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High Efficiency White LED Step-Up Converter with I²C Interface in 2mm x 2mm WLP

Easily Drives Five Banks of 9 LEDs with Over 90% Efficiency Using an I²C Interface in a 2mm x 2mm WLP

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • 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

Applications/Uses

  • Cell Phones
  • PDAs
  • Smartphones

Description

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.

Simplified Block Diagram

MAX8831: Typical Operating Circuit MAX8831: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.