Advanced PFC controller integrates multiple features for high-end AC-DC adapters

Power Electronics / Power Management

18 April 2007 Power Electronics / Power Management

STMicroelectronics has introduced an advanced PFC (power factor corrector) controller designed to be used in PFC pre-regulators in high-end AC-DC adapters and chargers for laptop PCs and game consoles, in desktop PCs and servers, and in switched-mode power supplies (SMPS) handling up to and over 250 W.

The L6563 - based on the core of the company's successful L6562 controller - integrates a broad range of additional functions to increase safety and efficiency while minimising the need for external components.

This current-mode PFC controller operates in transition mode (TM) which the company says provides a highly cost-effective solution for applications in the region of 100 W to 300 W; power in excess of 400 W can be managed by implementing ST's patented fixed-off-time (FOT) architecture, which increases power capability while maintaining the simplicity and affordability of transition mode operation.

ST has added new safety features: brownout and feedback disconnection protection. The former is a non-latched device shutdown function that can be activated when mains undervoltage is detected. The latter prevents uncontrolled output voltage rise, in case of failure of the voltage regulation control loop.

In addition, the IC provides input voltage feed-forward, tracking-boost operation, inductor saturation detection and leading-edge blanking, as well as a direct interface to the cascaded DC-DC converter's PWM controller. Voltage feed-forward can be used to compensate for gain variation with the input voltage, improving the stability of the loop and the transient response to sudden mains voltage changes. Optionally, the chip can be programmed to work with the tracking-boost approach, where the output voltage follows variations in the mains supply voltage. Inductor saturation detection protects against a potentially fatal condition in which its current can reach an abnormally high level.

The PWM controller interface is used to stop the operation of the converter in case of anomalous conditions in the PFC stage, and to turn off the PFC when the converter's load falls below a given threshold, enabling compliance with common energy saving recommendations.

The L6563 is suited for use with ST's L6668 PWM and L6599 Resonant Controllers and comes in an SO14 package.

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Power Electronics / Power Management

Advanced PFC controller integrates multiple features for high-end AC-DC adapters

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