Introduction
The LC5500 series is the power IC for the isolated type LED driver which has an incorporated power MOSFET, designed for input capacitorless applications, and making it possible for systems to comply with the harmonics standard (IEC61000-3-2 class C). The controller adapts the average current control method for realizing high power factors, and the quasi-resonant topology contributes to high efficiency and low EMI noise. The series is housed in either DIP8 or TO-220F-7L packages, depending on output power capability. The rich set of protection features helps to realize low component counts, and high performance-to-cost power supply.

FEATUREs and Benefits
• DIP8 package (LC551xD/LC552xD) and TO-220F-7L package (LC552xF)
• Integrated on-width control circuit (it realizes high power factor by average current control)
• Integrated startup circuit (no external startup circuit necessary)
• Integrated soft-start circuit (reduces power stress during start-up on the incorporated power MOSFET and output rectifier)
• Integrated bias assist circuit (improves the startup performance, suppresses VCC voltage droop during operation, allows reduction of VCC capacitor value as well as use of a ceramic capacitor)
• Integrated Leading Edge Blanking (LEB) circuit
• Integrated maximum on-width limit circuit
• Dual-chip structure, with an avalanche-guaranteed power MOSFET (allows simplified surge suppressing circuits)
• Protection features:
   ▫ Overcurrent protection (OCP): pulse-by-pulse
   ▫ Overvoltage protection (OVP): auto restart, OVP activating pins vary by product series:
   ▫ Overload protection (OLP): auto restart
   ▫ Thermal shutdown (TSD): halts switching operation and latches in the off-state