Announcement

Collapse
No announcement yet.

Help with boost converter maths

Collapse
X
Collapse
 
  • Page of 1
  • Filter
  • Time
  • Show
Clear All
new posts
Previous template Next
    #1

    Help with boost converter maths

    Hi everyone I'm attempting to build a boost converter for a 16port hub it's psu only has 5volts and it needs a new fan but 12v is a load cheaper than 5v fans.

    I'm planing to use MC34063AP1G.

    What I need help with please is converting this into something I can understand


    For instance d = 3+(4-1)
    Attached Files
    My pc
    CPU : AMD PHENOM II x4 @ 3.5Ghz
    MB : ASUS M4A89TD PRO USB3
    RAM : Kingston ValueRAM 16gb DDR3
    PSU : Cooler Master 850W Silent Pro
    GPU : ATI Radeon HD 6850
    Tags: None
    #2
    Re: Help with boost converter maths

    You are making a fan controller?
    You know that's going to add heat too - right?
    .
    If you run a 12v fan on 5v it should run fine, just slower.
    So use a higher RPM [or thicker] 12v fan and the 5v power source....
    .
    Mann-Made Global Warming.
    - We should be more concerned about the Intellectual Climate.
    -
    Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
    - Dr Seuss
    -
    You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
    -

    Comment

      #3
      Re: Help with boost converter maths

      Also check if these guys will ship to you.

      http://www.allelectronics.com/make-a...ING-FAN/1.html
      Mann-Made Global Warming.
      - We should be more concerned about the Intellectual Climate.
      -
      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.
      - Dr Seuss
      -
      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
      -

      Comment

        #4
        Re: Help with boost converter maths

        Not fan controller
        1. I have developed a interest in boost buck conversion.
        2. The fan I have got wont start on 5v.

        Thanks for the site suggestion but they won't tell me the price to nz
        Also I'm not sure I think the fan is 15mm thick and it's tight.
        Last edited by joshnz; 02-03-2012, 06:15 AM.
        My pc
        CPU : AMD PHENOM II x4 @ 3.5Ghz
        MB : ASUS M4A89TD PRO USB3
        RAM : Kingston ValueRAM 16gb DDR3
        PSU : Cooler Master 850W Silent Pro
        GPU : ATI Radeon HD 6850

        Comment

          #5
          Re: Help with boost converter maths

          The psu of the 16 port hub may only provide a few amps of power on 5v.

          Technically, you should have 16 x 0.5A to fully power those ports, so that would be about 8A. However, I doubt the psu of the hub delivers more than 3A of power, and at such load, it would probably not do quite 5v, but rather about 4.6v-4.8v

          See for example this video, where a cheap chinese psu advertising 5v @ 1A can barely do 0.3A at about 4.6v :

          http://www.youtube.com/watch?v=T88ej...qDogWgYQcamJzV

          Next step is to keep in mind the efficiency of the step up converter which should be at about 70% ... so a 12v @ 0.15A fan would use about 2 watts of power, with the efficiency drop think of about 2.3 watts... at 5v that's already 0.5A of power.

          as for the calculations, you have to do them one after another from top to bottom...

          See https://cdn.badcaps-static.com/pdfs/...9237226842.pdf for a step down ...



          Vf is about 0.35v which is typical for a schottky diode , f is the frequency of the oscillator which you pick between 24khz and 44 khz let's say you pick 32 khz... assuming minimum 4.7v at input

          Vsat is in the datasheet...
          Figure 4 shows the saturation voltage....

          From there you just do the calculations making sure the measure units are the right ones.
          Last edited by mariushm; 02-03-2012, 07:35 AM.

          Comment

          Previous template Next
          Working...