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???
02/21/07 09:25
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 		 #133400 - mux vs. pulsed
Responding to: ???'s previous message
Chris Kelly said:
What I am adamant about, however, is that multiplexing/reduced duty cycle is useful for more than just "saving ICs".


What Erik tries to say (among others) is, that there are reasons NOT to use multiplexing beyond the possible troubles with high current pulsed mode of operation.

These are two things - multiplexing and pulsed operation - which can and maybe should be distinguished. Of course, you cannot operate a multiplexed display without pulsed operation, but you CAN pulse a non-multiplexed display, if needed...

Jan Waclawek

PS. There actually are LEDs which light output increases with current faster than linearly - aka superLEDs. Basically they are semiconductor lasers with deliberately or accidentally imperfect resonator (mirrors), and this effect is the result of - possibly more efficient - stimulated emission, starting to prevail above a certain threshold. However, this certainly is NOT the case of the common cheap LEDs.


List of 43 messages in thread
TopicAuthorDate
Components for Outdoor LED Display            01/01/70 00:00      
   What are the specs?            01/01/70 00:00      
   you are already scewed            01/01/70 00:00      
      any better suggestions?            01/01/70 00:00      
         are your LEDs capable of 200mA ?            01/01/70 00:00      
            Human eye perception            01/01/70 00:00      
               percieved does not matter            01/01/70 00:00      
                  Perception is everything            01/01/70 00:00      
               LEDs are extremely nonlinear, too!            01/01/70 00:00      
                  I covered this            01/01/70 00:00      
                     I wrote -extremely non-linear-...            01/01/70 00:00      
                     that makes no sense            01/01/70 00:00      
                        Example with LTJ-811            01/01/70 00:00      
                           let the sunshine in            01/01/70 00:00      
                              LEDs appear the same in all conditions            01/01/70 00:00      
                                 Err            01/01/70 00:00      
                                    actually we have one multiplexed, however            01/01/70 00:00      
                                    King of LEDS :)            01/01/70 00:00      
                                 mux vs. pulsed            01/01/70 00:00      
                                    better ask ERIK ...            01/01/70 00:00      
                                       well, this is not so 'new'            01/01/70 00:00      
                                       more bright than outdoor....            01/01/70 00:00      
   why I want to multiplex            01/01/70 00:00      
      assumption?            01/01/70 00:00      
         the way multiplexing works            01/01/70 00:00      
            what is required?            01/01/70 00:00      
               Requirements are what you should analyze            01/01/70 00:00      
                  Backwards?            01/01/70 00:00      
                     low-side cap, low-side NPN            01/01/70 00:00      
                        One-bit memory == DC filter ???            01/01/70 00:00      
                           slow decay            01/01/70 00:00      
                              you can have NONE            01/01/70 00:00      
                                 are you sure?            01/01/70 00:00      
                                    yes, I am, yes I have            01/01/70 00:00      
                                 I agree with Erik ... at least somewhat            01/01/70 00:00      
                                    I am still CURIOUS            01/01/70 00:00      
                                       it's like a camera flash            01/01/70 00:00      
      already answered http://www.8052.com/forum/read.ph            01/01/70 00:00      
         Averages            01/01/70 00:00      
   does the A6278 LED driver multiplex too?            01/01/70 00:00      
      if you want to make a nonmultiplexed display...            01/01/70 00:00      
         that clears up a lot            01/01/70 00:00      
            sorry            01/01/70 00:00      

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