MAX8831
High Efficiency White LED Step-Up Converter with I²C Interface in 2mm x 2mm WLP
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Easily Drives Five Banks of 9 LEDs with Over 90% Efficiency Using an I²C Interface in a 2mm x 2mm WLP
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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
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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.
Applications
- Cell Phones
- PDAs
- Smartphones
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MAX8831
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Software & Part Ecosystem
Evaluation Kits 1
MAX8831EVKIT
Evaluation Kit for the MAX8831
Features and Benefits
- 28V Step-Up DC-DC Converter
- I²C Interface Control
- Two 25.25mA LED Strings (LED1, LED2) for Display Backlighting
- I²C-Programmable Output Current (50µA to 25.25mA)
- 128-Step Logarithmic Dimming
- Individually Programmable Ramp (Up/Down) Timers
- Three 5mA LED Strings for Keypad Lighting
- I²C-Programmable Output Current (50µA to 5mA)
- 32-Step Logarithmic Dimming
- Individually Programmable Ramp (Up/Down) Timers
- Individual Blink Rate and Duty-Cycle Timers
- RGB LED Module
- Alternative Power Supply (VIN2) for LED3, LED4, and LED5 Strings
- Open/Short LED and Open-Circuit Diode Detection
- Thermal Shutdown and Output Overvoltage Protection
- Lead(Pb)-Free and RoHS Compliant
- Fully Assembled and Tested PCB
Product Detail
The MAX8831 evaluation kit (EV kit) is a fully assembled and tested PCB for evaluating the MAX8831 white LED step-up converter. The MAX8831 EV kit operates from an input supply range of 2.7V to 5.5V and is controlled by an I²C interface. The MAX8831 features a 60mA, 28V PWM DC-DC step-up converter with five low-dropout LED current regulators. Each of the five current regulators accommodates up to 9 series LEDs (depending on LED string forward voltage), and are independently programmed using an I²C interface. 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, and LED5).
The MAX8831 EV kit also includes Windows® 2000/XP- and Windows Vista®-compatible software that provides a simple graphical user interface (GUI) for exercising the features of the MAX8831. The MAX8831 EV kit features an I²C interface to control the LED current, ramp-up/ramp-down time, and blink on/off time. To control the MAX8831 EV kit from a PC, order the CMAXQUSB command module along with the MAX8831 EV kit.
Applications
- Cell Phones
- PDAs
- Smartphones