As an example, the circuit using the LM3405A shown on his slide is designed to drive one InGaN WLED cycling at four different current levels: 0, 125 mA, 250 mA, and 700 mA with a peak-to-peak ripple current of 40 mA or less. The input is 4.2 V to 4.5 V from three AA batteries; the Vo is approximately 3.7 V at 700 mA current; and the switching frequency is 1.6 MHz (typical). For a complete look at this reference design visit the LED reference design library on ti.com.