New LCD board for A10 LIME

[electrolab]

Hello everyone
I am on a project for designing an LCD touchscreen board for the A10 Lime. I am using a different 5" screen from formike. The part which i can't understand is the backlight driving in both A13-LCD7" and A13-LCD4.3". Obviously A13-LCD7" has a build in DC-DC convertor for backlighting which is not stated in the lcd datasheet. Meanwhile in the A13-LCD4.3" this is well stated in the datasheet as backlighting needs 28V. Now, it is obvious the difference between backlight control of these two are big.
In the LCD i want to use, it is mentionned that the backlight leds are 12 leds with 6 parallel to the other 6 which needs a 19.2 volts and 40mA.
The AP3031 driver is stated as a good one for 7" to 10" http://www.mouser.com/ds/2/115/AP3031-271462.pdf and i don't see why it is not used for A13-LCD4.3"
Thanks for the help!
Regards