The FAN4855B is a highly integrated PWM controller designed for power factor correction (PFC) applications, manufactured by Fairchild Semiconductor, which is now part of ON Semiconductor. It is primarily used in AC-DC power supplies to improve power factor and reduce harmonic distortion.

Applications:

• AC-DC power supplies
• Adapters
• Electronic ballasts
• LCD TVs
• LED lighting
• Desktop PCs

Features:

• Power Factor Correction (PFC)
• Critical conduction mode (CRM) operation
• Low start-up current
• Over-voltage protection (OVP)
• Over-current protection (OCP)
• Open-loop protection (OLP)
• Under-voltage lockout (UVLO)

Benefits:

• Improves power factor, reducing energy waste and improving efficiency
• Reduces harmonic distortion, minimizing interference with other electronic devices
• Enhances power supply reliability through integrated protection features
• Simplifies power supply design with highly integrated functionality
• Reduces system cost with fewer external components

Additional Details:

The FAN4855B uses critical conduction mode (CRM) operation, which helps to minimize switching losses and improve overall efficiency. Its low start-up current allows for quick and efficient power-up. The integrated over-voltage protection (OVP), over-current protection (OCP), open-loop protection (OLP), and under-voltage lockout (UVLO) features provide comprehensive protection against various fault conditions, enhancing the reliability and safety of the power supply. By implementing power factor correction, the FAN4855B reduces the amount of reactive power drawn from the AC line, leading to lower energy consumption and improved power quality. The integrated functionality reduces the need for external components, simplifying the design process and lowering the overall cost of the power supply. It is designed to meet international standards for power quality and harmonic distortion, making it suitable for a wide range of applications.