SPARK IGNITION TRANSFORMER WITH A NON-LINEAR SECONDARY CURRENT CHARACTERISTIC

An ignition transformer (10) for use with a spark ignition system (12) for an internal combustion engine (18) includes a central core (20), a primary coil (22), a secondary coil (24), and a magnetic return (28). The central core (20) defines a first end (20A) and a second end (20B). The primary coil (22) is used to vary magnetic energy into the central core (20) in response to a primary current (52) applied to the primary coil (22). The secondary coil (24) is used to generate a secondary voltage (56) in response to changes in the magnetic energy in the central core (20). The magnetic return (28) defines a return-path (58) to couple magnetic energy from the first end (20A) to the second end (20B). A permeability value of the return-path (58) is selected so the transformer (10) has a secondary-current versus time-response characteristic (400) that decays to fifty-percent (50%) of an initial secondary current (410) when ten percent (10%) to twenty-five percent (25%) of a burn-time interval (420) has passed.