Results 1 to 7 of 7

Thread: Is possible to get 12v/10amp, 3.3v/10amp, 5v/10amp from LM2678 chips?

  1. 09-07-2005, 07:56 PM #1
    jvinis
    jvinis is offline
    Newbie
    Join Date
    Sep 2005
    Posts
    5

    Is possible to get 12v/10amp, 3.3v/10amp, 5v/10amp from LM2678 chips?

    Hi all !!

    First of all in not a Electronics Expert but one person with basic knowledge of analog electronics.

    I have found the LM2678 chip interest for dc-dc PSU and i have some questions to Sproggy and Mastero gurus.

    Is possible to get 12v/10amp from 2 x LM2678-12 chips in parallel instead of 1 x LM1084IT-12 chip and 1 x LM2587T-ADJ chip (MASTERO 4.5 design)
    and 3.3v/10amp from 2 x LM2678-3.3 chips in parallel instead of 2 x MAX788 chips (MASTERO 4.5 design)
    and 5v/10amp from 2 x LM2678-5 chips in parallel instead of 2 x MAX787 chips (MASTERO 4.5 design)

    Is something wrong with the Typical Application Diagram from LM2678 ?

    Have someone tried this design ?

    Thanks.

    Reply With Quote Reply With Quote
  2. 09-08-2005, 01:14 AM #2
    rushnrockt
    rushnrockt is offline
    Maximum Bitrate
    Join Date
    Nov 2004
    Location
    Cali
    Posts
    640
    How exactly were you planning on putting them in parallel?
    I have found you an argument; I am not obliged to find you an understanding.
    Reply With Quote Reply With Quote
  3. 09-08-2005, 04:12 AM #3
    jvinis
    jvinis is offline
    Newbie
    Join Date
    Sep 2005
    Posts
    5
    This is my question to forum :
    How exactly can i putting LM2678 chips in parallel to get the desired amps and volts ?

    i have founded one solution (look at attachments).
    But i expect some help out there !!

    Thanks
    and sorry for my english
    Attached Images Attached Images  
    Reply With Quote Reply With Quote
  4. 09-08-2005, 06:17 AM #4
    lez
    lez is offline
    FLAC lez's Avatar
    Join Date
    Jan 2004
    Location
    UK
    Posts
    1,333
    Is the comp pin input or output, surely it cant be both.

    I would build 2 seperate circuits and join the outputs with a diode and 0.1ohm resistor, after all both coils wont produce the same output voltage for the same PWM due to differences in the windings.

    Lots of commercial designs do it that way, good or bad it works.
    Reply With Quote Reply With Quote
  5. 09-08-2005, 08:17 AM #5
    jvinis
    jvinis is offline
    Newbie
    Join Date
    Sep 2005
    Posts
    5
    Hi lez,

    I think that this schematic is 2 seperate circuits and the outputs are joined together to share the load current demand.
    I provide the above schematic with 1 LM2577 chip

    Lez can you send me one better design ?

    Can anyone tell me why mastero use 2 x MAX788 chips to produce 3.3v and not 2 x LM2678-3.3 chips in parallel and 2 x MAX787 chips to produce 5v and not 2 x LM2678-5 chips in parallel?

    Thanks
    Attached Images Attached Images  
    Reply With Quote Reply With Quote
  6. 09-08-2005, 10:07 AM #6
    cermy
    cermy is offline
    Newbie
    Join Date
    Sep 2005
    Posts
    1
    Its easy to get Samples from Maxim.
    Reply With Quote Reply With Quote
  7. 09-08-2005, 01:23 PM #7
    MatrixPC
    MatrixPC is offline
    MySQL Error MatrixPC's Avatar
    Join Date
    Sep 2003
    Location
    Beach City, Socal
    Posts
    4,053
    Take a look at mp3car[/AUTOLINK].com/vbulletin/showthread.php?t=25199&highlight=MK4.0 Sproggy/Mastero Mk4.0 thread [/url]. The thread has 4.0 and 4.1 design in there. 4.0 use National Semi LM2678 chips for 3.3V and 5.0V. The design doesn't work so well so the 4.1 come out to replace the LM2678 with the MAX chips.
    2004 Matrix XR A7N8X-VM/400 AMD XP-M 2500+, DS-ATX
    89 Supra Turbo P3 600E@750/Abit BE6 II, Alpine M-BUS Car2PC.
    Y2K Accord Dell GX150
    RoadRunner is the best FE PERIOD
    EmoRebellion is a SCAMMER
    Reply With Quote Reply With Quote
« Previous Thread | Next Thread »

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Forum Rules