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???
07/04/05 16:07
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#96534 - Not an entirely good idea
Responding to: ???'s previous message
Hi Per,

Depending on the 'raw' input voltage, your proposed solution is not quite the best solution.

While it will keep the average current through the LEDs at a constant and non-destructive level, the peak current will most probably be too high and your backlight will be destroyed anyway (or at least have a severely limited lifespan).

In a lot of my designs I use National Semiconductor SimpleSwitcher ICs as voltage regulator. They are not too expensive and really easy to use.
For what you describe, the LM2672 would be a good choice.
NatSemi also offers an online tool to calculate the design: http://www.national.com/appinfo/power/webench/


Regards,
Rob.

List of 19 messages in thread
TopicAuthorDate
PWM - LCD backlight            01/01/70 00:00      
   One Approach!            01/01/70 00:00      
   Why not.            01/01/70 00:00      
   Not an entirely good idea            01/01/70 00:00      
      But            01/01/70 00:00      
         But but            01/01/70 00:00      
            hmm            01/01/70 00:00      
            Apologies            01/01/70 00:00      
               Buck, actually            01/01/70 00:00      
                  Bugger it.            01/01/70 00:00      
                     Bugger it            01/01/70 00:00      
            Capacitor?            01/01/70 00:00      
               biology            01/01/70 00:00      
   Per            01/01/70 00:00      
      development            01/01/70 00:00      
      I got that working nicely....            01/01/70 00:00      
         Well Done            01/01/70 00:00      
   what I do            01/01/70 00:00      
      final cut            01/01/70 00:00      

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