L4985BTR

Overview

The L4985BTR is a monolithic integrated circuit functioning as a continuous conduction mode (CCM) power factor correction (PFC) controller for boost converters. It utilizes a proprietary multiplier emulator and THD optimizer to ensure low total harmonic distortion across all operating conditions. The device features an 800 V high-voltage startup block with integrated X-capacitor discharge, eliminating the need for external discharge resistors. It operates at a quasi-fixed frequency of 130 kHz, indicated by the 'B' suffix, and includes comprehensive protection mechanisms such as overvoltage, undervoltage, and inductor saturation protection.

Feature Summary

• Proprietary multiplier emulator ensures minimal total harmonic distortion in CCM and DCM modes
• Integrated 800 V high-voltage startup with active input filter capacitor discharge
• Totem-pole output stage capable of driving large MOSFETs or IGBTs
• Brownout protection compliant with medical equipment regulations

Applications

• Boost PFC pre-regulators for switch-mode power supplies
• Power supplies ranging from hundreds of watts to several kilowatts
• Medical equipment requiring compliance with IEC 60601-1-2 standards
• Consumer electronics meeting EN61000-3-2 and JEIDA-MITI energy efficiency standards

Procurement Notes

Verify the specific package type and tape-and-reel configuration against the manufacturer's official datasheet before procurement. Confirm that the 'B' suffix corresponds to the required 130 kHz switching frequency variant. Ensure compatibility with the intended PCB layout and thermal management requirements for high-power applications.

Selection Notes

Select this component when designing CCM boost PFC circuits requiring low component count and high efficiency. The integrated high-voltage startup simplifies design by removing external discharge resistors. Choose this variant over the 65 kHz option if higher switching frequencies are desired for reduced passive component size.

Part Context

The L4985 belongs to STMicroelectronics' family of power factor correction controllers designed for high-performance AC-DC conversion. It addresses regulatory requirements for harmonic distortion while offering robust protection features suitable for automotive and industrial environments. The device integrates advanced control algorithms to maintain performance under varying line and load conditions.

Replacement Considerations

The L4986A is a functional alternative operating at 65 kHz. Verify pin compatibility and switching frequency requirements when substituting. Ensure that the target application can accommodate the different operating frequency and that any changes in control loop dynamics are validated.