LED driver simplifies low power lighting designs

The SOT26 packaged device integrates a 100V rated N channel mosfet with a pre biased NPN transistor and can drive chains of up to 30 series connected leds with currents from 20 to 350mA. The AL5801's open drain output operates between 1.1 and 100V, supporting common 12, 24 and 48V power rails, while the led current is set using an external low value resistor. By generating a 0.56V reference voltage across the resistor, the driver's internal control transistor helps minimise power losses and ensures sufficient supply voltage margin. Due to the reference voltage's negative temperature coefficient, the output current is automatically reduced at higher temperatures, helping to protect the led chain from any damage and improving overall circuit reliability. The AL5801's wide operating temperature range of -40 to 150°C means it can be mounted immediately adjacent to leds where pcb space is limited.