The series connection allows the LED current to be identical for uniform brightness. Its low on-resistance of NFET and feedback voltage reduce power loss and achieves high efficiency. Fast 1MHz current-mode PWM operation is available for input and output capacitors and a small inductor while minimizing ripple on the input supply. The OVP pin monitors the output voltage and stop switching if exceeds the over-voltage threshold. An internal soft-start circuit eliminates the inrush current during start-up.