                         multiple parallel outputs            01/01/70 00:00      
                                                            actually, yes!            01/01/70 00:00      
   Telephonic discussion            01/01/70 00:00      

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