Bootstrap Mosfet Driver

Discussion in 'The Projects Forum' started by afonso, Oct 5, 2013.

  1. afonso

    Thread Starter New Member

    Mar 29, 2009
    5
    0
    Hi,

    Assuming that I want switch on a circuit 3/4 times daily, using a mosfet associated with a driver ( for instance MOS FDP075N and FAN 7371 ), when I try to calculate the capacitor of bootstrap circuit based on Qtotal ( Fairchild AN-6076), what shall be the Ton used?
    As it's a very high value, the Qtotal became very high as well the Cboot!

    Any suggestions?
    thanks in advance
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,052
    3,244
    How long will you need the switch to be on? A bootstrap circuit is not practical for ON times longer than a few minutes, due to the discharge of the boot capacitor from the circuit leakage currents.
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,059
    A battery might be a better choice to replace the capacitor. It could last a very long time before needing replacement, but it would fail at some point.
     
  4. afonso

    Thread Starter New Member

    Mar 29, 2009
    5
    0
    Thanks for your help.
    Time on about 10 hours
    time off 14 hours

    If it's not the best way, shall we use an IGBT or other solution?
    A relay is not a good solution due the power lost to maintain the coil on/off


    The circuit has vinmax 120V and Imax 10A

    Any other ideia is welcome.
     
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,015
    1,531
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