RESONANT IGNITOR CIRCUIT FOR LAMP WITH A VARIABLE OUTPUT CAPACITANCE BALLAST

摘要

A resonant igniter circuit (11) employs a switch ignition branch and a resonant ignition branch. The switch ignition branch includes a pair of ignition switches (M1, M2) connected in series with a switch node (Nl). The resonant ignition branch includes an ignition coil (L2) and an ignition transformer (T2). Ignition coil (L2) is connected in series with switch node (NI) and a primary winding of ignition transformer (T2). In operation, a serial inductance of ignition coil (L2) is at least fifty (50) times greater than a resonant inductance of ignition transformer (T2) and ignition transformer (T2) has an air-gapped core between a primary winding and a secondary winding to thereby facilitate an impedance of a power stage of the resonant ignition branch as seen from a source as always being inductive over an entire range of output capacitance.