The MP4001 is a high efficiency step-down converter designed for driving the high brightness Light Emitting Diodes （LEDs）。 The MP4001 drives external MOSFET with boundary conduction mode which features no reverse recovery loss in the freewheeling diode， soft turn on with zero-current and valley voltage for the power MOSFET. Such operation mode can achieve very high efficiency and in the same time minimize the inductor value and size. With the boundary conduction control mode， the LED current can be well regulated by control the MOSFET peak current which is sensed through an external resistor. Its low 300mV feedback voltage reduces power loss and improves the efficiency. The MP4001 integrates a high-voltage smart LDO， which allows the AC input to power up the IC directly. The smart LDO sinks current when the input voltage is lower than 24V to achieve higher efficiency. The MP4001 implements both PWM and DC input burst dimming The MP4001 features output short protections， maximum switching frequency limitation， under-voltage lockout and thermal shut down.