T8 Tube

 Figure 1:8 inch LCD module backlight circuits.

MR16 

First calculate how much processing 2W load switching current . Assuming 80% efficiency , the input current is equal to Vout × Iout / Vin × efficiency = 10 × 0.18 / 5 × 0.8 = 450mA.CAT4139 inductive boost LED driver with 750mA ( min ) drive capability , it is very suitable for this application .

T8 Tube

Inductor current rating should be able to handle peak switch current without LED driver into saturation . Once saturation occurs , there will be current surges, because the function has become an inductive resistor , the circuit no longer work as expected . Suitable inductor current rating should be greater than or equal 80mA.

LED Flexi

LED during operation the maximum output voltage should be below the rated maximum output voltage. Since three LED series , in cold temperatures , the total could be as high forward voltage 11.4V (3 × 3.8V). 24V LED open circuit detection threshold is much higher than its limit. If the LED is off , the output voltage will rise and remain at 30V, time components in low power mode , the current from the power absorbed by only a few milliamps. 30V nominal output voltage capacitor is suitable.

Now consider a powered by a 12V 6W LED lights. You can use six high-brightness white LED connected in series to achieve with a 300mA constant current to drive a typical forward voltage of 3.3V.