LP8549B1SP U7750

This is the LED driver for certain Retina Macbook Pros. It controls the DC to DC boost circuit that turns 12v into 26-39v for your laptop's screen light. If you want the surrounding resistors & diodes for different board types, look below!

Do be careful that SMC_LID is 3.42v before you even think of replacing this chip. Remember, if the laptop thinks it's closed, the screen won't light up!

This chip rarely dies so do check everything else before replacing it.  Check the LCD connector and cable. Check that you are using the proper screen from the proper year - on A1398/15" models, 2015/2016 LCDs will not work properly in older Retinas, and 2012-2014 LCDs will not work properly in newer retinas. On 13" models htis is even further annoying. 2012 LCDs will not work properly on 2013/2014/ models, 2013/2014 LCDs will not work properly on 2015/2016 models. 

Please check to ensure that this is the proper chip for your logic board.