The MAX8831 integrates a 60mA, 28V PWM DC-DC step-up converter with five low-dropout LED current regulators for display and keypad backlighting in cell phones, PDAs, and other portable devices. The IC provides up to 90% efficiency over the entire input voltage range of 2.7V to 5.5V. The step-up converter operates at a fixed 2MHz switching frequency, enabling the use of very small external components to achieve a compact circuit area. For improved efficiency, the step-up converter automatically operates in pulse-skipping mode at light loads.
Each current regulator accommodates up to 9 series LEDs (depending on LED string forward voltage), and is independently programmed using an I2C interface. Two of the current regulators (LED1, LED2) are intended to support display backlight functions and are programmable up to 25.25mA using a 128-step logarithmic dimming scheme.

Applications

Cell Phones
PDAs
Smartphones

The MAX8831 detects an open external Schottky diode by sensing VOUT before turning on the step-up converter. If VOUT is above 0.8V (typ), the MAX8831 allows the step-up converter to turn on. If VOUT is less than 0.8V (typ), indicating that the external Schottky diode is open, the MAX8831 is put into standby state, the ON/OFF control register bits for the LEDs are set low, and the step-up converter stops switching. Bit 2 (OSDD) of the STAT2 register is updated to a 1 to indicate that an open Schottky diode event has occurred.

Read more: http://datasheets.maxim-ic.com/en/ds/MAX8831.pdf