STMicroelectronics’ flyback controller boosts LED performance

STMicroelectronics’ HVLED101 90-400V flyback controller for LED-lighting applications up to 180W enhances performance and simplifies design through extensive feature integration, patented control techniques, and support for primary-sensing regulation.

Joining ST’s HVLED family of high-power-factor controllers, the HVLED101 contains 800V startup circuitry that cuts the LED turn-on time to less than 250ms. High-voltage input-sensing circuitry and a maximum power-control (MPC) engine are also integrated to ensure consistent power output as the line voltage fluctuates.

This lets designers choose smaller and lower-cost external passive components to handle worst-case line conditions. Primary-sensing regulation without isolated feedback further reduces the bill of materials and enhances reliability.

Among the patented innovations, ST’s input-current shaping algorithm lowers total harmonic distortion (THD) and maximizes the power factor. Also, the HVLED101 is the first high-power factor flyback controller to implement ST’s new valley-locking technique to minimize audible noise, improve regulation, and reduce distortion. At steady state in quasi-resonant operation, valley locking fixes the number of valleys skipped until a significant change in output power or input voltage is detected.

Together, current shaping and valley locking enhance the power factor and THD even at low and medium loads. Flyback converters controlled with the HVLED101 can achieve 5% THD at full load and 10% at 1/3 load to meet leading ecodesign codes.

In addition, designers can program the delay time after zero-crossing detection in pure quasi-resonant operation using an external resistor. By ensuring gate turn-on at the lowest point of the valley, the HVLED101 minimizes energy losses and electromagnetic emissions (EMI). Overall, the HVLED101 enables converters to achieve maximum efficiency above 90% and no-load power below 100mW.

All necessary protection is built-in, including overcurrent protection, input over-voltage protection, and brownout protection. There is also a smart auto-reload timer (ART) that allows latch-free operation of all protection mechanisms to ensure high reliability and a superior consumer experience.