SY5803 - Single stage Buck-Boost PFC controller


  • Valley turn-on of the MOSFET to achieve low switching losses
  • Aux-winding for ZCS detection and bias current optional
  • 0.3V current sense reference voltage leads to a lower sense resistance thus a lower conduction loss
  • Internal high current MOSFET driver: 1A  sourcing and 2A sinking
  • Low start up current: 15µA typical
  • Reliable short LED and Open LED protection
  • Power factor >0.90 with single-stage conversion
  • Compact package: SO8

Typical Application


The SY5803 is a single stage Buck-Boost PFC controller targeting at LED lighting applications. It drives the Buck-Boost converter in the quasi-resonant mode to achieve higher efficiency. It keeps the Buck-Boost converter in constant on time operation to achieve high power factor.


  • LED lighting
  • Down light
  • Tube lamp
  • PAR lamp
  • Bulb lamp