Advantages of AL5815/16 constant current controller.

Thread Starter


Joined May 31, 2017
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?


Joined Feb 8, 2018
If you just use a LED in series with a resistor and pulse width modulate, the brightness will vary with the supply voltage. It will also vary with temperature, particularly when driving a long string of LEDs. This circuit will control the LED current accurately, even with supply rail and temperature variation. It may be of very minimal benefit if the supply is well regulated and minor brightness variation due to temperature is acceptable. This circuit is very well suited for driving a single LED from a single lithium ion cell.