H-Bridge Design

Discussion in 'The Projects Forum' started by Dukalev, Mar 10, 2009.

  1. Dukalev

    Thread Starter New Member

    Mar 10, 2009
    3
    0
    Hey I am also having trouble with the h bridge design I am trying to get a proof of concept to work and I can not get it to work in Pspice. I was wondering if anyone knows what I am doing wrong. I have been doing trouble shooting this for a long time and I seem to be burned out. All I want to do is use the p mosfets, and n mosfets with a LM393 inverter to drive the P mosfets. I am using V pulse just to simulate the different directions the load can take.
    [​IMG]
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    From the IRF540 Datasheet:

    VGS(th) Gate Threshold Voltage VDS = VGS ID = 250 μA 2 3 4 V

    4V difference is needed to barely turn on the MOSFET, you need to add MOSFET drivers (transistors, or a mosfet Driver IC) to get the gate voltage above 8V (Closer to Drain Voltage in this app, of 9.6V).
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    The power supplies are backwards on the LM393s.

    Also, you are going to need to get the gate voltage of the P-channel MOSFETs a lot higher than 5V to turn them off. Try 9.6V instead.
     
  4. Dukalev

    Thread Starter New Member

    Mar 10, 2009
    3
    0
    Alright so I got my H bridge circuit figured out, all it took was some time to clear my head. The problem is that right now I am trying to produce amplification separately with the LM393. For some reason when I spice it it does not seem to want to work. The circuit is below, is there just some dumb error I am making to not get me the desired voltage?
    [​IMG]
     
  5. Dukalev

    Thread Starter New Member

    Mar 10, 2009
    3
    0
    Oke so I looked it up and I added a "pull up" resistor to the circuit between the output and the 9.6V and now the circuit only follow the voltage without amplification.
     
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