MAX8831 Datasheet, PDF (1/27 Pages) Maxim Integrated Products – High-Efficiency, White LED Step-Up Converter with I2C Interface in 2mm x 2mm WLP

19-4370; Rev 0; 11/08
EVALUATION KIT
AVAILABLE
High-Efficiency, White LED Step-Up Converter
with I²C Interface in 2mm x 2mm WLP
General 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 pro-
vides 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 com-
pact 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 volt-
age), 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 loga-
rithmic dimming scheme. The other three regulators
(LED3, LED4, LED5) are suitable for keyboard backlight
functions or for driving signal indicators, and are pro-
grammable up to 5mA using a 32-step logarithmic dim-
ming 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 address-
es 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
Features
♦ 28V Step-Up DC-DC Converter
Integrated NMOS Power Switch
> 90% Efficiency
Fixed 2MHz Switching
Pulse Skipping for Improved Light-Load
Efficiency
Tiny External Components
♦ I²C Programmable (0x9A Write/0x9B Read),
Compatible with 1.8V Logic
♦ Two 25mA Regulators for Display Backlighting
I²C-Programmable Output Current (50µA to
25.25mA)
128-Step Logarithmic Dimming
Individually Programmable Ramp (Up/Down)
Timers
Low Dropout (200mV max)
♦ Three 5mA Current Regulators for Keypad
Lighting
I²C-Programmable Output Current (50µA to
5.0mA)
32-Step Logarithmic Dimming
Individually Programmable Ramp (Up/Down)
Timers
Individual Blink Rate and Duty Cycle Timers
Low Dropout (150mV max)
♦ Open/Short LED and Open-Circuit Diode
Detection
♦ Thermal-Shutdown and Output Overvoltage
Protection
♦ Ultra-Low 0.1mA Shutdown Current
♦ Tiny 2mm x 2mm, 16-Bump WLP Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX8831EWE+T -40°C to +85°C
16 WLP
2mm x 2mm
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.