The MP3309 is a WLED step-up converter for 2.7V-to-5.5V input that uses peak-current mode to regulate the LED current sensed through an external, low-side resistor. The 200mV feedback voltage and synchronous rectification reduces power loss and reduces PCB space requirements. For non-synchronous mode, setting an internal register can disable the rectifier MOSFET to save driver losses. The MP3309 features a programmable switching frequency to optimize efficiency. It supports both analog and PWM dimming. In addition, the MP3309 has LED open protection, cycle-by-cycle current limit protection, Under voltage protection and thermal shutdown protection -. The I2C interface can set the protection indication bits and over-voltage protection point.