IC engine electronic ignition circuit - has collector-emitter path of control transistor in base circuit of final stage transistor, with base regulation of control transistor

摘要

The IC engine ignition comprise a control circuit for the saturation state of the end transistor (20) in the primary circuit of the ignition coil (22). The saturation state is determined by measuring the collector voltage, or the difference of the collector and base voltages of the end stage transistor. the saturation state may be obtained in an inductive manner. The determination may also take place by measuring the ignition coil primary current across a current mirror circuit (20,21,27). In the base circuit of the end stage transistor there is incorporated the collector-emitter path of a control transistor (7), whose base excitation is carried out both via a control amplifier (15) of the control circuit and via a ignition control signal. The end stage transistor is controlled slightly above saturation. This keeps the lossy power as low as possible for protection of the end stage transistor.