output 35V from 24V

Discussion in 'The Projects Forum' started by Chaabane, Aug 25, 2010.

  1. Chaabane

    Thread Starter Member

    Nov 30, 2009
    37
    0
    Hello,
    i need to output 35 V output to control a mosfet (high Side).
    i have 4 battery (6V each) and i have LM2575-5 and LM2575-15 regulator already in the scheme, the max current won't matter,its less than 100mA

    is there any circuit that can boost 35V from 24V?
    will the LM2577-adj works ?

    thanks
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Why don't you simply use a high-side MOSFET gate driver IC? You'll get much better performance than if you tried to cobble something together out of discrete parts, and your PCB footprint will be smaller.

    For an example, look at the TC4431 (inverting) and TC4432 (noninverting) high-side gate drivers that Microchip makes. They're available in 8-pin DIP packages.
     
  3. Chaabane

    Thread Starter Member

    Nov 30, 2009
    37
    0
    Hi,
    i wish i can get mosfet drivers.... they're not available in algeria,so i had to make my custom driver
     
  4. tom66

    Senior Member

    May 9, 2009
    2,613
    214
    Is the output voltage critical?

    One thing you can try is a capacitive voltage doubler. You can build one around an oscillator and a capacitor, and a zener to clamp it at 35V. Since you're driving MOSFETs, the small capacitive charge pumps are probably not an option.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Do you have any more of these LM2575 IC's? If so, which do you have?

    Have you ever wound your own inductors or transformers before?

    Do you have an oscilloscope?

    Have a look at Ronald Dekkers' "Flyback Converters for Dummies" page. It's a good intro on making your own from items you can salvage.
    http://www.dos4ever.com/flyback/flyback.html
    Basically, you can use one of those LM2575 IC's with a transformer on the output instead of a simple inductor, along with some creative use of feedback resistors, to turn those buck IC's into a flyback converter.
     
    Last edited: Aug 25, 2010
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