Texas Instruments

UC3855AN

UC3855AN Description

The UC3855AN from Texas Instruments is an average current-mode Power Factor Correction (PFC) controller IC designed for high-efficiency AC/DC power supplies. Operating within a 15.5V to 20V supply range and supporting switching frequencies up to 500kHz, this IC ensures optimal power factor correction in demanding applications. Housed in a 20-pin DIP (Through Hole) package, it features a low startup current of 150 µA, making it energy-efficient during initialization. Although marked as obsolete, it remains a reliable choice for legacy designs requiring robust PFC performance.

UC3855AN Features

• Average Current Control: Ensures precise current shaping for near-unity power factor.
• Wide Operating Voltage (15.5V–20V): Compatible with standard auxiliary power rails.
• High Switching Frequency (500kHz): Enables compact magnetics and reduced passive component size.
• Low Startup Current (150 µA): Minimizes power consumption during boot-up.
• RoHS3 Compliant & REACH Unaffected: Meets environmental and regulatory standards.
• Through-Hole Mounting (20DIP): Simplifies prototyping and legacy system integration.

UC3855AN Applications

• AC/DC Power Supplies: Enhances power factor in server PSUs, industrial SMPS, and telecom rectifiers.
• LED Drivers: Improves efficiency in high-power LED lighting systems.
• Motor Drives: Optimizes input current waveform in variable-frequency drives.
• Renewable Energy Systems: Used in grid-tied inverters for compliance with harmonic standards.

Conclusion of UC3855AN

The UC3855AN excels in applications demanding high-efficiency PFC with its average current-mode control and 500kHz switching capability. While obsolete, its low startup current, wide voltage range, and through-hole packaging make it a pragmatic choice for legacy or cost-sensitive designs. Ideal for industrial power systems, LED drivers, and renewable energy infrastructure, it balances performance with regulatory compliance. Engineers seeking a proven PFC solution with straightforward integration may still find value in this IC.