MOSFET switching

Discussion in 'General Electronics Chat' started by Rydaholic, Feb 4, 2014.

  1. Rydaholic

    Thread Starter New Member

    Feb 4, 2014
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    Hi,
    I want to make a buck converter, but the problem is that I can't specify whether I should use high side switch or low side to drive the mosfet using IRF2110. My application is buck. Please give some information about it. And Of course, I am a Newbie :(

    Thanks..!
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Generally speaking buck converters use high side PFET switches. Then depending on the input voltage you can just pull the gate to ground to turn it on. Might be a good idea to post the specs you want and the circuit you are thinking about.
     
  3. crutschow

    Expert

    Mar 14, 2008
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    3,229
    Most buck regulator ICs will specify the type of MOSFET needed. And there's no reason to design a buck regulator without using an IC dedicated to that purpose.
     
  4. Rydaholic

    Thread Starter New Member

    Feb 4, 2014
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    ronv,
    Thanks for reply.
    Is it necessary to use PFET Switches? If I use High-Side NFET switch? Isn't it suits my application better?
    My task is to take the energy from a 100Watt Solar panel and then distribute it to different modules of different ratings, in which i should have to buck or boost up the voltage level or may be invert it. First, I have to step down it, with high efficiency, so far as I could understand that, I need a Synchronous buck converter ( With Discrete ), in which two MOSFET's are used for switching, one is control switch( High side) and the other one is synchronous switch(low side). To completely on the mosfet's, I need a DRIVER IC (2110). Driver's input is command signal (microcontroller). Em also use a feedback signal to regulate the output voltage with variable loads. So if pwm command signal from micro controller is on the HIN pin(Driver's High side input), then what should be on LIN (Driver's low side input). Also tell me some thing about Floating Supply and Bootstrap operation. Again Thanks..! :)
     
  5. Rydaholic

    Thread Starter New Member

    Feb 4, 2014
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    crutschow,
    Thanks for reply,
    I can't use regulator IC, because all available regulator IC in market are of very low rating with maximum Iout of 5A, but I need some thing more than it, also that I have to make a system which have high stability, minimum power and heat dissipation, that's why I could'nt use these IC's. :(
     
  6. crutschow

    Expert

    Mar 14, 2008
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    An N-MOSFET can be used for a high-side switch on the plus side of the circuit but it needs a gate voltage about 10V above the source and drain voltage to be fully turned on. That can be provides by a bootstrap driver. It uses a capacitor in a bootstrap circuit to generate a voltage above the supply voltage. You can do that in discrete form but it's easier to buy a MOSFET driver specifically designed for that purpose.
     
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  7. Rydaholic

    Thread Starter New Member

    Feb 4, 2014
    15
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    No, em not going to drive the mosfet in discrete form, em using IRS 2110. Will it work and suits my application?
     
  8. Rydaholic

    Thread Starter New Member

    Feb 4, 2014
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    I think the input on the HIN (pin of High side input switch) is the pwm signal from microcontroller but my question is that what will be the input of LIN (pin of Low side input switch) of IRS 2110? might be the opposite pwm signal of HIN?
     
  9. crutschow

    Expert

    Mar 14, 2008
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    3,229
    Yes, the IRS2110 has a bootstrap to drive a high-side N-MOSFET switch and should work for you as long as you stay within its voltage limits.
     
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