| 摘要 |
An off-time control circuit drives an output transistor connected in series with a primary winding of an ignition coil while controlling the off-time in each ignition period so that the ratio Ti/T between the period of time Ti, during which the level of primary current supplied to the primary winding of the ignition coil attains a predetermined setting, and the ignition period can be maintained constant. The output from a current detecting resistor connected to the primary winding is applied to a rising time detecting circuit which detects the rising time of the primary current from the current supply starting time to the time of attainment of the predetermined setting. The off-time control circuit controls the starting time of power supplied to the output transistor depending on the output from the rising time detecting circuit. |
