The STLD20D is an SOT-23 package that drives white LEDs with 80% conversion efficiency over a wide range of battery voltages. Up to four LEDs can be driven in series from a 2.5-V dc battery. Dynamic supply voltage rejection prevents backlight flickering. An LED disconnect switch reduces standby current (1 mA) leakage. Also, it includes soft-start functions and a shut-down mode with dimming control. Overvoltage and overtemperature protection are incorporated. A pulse-width-modulation input allows white LED dimming without reducing bias voltage, minimizing white-output color changes. A 3- by 3-mm QFN package is available as well. Price is $0.45 each in 100,000-unit quantities.