Step Up Converter 16-Pin WLP T/R

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 transitions to pulse-skipping mode at light loads. 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 other three regulators (LED3, LED4, LED5) are suitable for keyboard backlight functions or for driving signal indicators, and are programmable up to 5mA using a 32-step logarithmic dimming scheme. The low-current regulators (LED3, LED4, LED5) can be operated from the step-up converter or from a separate low-voltage source. The I²C interface controls all operational aspects of the current regulators, including: on/off state, LED current, ramp-up/ramp-down timers, and blink rate timers (LED3, LED4, LED5). The MAX8831 write/read addresses are factory programmed at 0x9A/0x9B (contact the factory for other address options). The MAX8831 features open/short LED fault detection, output overvoltage protection, thermal shutdown, and open-circuit Schottky diode detection, with the status of each fault monitored continually for readback through the I²C interface. The MAX8831 is available in a tiny 2mm x 2mm, 16-bump WLP package.

• Highly Integrated 28V Step-Up DC-DC Converter with Programmable Functionality Lowers System Cost
  • Integrated NMOS Power Switch
• Two 25mA Regulators for Display Backlighting
  • I²C-Programmable 50µA to 25.25mA Output Current
  • 128-Step Logarithmic Dimming
  • Individually Programmable Ramp (Up/Down) Timers
  • Low Dropout (200mV max)

Three 5mA Current Regulators for Keypad Lighting with I²C-Programmable 50µA to 5.0mA Output Current

• 32-Step Logarithmic Dimming
• Individually Programmable Ramp (Up/Down) Timers
• Individual Blink Rate and Duty Cycle Timers
• Low Dropout (150mV max)
• I²C Programmable Compatible with 1.8V Logic

Protection Features Increase Reliability

• Open/Short LED and Open-Circuit Diode Detection
• Thermal-Shutdown and Output Overvoltage Protection

High Efficiency and Low Shutdown Current Extend Battery Life

• > 90% Efficiency
• Pulse Skipping for Improved Light-Load Efficiency
• Ultra-Low 0.1µA Shutdown Current

Small Solution Size Saves Board Space

• Tiny 2mm x 2mm, 16-Bump WLP Package
• 2MHz Switching Frequency Allows Use of Tiny External Components