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???
11/19/07 15:50
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 		 #147192 - This can be deadly!
Responding to: ???'s previous message
Russell said:
first up, I'd get a small 15-40W switchmode psu and remove the 7805 regulator. At least then you should have a fairly clean supply that is immune to brownouts.

This could add even more noise and can be deadly! I wouldn't recommend this, as long as his board is not properly designed to withstand EMI. The 7805 on board is a perfect methode to keep Vcc clean. Farshad could think about powering this 7805 by a pre-switcher though, but not sitting on the same board.

Russell said:
Or use LT1785 chips - beware though as they are slow!

This sounds, as if the LT1785 is a bit bad. I use the LT1785 with great success. Yes, it is slow, but it's made slow by the manufacturer, to highly suppress EMI emissions by controlled slew rates! Just something, that could be very helpful in Farshad's situation. At the same time it provides protection against overvoltages up to +-60V and ESD! This is a very nice chip:

http://www.linear.com/pc/downlo...1713,D2168

Kai

Kai

List of 88 messages in thread
TopicAuthorDate
Atmel 89 Series and EMI            01/01/70 00:00      
   FAQ            01/01/70 00:00      
      Thanks, but...            01/01/70 00:00      
         yes it is            01/01/70 00:00      
            EMI design consideration...            01/01/70 00:00      
               reset pulses?            01/01/70 00:00      
                  Finally a note to the OP            01/01/70 00:00      
                     well, sometimes...            01/01/70 00:00      
                     Fire Extinguisher            01/01/70 00:00      
                        extinguisher            01/01/70 00:00      
                  Latched-up CMOS!            01/01/70 00:00      
                     logic, and beyond            01/01/70 00:00      
                     not a cure            01/01/70 00:00      
   EMI Design            01/01/70 00:00      
      restated in one sentence            01/01/70 00:00      
         Don't jump to the conclusion...            01/01/70 00:00      
            then just say "outside the specs, no can do"            01/01/70 00:00      
      Thanks...            01/01/70 00:00      
   What PCB do you use?            01/01/70 00:00      
      Two Layer            01/01/70 00:00      
         No surprise, then!            01/01/70 00:00      
            Ground...            01/01/70 00:00      
               About naked firefighters...            01/01/70 00:00      
               Absolutely it is fair            01/01/70 00:00      
   Some advice            01/01/70 00:00      
      Yes, it's a bunch of measures...            01/01/70 00:00      
      Good points.            01/01/70 00:00      
         No, no, no,....            01/01/70 00:00      
            Remember            01/01/70 00:00      
         CMOS Latch up            01/01/70 00:00      
         NOPE            01/01/70 00:00      
            You think so...            01/01/70 00:00      
               No, it is not            01/01/70 00:00      
               A proper design would stand it!            01/01/70 00:00      
                  Proper design            01/01/70 00:00      
                     some of my definitions            01/01/70 00:00      
                     Me thinks...            01/01/70 00:00      
                        the real point            01/01/70 00:00      
            More advice            01/01/70 00:00      
               Does that mean, that...            01/01/70 00:00      
                  It's the designers responsibility            01/01/70 00:00      
                     No joke, but...            01/01/70 00:00      
                  EMI and 2 layers            01/01/70 00:00      
                     Yes, for tiny projects...            01/01/70 00:00      
               that something is possible/done succesfully            01/01/70 00:00      
   Show us your design...            01/01/70 00:00      
      Why? You want to make fun of it? :)            01/01/70 00:00      
         Or            01/01/70 00:00      
            You mean...            01/01/70 00:00      
               I do not know what Steve ment            01/01/70 00:00      
               Yes !            01/01/70 00:00      
         how about a schematic            01/01/70 00:00      
            Relays            01/01/70 00:00      
               Even then...            01/01/70 00:00      
         From what I can see            01/01/70 00:00      
            Mostly agree.            01/01/70 00:00      
               Layers, layouts...            01/01/70 00:00      
                  are you serious, or did you forget            01/01/70 00:00      
                     Sorry, I forgot...            01/01/70 00:00      
                     Is it good?            01/01/70 00:00      
                        Just a few points.            01/01/70 00:00      
                           I believe you!            01/01/70 00:00      
                        No harm, usually            01/01/70 00:00      
                  Separate Ground Planes            01/01/70 00:00      
                     Inter-plane coupling            01/01/70 00:00      
                     Cable entry point            01/01/70 00:00      
                        Thanks            01/01/70 00:00      
            what I do ..            01/01/70 00:00      
            half measures            01/01/70 00:00      
            Taking notes...            01/01/70 00:00      
               the downfall of many            01/01/70 00:00      
               Do some tests            01/01/70 00:00      
                  This can be deadly!            01/01/70 00:00      
                     Deadly?            01/01/70 00:00      
                        I'm sorry...            01/01/70 00:00      
         Farshad, I would never make fun of it!            01/01/70 00:00      
            Very Informative            01/01/70 00:00      
               Decoupling            01/01/70 00:00      
                  Thank you!            01/01/70 00:00      
               and not a word about 4 layers            01/01/70 00:00      
   paralelling            01/01/70 00:00      
      Why not using 10µF/10V/X5S ceramics?            01/01/70 00:00      
   more information?            01/01/70 00:00      
      Schematics would not be very "helpfil"            01/01/70 00:00      
      More information            01/01/70 00:00      
      The best stuff I have ever seen is...            01/01/70 00:00      
         Sorry, I forgot, that you must suscribe first...            01/01/70 00:00      
      John, I have seen....            01/01/70 00:00      

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