Overview
L484 is an electronic ignition controller special integrated circuit developed and produced by SGS-THOMSON, which is suitable for high-energy electronic ignition systems triggered by magnetic induction ignition signals. It has a complete protection design (such as: overcurrent, overvoltage, zero-crossing and battery polarity reverse connection protection functions), and can be matched with a variety of magnetic induction ignition signal generators; its working power supply voltage range is wide, It can be applied to automotive electronic ignition systems in harsh environments.
L484 is available in DIP-16 and SO-16 packages
Application note, closing angle control
The closing angle control circuit accurately controls the conduction time of the power tube Q (that is, the energization time of the ignition coil) according to the speed, the power supply voltage and the parameters of the ignition coil. In order to reduce loss, the saturation time of the power tube Q is usually limited to about 10% of each cycle of the ignition signal; therefore, the closing angle control circuit adopts a “variable threshold” design. At low speeds, the turn-on threshold is generally 200mV, while At high speed, the threshold value becomes negative, which makes the closing angle can be advanced by about 5%.
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