L4986B

Overview

The L4986B is a continuous conduction mode (CCM) power factor correction controller designed for boost converter pre-regulators. It utilizes a proprietary multiplier emulator and THD optimizers to ensure low Total Harmonic Distortion across all operating conditions. The device operates in quasi-fixed frequency mode at 130 kHz, distinguishing it from the 65 kHz variant. Key integrated features include an 800 V high-voltage startup block with X-capacitor discharge circuitry, enabling compliance with safety regulations without external discharge resistors. It supports EN61000-3-2 and JEIDA-MITI standards for power ranges spanning hundreds of watts to several kilowatts.

Feature Summary

• Proprietary off-time modulator ensures quasi-fixed frequency operation for consistent performance
• Integrated 800 V high voltage startup block includes X-capacitor discharge for safety regulation compliance
• Advanced protection mechanisms including overvoltage, brownout, feedback loop failure, and boost inductor saturation detection

Applications

• CCM-operated boost PFC pre-regulators compliant with EN61000-3-2
• Power supplies requiring JEIDA-MITI compliance
• Medical equipment designs adhering to IEC 60601-1-2 brownout requirements
• Systems targeting Energy Star and DoE energy saving guidelines

Procurement Notes

Verify the specific suffix 'B' confirms the 130 kHz switching frequency option, as the 'A' variant operates at 65 kHz. Confirm package availability matches the SOIC pin configuration. Ensure design documentation references the correct high-voltage startup characteristics and X-capacitor discharge capabilities for safety compliance verification.

Selection Notes

Select this component when CCM operation is required for higher power applications compared to transition mode controllers. The 130 kHz frequency offers a trade-off between component size and switching losses. Consider the integrated protections and startup features if minimizing external component count and meeting strict safety standards are primary design constraints.

Part Context

The L4986 belongs to STMicroelectronics' portfolio of power factor correction controllers, which also includes transition mode devices like the L6562A and L6563S. Unlike TM controllers, the L4986 series targets continuous conduction mode for higher power densities. It complements other PFC solutions by offering fixed off-time modulation techniques that bridge the gap between TM affordability and CCM current capability.

Replacement Considerations

The L4986A serves as the direct functional alternative within the same family, differing only in the switching frequency specification (65 kHz vs 130 kHz). Designers must verify that the control loop compensation and magnetic components are suitable for the selected frequency variant.