Santa Clara, Calif.—National Semiconductor's LP3958 and LP5526 lighting management units (LMUs), for cell phones and other handheld devices, control up to 20 series-connected LEDs in display backlights, and keypad, RGB and camera flash LEDs.
The LMUs drive from two to five strings of four series-connected LEDs, depending on the application. The devices, which come complete with I2C interface, are optimized for use in single- or dual-display phones, as well as large display PDA phones. Each features three general-purpose input/outputs (GPIOs) to trigger lighting functions such as Flash or to control additional device-enable signals.
The LP3958 delivers up to 70 mA for powering display backlight LEDs; the LP5526 delivers up to 150 mA for powering display backlight and Flash LEDs. In single and dual displays, the LP3958 LMU drives up to eight white LEDs grouped as four series-connected LEDs per string, with typically one string per display. Display backlight fade-in and fade-out are controlled via a two-wire, low-voltage, I2C-compatible interface. For keypads, three series-connected LED strings of up to four LEDs each can be independently controlled for gaming and navigation applications.
The LP5526 has the same features and packaging as the LP3958 and can drive multi-die serial-flash LEDs in camera Flash (up to 3 watts) and torch applications. Also, in the case of a software problem, the LP5526 features an internal safety timer to protect Flash LEDs from aging. With the LP5526, the Flash LED output can also be used to drive single or series-connected RGB LEDs.
Click here for additional information on the LP3958,
and here for the LP55526. The LP3958 and LP5526 are available now in a 2.5-by-2.5 mm, 25-bump micro SMD packages. The LP3958 is priced at $1.60 each, and the LP5526 is $2 each, both in 1k-unit quantities.
National Semiconductor, 1-800-272-9959, www.national.com