1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Confusion about how KCL and KVL are used for diode circuits

Tags:
  1. Jan 27, 2017 #1
    1. The problem statement, all variables and given/known data
    Eo5OrNh.png
    This is just one of the example problems in my book which is already solved for me, but I don't really understand their solution which I'll post here:
    They start out with assuming Vin is very negative, which makes D1 turn on and makes Vout=VD,on+Vin. THen they solve for the currents.
    JYPhFsY.png


    2. Relevant equations
    KCL/KVL

    3. The attempt at a solution
    What I am confused on is that if the diode is turned on, then the branch with the diode is a short circuit, so why is there current going in the R2 branch?
    The book solves all the problems like this one the same way, but I don't really get it. Are we assuming the diode is actually on the brink of turning on/off, so it allows current through it, but it's actually not a short circuit yet?
     
  2. jcsd
  3. Jan 27, 2017 #2

    gneill

    User Avatar

    Staff: Mentor

    What does VD.on represent? Is the diode treated as ideal or non-ideal in these problems? :wink:
     
  4. Jan 27, 2017 #3

    cnh1995

    User Avatar
    Homework Helper

    No. You are asked to use the constant voltage model for the diode.
    images (4).jpg
     
  5. Jan 27, 2017 #4
    Oh wow, not sure why I didn't realize it until you guys said it, but now it makes sense, thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Confusion about how KCL and KVL are used for diode circuits
Loading...