EFS3A, EFS31 fluorescent lamp special integrated circuit

The fluorescent lamp starting circuit made with EFS3A and EFS31 integrated circuits is shown in Figure 2-133. The electronic starting part is inside the dotted box , and the ordinary fluorescent lamp
circuit is outside the box .     After closing the power switch S, AC voltage is applied to pin 3 of A2, and pin 2 can output a DC voltage of about 12V, which is applied to pin 12 of A1. During the starting process , when the voltage on Cl is charged above the starting threshold voltage of AI, Al is started, the internal electronic switches on its pins 13 and 14 are turned on, and the current passes through the filament for preheating. When the preheating time reaches 1.5s , the current reaches the shutdown level (Iso-350mA), and Al will drive the switch in A2 to turn off. At the moment when the switch is turned off, a high-voltage pulse with an amplitude of more than 1000V will be generated at both ends of the ballast L and applied to both ends of the lamp to quickly start the lamp. The ignition voltage when the switch is turned off will be clamped by A2 at 1350V to prevent higher peak voltage from breakdown of the lamp. If it is not started when lighting, Al and A2 restart the preheating start process . A counter in A1 limits the number of restarts to 7 . If none of the eight starts is successful, the integrated circuit enters standby mode and stops starting. If the lamp is aged and cannot be started successfully using a traditional starter, it can often still be successfully lit using this electronic starter. If the lamp expires or is damaged, the starter will automatically shut down.     The capacitor C connected in parallel across the lamp is used for power factor correction.     The traditional starter cannot start the ignited lamp in a low temperature environment, but this circuit can ignite it smoothly.