STMicroelectronics has introduced a new phase shift control IC that can further boost the efficiency of resonant power conversion systems.

ST unveiled the STNRG599A and STNRG599B controllers, aimed at power supplies and lighting drivers, on the 26th. These products are characterized by being designed to maintain high efficiency even under no-load conditions.

The new product applies a phase shift control method optimized for resonant converter topologies, simultaneously improving output control stability and dynamic response characteristics.

In particular, by directly controlling the phase relationship between the half-bridge voltage and the resonant circuit current, sensitivity to component deviations is reduced and resistance to input voltage fluctuations is enhanced compared to conventional frequency control methods.

The STNRG599A is suitable for adapters, chargers, TVs, and industrial power supplies, and features a built-in X-capacitor discharge circuit to comply with safety standards.

On the other hand, the STNRG599B is designed for lighting drivers and supports stable, flicker-free operation even in deep dimming environments, and the discharge circuit has been excluded.

Both products support an operating frequency of up to 750kHz and a wide input voltage range, enabling them to handle applications ranging from 90W to several hundred watts.

Each IC drives external high-side and low-side switches through a complementary output structure with a 180-degree phase difference and is designed to maintain Zero Voltage Switching (ZVS) across the entire operating range.

This allows switching losses to be reduced and power conversion efficiency to be maximized.

Protection features have also been enhanced.

It comes standard with a protection circuit to prevent hard switching and a capacitive load protection function, and provides an overcurrent protection function that enables delayed shutdown and automatic restart through external pin settings.

It also includes a non-latch type DC brownout/brown-in protection function that cuts off operation if the input voltage exceeds the set range.

ST provides the EVLG599-250W to enable developers to quickly verify the effectiveness of phase shift control technologyLLC evaluation boards are also provided.

This board utilizes a SiP solution integrating the STNRG599A, synchronous rectifier, GaN FET, and half-bridge driver to achieve high-efficiency power conversion performance without a heatsink.

STNRG599A and STNRG599B are currently in mass production and are supplied in SO16N packages. Evaluation boards are available for purchase through ST's official distribution channels.