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MOSFET for electronic ignition?

Discussion in 'Electronic Design' started by Paul Burridge, Nov 25, 2004.

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  1. Hi all,

    Would a power Mosfet be an appropriate choice for driving the primary
    side of a EHT ignition coil? If so, any recommendations as to type
    number would be appreciated. If not, what other device would be better



  2. The IRGB14C40L IGBT is designed for electronic ignition circuits. This is a
    very strange IGBT since it uses logic level gate drive. It also expects a
    1k resistor in series with the gate. The collector-emitter breakdown
    voltage is self clamped to about 400V, so ignition circuits built with this
    device can be very simple.
  3. IGBT's here's a few:,4460,,00.html?id=604

    logic level so I'd think you can drive them directly with an mcu,
    build-in ~400V clamp so you won't kill the coil in case the spark
    plug wire is removed etc.

  4. kell

    kell Guest

    Get the real thing: an IGBT made SPECIFICALLY for driving
    an ignition coil. For example:
    My hobby is building electronic ignitions for antique vehicles.
    I used the fairchild IGBT in a couple of circuits.
    I've used a couple other devices from other manufacturers.
    If I have the time I'll look for the part numbers.
    In the meantime just search for
    "ignition coil igbt" or some such.

    I tried mosfets and igbt's that don't have clamping, and they
    sometimes work and sometimes don't. The automotive igbt's
    are your best bet.
  5. kell

    kell Guest

    By the way, what is EHT? My applications have all been simple
    transistor-switched inductive ignitions. If you are using capacitive
    discharge the clamping aspect might not be as important, and an
    ordinary power mosfet (no clamping), with the proper voltage rating,
    might work.

    Old fashioned ignitions that have a set number of degrees of dwell (as
    opposed to modern ignitions, which have dwell control and
    low-resistance coils) will heat up a garden-variety mosfet, like the
    IRF 740. If the kickback doesn't kill it. You would have to find a
    high voltage mosfet with a low Rds and also be stuck with having to
    make a clamping circuit using discrete components to protect the
  6. Okay, thanks all! Will look into them.
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