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

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
01/16/06 06:20
Read: times


 
#107454 - inrush current
Responding to: ???'s previous message
If this was an ac circuit your analysis would be correct. It is a dc circuit. Heavy current flows into the capacitor (limited only by the total circuit impedance and the available voltage) until the capacitor charges. Each cycle sees an exponentialy decreasing current bump until the final steady state current that is the load current is all that is flowing. That low reactance helps keep the ripple at the input to the regulator as low as possible. Normally the reactance of the supply transformer limits the inrush current but care must be taken not to damage the input rectfiers if the transformer has a higher than the rectifier needs kva rating to support other secondary loads.

SMP's use feedback current limiting and much lower load side capacitances due to the high operating frequencys. The input capacitors on line operated smp's are also lower value capacitors but are much higher voltage a rough equivalance is
v1 X c1 = v2 X c2 where
v1 = line voltage c1 = input storage cap v2 output voltage c2 capacitor that would be used if this was a transformer supply for the desired dc output. Terry

List of 56 messages in thread
TopicAuthorDate
Circuit Analysis            01/01/70 00:00      
   Analysis            01/01/70 00:00      
   Dangerous!            01/01/70 00:00      
      bungling amateurs "bragging" on the web            01/01/70 00:00      
         Not electronic, but an amusing example            01/01/70 00:00      
            OLD idea ?            01/01/70 00:00      
               New and improved            01/01/70 00:00      
                  Safety first            01/01/70 00:00      
         I think you meant...            01/01/70 00:00      
         deja vu all over again!            01/01/70 00:00      
      resistor replaced by capacitor            01/01/70 00:00      
         Phase shift            01/01/70 00:00      
         dissapation            01/01/70 00:00      
            Dissipation            01/01/70 00:00      
               It's a real world after all            01/01/70 00:00      
                  What ? Make mistakes ?            01/01/70 00:00      
                     are you sure            01/01/70 00:00      
                     or ..            01/01/70 00:00      
            Non ideal cap performance            01/01/70 00:00      
   Diodes!            01/01/70 00:00      
   Current Limiting Capacitor            01/01/70 00:00      
      Capacitor Filters            01/01/70 00:00      
         Some basic theory needed            01/01/70 00:00      
         12 */~2 ~ 17 so I doubt you see 19V            01/01/70 00:00      
         Output voltage            01/01/70 00:00      
            Regulation            01/01/70 00:00      
            current flow            01/01/70 00:00      
               What current?            01/01/70 00:00      
                  What iam trying to know is            01/01/70 00:00      
                     inrush current            01/01/70 00:00      
                     Naiive analysis            01/01/70 00:00      
                        Laplace Transformation            01/01/70 00:00      
                           Could be worse....            01/01/70 00:00      
                              Me too!            01/01/70 00:00      
                                 Minds are failing            01/01/70 00:00      
                     DC component            01/01/70 00:00      
                        Suresh, have as look            01/01/70 00:00      
                           analog and digital ground            01/01/70 00:00      
                              discussed ad nauseam do a search            01/01/70 00:00      
                              Use a splitted ground plane            01/01/70 00:00      
                                 did i got it right            01/01/70 00:00      
                                    Also datasheet of ADUC can help you            01/01/70 00:00      
                                       Placing Vias            01/01/70 00:00      
                                          Maybe..            01/01/70 00:00      
                                             Copper fills            01/01/70 00:00      
                                          I do not know about 2 layers            01/01/70 00:00      
                                        Auto route            01/01/70 00:00      
                                          Solid ground plane has to be solid!            01/01/70 00:00      
                                             Thank you Kai            01/01/70 00:00      
                                                circuit for a despensing unit            01/01/70 00:00      
                                                   ICM7555 + 2M2 + 6ยต8            01/01/70 00:00      
                                                      why a totally unrelated post in the midd            01/01/70 00:00      
                              Separate signal traces.            01/01/70 00:00      
                                 What has God to do with this??            01/01/70 00:00      
               DC DC            01/01/70 00:00      
               DC DC            01/01/70 00:00      

Back to Subject List