AnalogicTech痴 new WLED drivers reduce footprint of mid-range camera phones
(Technology News, 24 Jun 2008 )
Advanced Analogic Technologies has announced the AAT2848, a new trimode charge pump driver IC for white LED (WLED) backlight display and flash applications. By integrating four backlight channels capable of driving up to 30 mA each with two flash channels capable of driving up to 300 mA each, or 600 mA in parallel, in a small 3mm x 3mmTQFN33-20 package, this new device offers mid-range camera phone designers a highly attractive space-saving solution.
The AAT2848 is a dual-mode charge pump offering both 1X and 1.5X operation. The IC drives four backlight LED channels at up to 30 mA each using the charge pump in dual mode (1x and 1.5x) and two flash LED channels at up to 300 mA each in tri-mode (1x, 1.5x and 2x).
To enable, disable and set LED current, the AAT2848 features two of AnalogicTech痴 patented Simple Serial Control (S2Cwire) serial digital interfaces. For backlight functions the device can set current to any of 32 programmable levels. The flash LED outputs can be set independently across 16 programmable levels. Full scale current is independently set for backlight and flash using external resistors.
The new driver IC also features an innovative fade-in/fade-out function which gradually increases backlight LED brightness from off to fully on across a 63-step linear progression. Fade time is controllable by an external capacitor. By replacing microprocessor-based software schemes for the same function, this feature offers a smoother transition to full brightness while reducing software overhead.
The device also adds a user-programmable safety timer to protect the flash LEDs from thermal damage. This function can be used to terminate a flash event after a pre-determined period of time. Both the safety timer and flash/strobe operation is enabled via a separate flash enable pin.
