ST Unveils L4983 PFC Controller for kW Power Supplies

STMicroelectronics has introduced the L4983, a highly integrated power-factor correction (PFC) controller designed for continuous conduction mode (CCM) architectures in switched-mode power supplies. The device integrates a proprietary multiplier emulator and distortion-optimization circuitry, allowing designers to implement PFC stages with fewer external passive components.

The controller targets power supplies ranging from several hundred watts to multiple kilowatts. Its totem-pole output provides a 3A source and 7A sink capability, enabling it to directly drive suitable power switches in high-power PFC stages. Typical applications include industrial and medical power supplies, servers, PCs, high-power lighting, and consumer electronics. The controller supports compliance with EN 61000-3-2 and comparable international requirements for input-current harmonics.

The L4983 incorporates three operating modes intended to reduce power consumption under light-load and standby conditions. Its burst mode can suspend switching activity at low or zero load and rapidly resume operation as the load increases, without requiring a complete soft-start sequence.

A pin-controlled idle mode offers another option to reduce consumption by stopping switching activity and disabling the internal error amplifier. The controller also features a disable mode that shuts down operation and subsequently resumes through a soft-start sequence. These functions can help power-supply designers meet efficiency requirements such as US Energy Star, the EU Ecodesign Directive, and the European Code of Conduct for power adapters.

The L4983 combines several protection mechanisms to improve system robustness. Overvoltage protection helps control output excursions during transient conditions, while an internal comparator provides cycle-by-cycle overcurrent protection. An inductor-saturation detection function limits abnormal current conditions and associated surges.

Additional control functions include line feedforward, which helps stabilize delivered power when the AC input varies, and startup verification of the voltage-feedback and current-sense signals to detect feedback-loop faults. Integrated soft-start further limits inrush current while maintaining output-voltage regulation.

ST also offers the EVL4983-350W evaluation board, which implements a 350W PFC pre-regulator with universal AC input and a regulated 400V DC output. The reference design achieves low total harmonic distortion across the load range and a peak efficiency of 97.4%, providing a practical platform for evaluating the L4983 in switched-mode power-supply designs.

Two production variants are available. The L4983A operates at a 65kHz switching frequency, while the L4983B operates at 130kHz. Both versions are currently in production and use a compact SO-8 surface-mount package.

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