Portable media devices have increasingly larger displays and longer video playback, and require more power. The LM3530 from National Semiconductor Corp. (Santa Clara, CA) employs ambient light-sensing algorithms and content-adjustable backlighting to optimize displays, saving 55 percent of power.
The LM3530 LED driver has a 12-bump micro SMD package measuring only 1.615 mm × 1.215 mm × 0.425 mm. Logarithm and linear LED brightness mapping provides flicker-free dimming, and a fixed-frequency, 500 kHz boost converter provides high efficiency over the LED current range.
The LM3530 current-mode boost converter can supply up to 29.5 mA of power to 11 white LEDs from a single-cell lithium-ion battery. A I2C compatible interface allows the designer to adjust for lighting effects like fading, external ambient conditions and lighting level, as well as brightness and image performance.