Typical application circuit of NE5565

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Photocoupler

The NE5565 controller is a highly integrated solution designed for switching power supply applications, particularly in electronic ballasts. It incorporates two key control circuits: a PFC (Power Factor Correction) boost converter controller and a half-bridge oscillator circuit. The PFC section ensures a power factor above 0.99, significantly reduces AC current harmonic distortion, and provides protection against transient voltage spikes. Meanwhile, the half-bridge oscillator converts the DC output from the PFC into a high-frequency AC signal, which is essential for efficient lamp operation.

The NE5565 drives two external high-voltage MOSFETs, enabling precise regulation of lamp current, limiting peak lamp voltage, and offering comprehensive protection during power switching. This device operates within a wide temperature range of 0 to 85°C, making it suitable for a variety of industrial and commercial environments.

Key features of the NE5565 include:

• Integrated PFC and dimming control on a single chip, simplifying system design;
• Very low AC current harmonic distortion for improved energy efficiency;
• Supports variable frequency operation for better adaptability;
• Programmable preheating and ignition sequence with a three-step soft start;
• Lamp overvoltage protection to prevent damage under abnormal conditions;
• Eliminates voltage overshoot when the load is disconnected, enhancing system stability.

The typical application circuit of the NE5565 is illustrated above. T1 represents the high-frequency transformer used in the half-bridge oscillator, while T2 functions as the lamp current detection transformer. These components work together to ensure reliable and efficient operation of the electronic ballast system.