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

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
09/15/06 23:29
Read: times


 		 #124386 - Various loads
Responding to: ???'s previous message
When you take a Cat5 cable for your RS485 loop, showing a characteristic impedance of 100 Ohm, then you need two 100 Ohm termination resistors at both ends, which gives a load impedance of 50 Ohm. Differential driver output voltage at this load is about 2.5V, resulting in an additional supply current of 2.5V / 50 Ohm = 50mA, which is about ten times the idle supply current of a RS485 transciever without load!

Kai

List of 49 messages in thread
TopicAuthorDate
Getting Power from PC RS232?            01/01/70 00:00      
   maybe            01/01/70 00:00      
      USB?            01/01/70 00:00      
   Serial port power links            01/01/70 00:00      
      the most abused "design criteria"            01/01/70 00:00      
   This circuit usually works            01/01/70 00:00      
      Kai, you disappoint me            01/01/70 00:00      
         I'm not here to amuse you...            01/01/70 00:00      
            no amusement seen            01/01/70 00:00      
      More pin options            01/01/70 00:00      
         A couple of questions            01/01/70 00:00      
      just a note...            01/01/70 00:00      
         Not so simple...            01/01/70 00:00      
            rs232 to rs485            01/01/70 00:00      
               Why not USB?            01/01/70 00:00      
                  usb?            01/01/70 00:00      
                     See reply to your duplicate post            01/01/70 00:00      
                     You need to specify better what you want.            01/01/70 00:00      
               you should have had a look            01/01/70 00:00      
                  You can, but...            01/01/70 00:00      
                  it has to drive 5 volts into 100 ohms            01/01/70 00:00      
                     Various loads            01/01/70 00:00      
   serial mice have been doing this for years, but...            01/01/70 00:00      
      These schemes work despite deviations from standar            01/01/70 00:00      
         Pins 9 & 10 on DB25            01/01/70 00:00      
            For the record, RS 232 power is a bad idea.            01/01/70 00:00      
               commercial device powered by RS232            01/01/70 00:00      
                  definitions and opiunions            01/01/70 00:00      
   usb            01/01/70 00:00      
      More Info Required            01/01/70 00:00      
      standard "USB port" response            01/01/70 00:00      
         You really don't want to do that            01/01/70 00:00      
            USB only hurts the first time            01/01/70 00:00      
            COMx: vs USB            01/01/70 00:00      
               Acronyms            01/01/70 00:00      
                  silly game!            01/01/70 00:00      
                     More Silly Game, SMSers should like this.            01/01/70 00:00      
                        did you fo to the Bean Pot            01/01/70 00:00      
                           It's been around awhile            01/01/70 00:00      
               is that Arizona, Mars            01/01/70 00:00      
   usb?            01/01/70 00:00      
      I don't think so...            01/01/70 00:00      
         SiLabs            01/01/70 00:00      
      oy            01/01/70 00:00      
         Cost?            01/01/70 00:00      
            Budget            01/01/70 00:00      
               cost?            01/01/70 00:00      
                  Cost!            01/01/70 00:00      
                     it has 2 slaves as well            01/01/70 00:00      

Back to Subject List