I just read the article on the AL5815/16 chips, and I'm not sure how they would be useful. In order to control the output current, the chip must receive a PWM signal, the only difference between the 2 flavors being the range of frequencies they accept. But one can control a bipolar power transistor or MOSFET directly with a PWM train on the base/gate without the need of a current sense resistor in the high-current path. Why would one select one of these chips to control a LED, say?