Power Factor Correction (PFC) and PWM Controller Combo# Technical Documentation: FAN4803CP1 Power Factor Correction (PFC) Controller
Manufacturer : FAIRCHILD (now part of ON Semiconductor)
Component Type : Integrated PFC/PWM Combo Controller
Package : 20-Pin PDIP (Plastic Dual Inline Package)
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## 1. Application Scenarios (Approx. 45% of Content)
### Typical Use Cases
The FAN4803CP1 is a monolithic integrated circuit designed for high-performance, offline switch-mode power supplies (SMPS). Its primary function is to implement Power Factor Correction (PFC) and Pulse Width Modulation (PWM) control in a single chip, enabling the design of compact, efficient, and cost-effective AC-DC power supplies.
* Single-Stage PFC & PWM Control: It integrates the control loops for both the PFC boost pre-regulator and the downstream PWM converter (typically a flyback or forward converter) into one device. This eliminates the need for two separate controllers, reducing component count and board space.
* Critical Conduction Mode (CrM) PFC: The PFC section operates in Transition Mode (also known as Boundary Conduction Mode or CrM), where the boost inductor current is allowed to reach zero before the next switching cycle begins. This mode offers a good balance between efficiency, EMI performance, and component sizing.
* Current-Mode PWM: The PWM controller uses current-mode control for the downstream DC-DC stage, providing inherent cycle-by-cycle current limiting, simplified loop compensation, and good line transient response.
### Industry Applications
This controller is a cornerstone component in power supplies requiring compliance with international harmonic current standards (e.g., IEC 61000-3-2) and high efficiency targets.
* Desktop PC & Server Power Supplies (ATX/SFX): Used in Silver, Gold, and Platinum-rated PSUs to achieve high power factor (>0.99) and meet energy efficiency standards like 80 PLUS.
* Industrial Power Systems: Provides robust and reliable PFC for machinery, motor drives, and automation equipment, improving grid power quality and reducing infrastructure stress.
* Telecommunications Infrastructure: Employed in rectifiers and power shelves for telecom systems where high power density and reliability are paramount.
* High-Power Adapters & Chargers: For professional laptops, workstations, and industrial equipment where a high-power, single-cord AC input is required.
* LED Lighting Drivers: In high-power LED drivers (e.g., for street lights, stadium lighting) where PFC is mandated and high efficiency is critical.
### Practical Advantages and Limitations
Advantages:
* High Integration: Reduces BOM count, PCB area, and design complexity compared to two-chip solutions.
* Excellent Performance: Achieves high power factor (>0.99) and low total harmonic distortion (THD < 10%).
* Interleaved Operation: The PFC and PWM stages operate 180° out of phase. This significantly reduces the ripple current on the bulk capacitor, allowing for the use of smaller, longer-life capacitors. It also reduces conducted EMI.
* Built-in Protections: Includes undervoltage lockout (UVLO), overvoltage protection (OVP) for PFC output, and peak current limiting for both stages.
* Reduced Stress: The phased operation reduces peak current demands from the input rectifier and bulk capacitor.
Limitations:
* Fixed PFC Mode: Operates only in Critical Conduction Mode. While efficient, CrM limits the maximum practical power level (typically up to ~300W) due to increasing frequency and switching losses at high line/light load. For higher power, Continuous Conduction Mode (CCM) controllers are more suitable.
* Design Complexity: While integrated,
