Models in a series of six white-LED drivers are optimized to run off of battery sources like lithium-ion (Li-ion) cells. They include two switched-capacitor constant-current drivers (LM2794/2795), two switched-capacitor constant-voltage drivers (LM3354/3355), and two magnetic boost converters (LM2703/2704).
Able to power display backlights, the LM2794 and -2795 generate four current sources matched to ±0.5% for a total of 80 mA. The buck-boost LM3354 and -3355 can drive multiple LEDs in a keypad backlight, where they produce a regulated 1.8, 3.3, or 4.1 V (or custom value). Average efficiency is 80%.
The LM2703 and -2704, requiring an external inductor, drive up to four white LEDs in series and several strings of series LEDs at once. The LM2704 also can deliver 20 mA at 20 V with 85% efficiency. In 1000-piece quantities, unit pricing for the series starts at $0.85.
National Semiconductor Corp., www.national.com/see/wled; (800) 272-9959.