Connect with us

The step by step design procedure for AN4143

Discussion in 'Electronic Basics' started by Richard, Jun 29, 2004.

Scroll to continue with content
  1. Richard

    Richard Guest

    http://www.fairchildsemi.com/an/AN/AN-4134.pdf

    http://www.fairchildsemi.com/collateral/AN-4134.xls

    The xls file is to be used with the design steps in the pdf file.

    In the pdf file, I'm getting stuck at : Step (3) (b) RCD reset

    In Excel: You need to choose the Excel sheet "Forward with RCD reset": I
    have a probblem with cell C30. I don't know how to get a value to put into
    cell C30, nor do I know what the parameter is. Cell F30 surely is the
    nominal snubber capacitor voltage, that is, the voltage across the snubber
    capacitor. So, what is the parameter that goes in cell C30? TIA.
     
  2. C30 is the turns ratio between the primary and the reset winding.
    This choice affects both the maximum duty cycle (what fraction of the
    time the primary switch can be on) and the peak switch voltage as a
    multiple of the input bus voltage. 1:1 is pretty normal value. As
    long as you are not trying to squeeze the transformer down to the
    absolute minimum size, this is not terribly critical.
    I don't see any F30 value. There is an E30 that runs over the F30
    cell, but that is the just the minimum limit for the value you can
    type into C30.
     
  3. Richard

    Richard Guest

    John

    You are looking at the wrong sheet. You are looking at the "Forward with
    reset winding sheet" whereas the sheet I'm looking at is the "Forward with
    RCD reset" sheet.

    These Excel sheets are protected, yet I did crack the protection. I don't
    think you need to password though. But if you do I can email it.

    If you reply again, please go over to the other thread that has not got an
    error in the subject line, ie, the thread "The step by step design procedure
    for AN4134" Thanks.
     
  4. Sorry about that. and I thought I had checked your post to get the
    right one.
    Will do.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-