The AAT2842 is a highly integrated charge pump with dual linear regulators optimized for systems operating with lithium-ion/polymer batteries. The charge pump provides power for both white LED backlight/keypad and flash. Up to four backlight LEDs can be driven at up to
30mA each and keypad LEDs can be driven using lower currents set by the S2Cwire interface. In addition, up to four flash LEDs can be driven with up to 600mA total. Two separate S2Cwire? (Simple Serial Control?) serial digital interfaces are used to enable, disable, and set the current to one of 16 levels for both backlight and flash LEDs. Backlight/keypad and flash current settings are also controlled through external resistors for increased versatility with reduced accuracy and matching. Backlight/ keypad current matching is 1% for uniform display
brightness, and flash current matching is 4% for uniform power dissipation. An internal flash timer set by an external capacitor protects the flash LED should a fault occur.