The MP4021A is a primary-sidecontrol offline LED lighting controller that achieves high power factor and accurate LED current for isolated single-power-stage lighting applications in a single SOIC8 package. The proprietary real-current control method accurately controls LED current from primary-side information. Eliminating the secondary-side feedback components and the optocoupler significantly simplifies the LED lighting system design. The MP4021A integrates power factor correction and works in boundary conduction mode to reduce the MOSFET switching losses. The extremely low start-up current and quiescent current reduces the total power consumption and provides a high-efficiency solution for lighting applications. The multi-protection features of MP4021A greatly enhance system reliability and safety. The MP4021A features over-voltage protection, short-circuit protection, cycle-by-cycle current limiting, VCC UVLO, and auto-restart over-temperature protection.