Connect with us

Help debug DC/DC buck converter

Discussion in 'General Electronics Discussion' started by saroz, Apr 1, 2014.

Scroll to continue with content
  1. saroz

    saroz

    8
    0
    Apr 1, 2014
    Hi,
    This is the schematic and just today we got our board and after soldering the buck converter(ADP2370-3.0V) I was surprised to see 1.6v across the capacitor (C1) while I was supplying clean 6.0V DC. Soldering was done in a lab with the professional. The mistakes we think could be whether the connection of the respective pins of the regulator are correct. Any help would be much appreciated. Thank you.
     

    Attached Files:

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,993
    2,500
    Nov 17, 2011
    What type is IC1?

    I think there's at least one error: C1 needs to be at the output after D2.
     
  3. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    show us a pic of your construction so we can check your wiring

    Dave
     
  4. saroz

    saroz

    8
    0
    Apr 1, 2014
    IC1 is the dc/dc buck converter 3.0v fixed output. C1 is the output capacitor and the Diode is used for reverse current discharge protection.
     
  5. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    Harald
    he listed the IC as a ADP2370-3.0V

    going by the datasheet he seems to have his circuit OK ... doesn't really need the diode tho


    Dave
     
    Last edited: Apr 1, 2014
  6. saroz

    saroz

    8
    0
    Apr 1, 2014
    Hi davenn, let me post the whole circuit.
     

    Attached Files:

  7. saroz

    saroz

    8
    0
    Apr 1, 2014
    Pic of the board ?
     
  8. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    yes ... so we can check your wiring
     
  9. saroz

    saroz

    8
    0
    Apr 1, 2014
    I have attached the board layout and the board pic itself.
     
    Last edited: Apr 3, 2014
  10. Harald Kapp

    Harald Kapp Moderator Moderator

    10,993
    2,500
    Nov 17, 2011
    Sorry, I didn't match the text with the schematic. You're absolutely right.

    Harald
     
  11. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    How big are your super caps? They might be loading the output?
    Adam
     
  12. saroz

    saroz

    8
    0
    Apr 1, 2014
    I haven't connected them yet. Just supplying the 6V Dc and checking voltage across C1.
     
  13. saroz

    saroz

    8
    0
    Apr 1, 2014
    So, here is the result. We disconnected D2 and we got the perfect 3.0V out across C1 .Meaning the buck converter works. And when we connected the diode back again , the result was back to 1.3V out .

    Here is the other interesting thing though, we were getting 7V across the diode, kinda amplifying. When we desolder the diode and shorted with wire, everything worked perfect. Whenever we connect diode the problem comes back.

    The only reason to use that diode is to prevent the reverse current discharge from Super Caps to the solar panel and drop the voltage to 2.5 for the supercap rating of 2.7V. Now we are thinking of getting rid of it altogether as we read in the datasheet of ADP2370, it prevents the reverse current flow.
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,473
    2,819
    Jan 21, 2010
    Got a scope?

    Put the diode back in, add a small load resistor (10k?), then look at the signal on each side of the diode.

    You might get more of an understanding of what is going on.
     
  15. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    Yeah think I see where Steve's going. The diode is rectifying the noise from the coil and charging up the capacitance of the circuit which is why a small load is going to show this up.
    Adam
     
  16. saroz

    saroz

    8
    0
    Apr 1, 2014
    Thanks a lot for your guys help. Everything is working fine now. I had few other boards coming in today and it all worked as expected. I think in the first board that I was testing some solder problem might have happened.
     
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

-