Powering LED strip from Arduino
A better solution instead of a Darlington is to use an Nch FET with RdsOn*0.15A&lt;=0.15V  or RdsON&lt;=1 Ohm with logic level 5V or Vgs(th)&lt;1.5V.  100mOHm Ron FET's have many solutions with Vt&lt;1.5V

Dan's IRLZ44NPBF can certainly do the job.

MOSFET  55V 41A 22mOhm 32nC LogLvl .TO-220-3 

Generally, you look for a FET that is rated for 20x the current you need to get the low voltage drop at 4.5V Vgs.