Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
Per Westermark
04/04/12 09:08
Read: 803 times
Sweden


 
#187008 - Bandwidth limitation
Responding to: Erik Malund's previous message
In many situations, it can help with a series resisor on digital signals just to slow them down.

Even better is use of EMI filters, since they can reduce the rise/fall times while still have a low DC resistance - in case the load do consume current even in static state.

There is a reason why transceiver chips normally have bandwidth-limitations on the driver pins - with slowed flanks, there will not be as much high-frequency noise transmitted when switching logic state. After all - switching logic state requires current to overcome capacitances. And with a very low resistance, that current can be very high. So generating a strong radiating pulse from the antenna formed by the cable or PCB trace.

List of 36 messages in thread
TopicAuthorDate
FTDI F232RL Noise issues      Raj Nambiar      03/31/12 08:42      
   GND,cables      Stefan KAnev      03/31/12 11:51      
      of this is it, then      Erik Malund      03/31/12 14:19      
   leakage effects..      Jim Granville      03/31/12 16:46      
      Thanks for the comments..      Raj Nambiar      04/01/12 02:02      
         changing the serial port data....      Stefan KAnev      04/01/12 05:11      
         cable, bought off the shelf      Andy Neil      04/01/12 09:00      
            Test standard solutions      Jim Granville      04/01/12 14:54      
               Options..      Raj Nambiar      04/01/12 23:44      
                  VCP /D2X      Stefan KAnev      04/02/12 03:37      
                     Problem exists with both drivers      Raj Nambiar      04/02/12 08:34      
                  Aten serial to USB cable uses a FTDI chip      Kalpak Dabir      04/02/12 04:16      
   FTDI chip ESD sensitivity        Oliver Sedlacek      04/02/12 06:13      
      Thanks Oliver...      Raj Nambiar      04/02/12 08:30      
         Zeners are slow      Erik Malund      04/02/12 08:59      
         show Your circuit      Stefan KAnev      04/02/12 11:04      
            F232 is USB powered but.. + circuit      Raj Nambiar      04/03/12 01:32      
         USB Isolator Chips      Neil Kurzman      04/02/12 21:50      
            Isolators      Raj Nambiar      04/03/12 02:00      
         Better than zeners      Oliver Sedlacek      04/03/12 07:30      
            just a thought      Erik Malund      04/03/12 07:45      
               Layout      Raj Nambiar      04/03/12 22:13      
                  VCP/Direct drivers      Raj Nambiar      04/03/12 23:49      
                  Layout attached      Raj Nambiar      04/04/12 00:51      
                     It's a high speed circuit !!!!      Oliver Sedlacek      04/04/12 05:09      
                        Totally 100% Agreed      Michael Karas      04/04/12 05:34      
                           the trouble with schematics ....      Erik Malund      04/04/12 07:36      
                              Bandwidth limitation      Per Westermark      04/04/12 09:08      
   22 ohms between serial port ground and FT232 ground helps...      Raj Nambiar      04/05/12 23:58      
      of course it does      Erik Malund      04/06/12 08:01      
         Erik,      Raj Nambiar      04/06/12 09:45      
            Links please      Bert Van Den Berg      04/13/12 13:44      
               Link...      Raj Nambiar      04/16/12 00:12      
                  Solved      Raj Nambiar      06/15/12 23:59      
                     Magnetics      Per Westermark      06/16/12 02:08      
                        Ethernet input is connected to serial port ground      Raj Nambiar      06/22/12 08:56      

Back to Subject List