MAX8831

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 MAX8831 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 transitions to pulse-skipping mode at light loads.

Features of the MAX8831 are:(1)integrated NMOS power switch; (2)> 90% efficiency; (3)fixed 2MHz switching; (4)pulse skipping for improved light-load efficiency; (5)tiny external components; (6)128-step logarithmic dimming; (7)individually programmable ramp (up/down) timers; (8)low dropout (200mV max); (9)open/short LED and open-circuit diode detection; (10)thermal-shutdown and output overvoltage protection; (11)ultra-low 0.1A shutdown current; (12)tiny 2mm x 2mm, 16-bump WLP package.Each of the five current regulators 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 25mA using a 128-step logarithmic dimming scheme.

The absolute maximum ratings of the MAX8831 can be summarized as:(1)IN to GND:-0.3V to +6.0V;(2)storage temperature range:-65 to +150;(3)VDD, COMP to GND:-0.3V to (VIN + 0.3V);(4)junction temperature:+150;(5)OUT, LX, LED1LED5 to GND:-0.3V to +30V;(6)continuous power dissipation:660mW.Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied.Exposure to absolute maximum rating conditions for extended periods may affect device reliability.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 MAX8831 operates at a fixed 2MHz switching frequency, enabling the use of very small external components to achieve a compact circuit area.