L4981B

Overview

The L4981B is a Power Factor Correction (PFC) pre-regulator controller designed for high-efficiency power supplies with sinusoidal line current consumption. It operates in Line Modulated Frequency Average Current Mode, optimizing input filter size while maintaining low noise sensitivity without slope compensation. The device supports universal mains inputs from 85V to 265V and integrates essential functions including a power MOSFET gate driver, error amplifier, under voltage lockout, current sense, and soft start. It features integrated overvoltage and overcurrent protection to minimize external component count.

Feature Summary

• Line Modulated Frequency Average Current Mode operation for optimized input filtering
• Integrated protections including overvoltage and overcurrent limits
• Universal input capability supporting 85V to 265V mains voltages
• High current bipolar and DMOS totem pole output for gate driving

Applications

• High efficiency-mode power supply designs
• Systems requiring sinusoidal line current consumption
• Universal input AC-DC pre-regulators

Procurement Notes

Verify the specific suffix against official STMicroelectronics documentation to confirm package type and tape/reel specifications. Ensure compatibility with required thermal and electrical ratings for the target application environment before finalizing procurement decisions.

Selection Notes

Select the L4981B when line-modulated frequency operation is preferred to reduce input filter size compared to fixed-frequency alternatives. This model requires an external divider for precise overcurrent programming, distinguishing it from resistor-programmed variants. Validate that the average current mode PWM architecture aligns with system noise and distortion requirements.

Part Context

The L4981B belongs to the L4981 family of PFC controllers realized in BCD 60II technology. While the L4981A offers fixed frequency operation, the L4981B provides line modulated frequency functionality. Both variants share core control features but differ in switching strategy and overcurrent programming methods.

Replacement Considerations

The L4981A is a functional alternative within the same family, offering fixed frequency operation instead of line modulation. Verify that the change in switching frequency strategy and overcurrent programming method (resistor vs. external divider) meets the design requirements.