What you need is "WLED Driver IC for Notebook Display".
Sample IC, pt4112 for 5-25V system;-
Notebook LCD display backlight
General middle-sized LCD backlight
Number of LEDs: 60(6x10)
Support: independent Enable(on/off) as well as PWM.
Sample IC, PT4110 for 2.7-5.5V system.
Number of LEDs: 32(4x8, 20 mA)
Support: Enable(on/off) and PWM.
P.S. Enable and PWM are logic level, it is friendly with Arduino. Some Information of above is combined with English doc and my translated form Chinese doc, so take it with salt.
PT4110's diagram is here;-http://arduino.cc/forum/index.php/topic,164487.msg1229672.html#msg1229672