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MAX8831EWE+T

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28
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 I
2
C
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 I
2
C 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 I
2
C interface.
The MAX8831 is available in a tiny 2mm x 2mm, 16-bump
WLP package.
Applications
Cell Phones
PDAs
Smartphones
Features
o 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
o I
2
C Programmable (0x9A Write/0x9B Read),
Compatible with 1.8V Logic
o Two 25mA Regulators for Display Backlighting
I
2
C-Programmable Output Current (50µA to
25.25mA)
128-Step Logarithmic Dimming
Individually Programmable Ramp (Up/Down)
Timers
Low Dropout (200mV max)
o Three 5mA Current Regulators for Keypad
Lighting
I
2
C-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)
o Open/Short LED and Open-Circuit Diode
Detection
o Thermal-Shutdown and Output Overvoltage
Protection
o Ultra-Low 0.1µA Shutdown Current
o Tiny 2mm x 2mm, 16-Bump WLP Package
MAX8831
High-Efficiency, White LED Step-Up Converter
with I
2
C Interface in 2mm x 2mm WLP
________________________________________________________________
Maxim Integrated Products
1
19-4370; Rev 1; 7/09
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.
EVALUATION KIT
AVAILABLE
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.
MAX8831
High-Efficiency, White LED Step-Up Converter
with I
2
C Interface in 2mm x 2mm WLP
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
IN to GND ..............................................................-0.3V to +6.0V
V
DD
, COMP to GND.....................................-0.3V to (V
IN
+ 0.3V)
SDA, SCL to GND.......................................-0.3V to (V
DD
+ 0.3V)
OUT, LX, LED1–LED5 to GND................................-0.3V to +30V
I
LX
(Note 1) .....................................................................1.2A
RMS
PGND to GND .......................................................-0.3V to +0.3V
Operating Temperature Range ...........................-40°C to +85°C
Continuous Power Dissipation (T
A
= +70°C)
16-Bump, 2mm x 2mm WLP
(derate 8.2mW/°C above +70°C ambient)...................660mW
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering, reflow) ............................+260°C
ELECTRICAL CHARACTERISTICS
(V
IN
= 3.6V, V
GND
= V
PGND
= 0V, V
DD
= 1.8V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER CONDITIONS MIN TYP MAX UNITS
IN Supply Voltage 2.7 5.5 V
V
DD
Supply Voltage 1.6 5.5 V
IN Undervoltage Lockout
Threshold
2.4 2.6 V
IN Quiescent Current No load, 2MHz switching 1.5 mA
T
A
= +25°C 0.1 1
IN Shutdown Current V
DD
= GND
T
A
= +85°C 0.1
µA
T
A
= +25°C 0.1 1
V
DD
Standby Current V
SDA
= V
SCL
= V
DD
T
A
= +85°C 0.1
µA
T
A
= +25°C 2 5
IN Standby Current V
SDA
= V
SCL
= V
DD
T
A
= +85°C 2
µA
T
A
= +25°C 0.01 1
OUT Leakage Current V
IN
= V
OUT
= 5.5V, V
DD
= GND
T
A
= +85°C 0.1
µA
LED_ CURRENT REGULATORS
I
LED1
or I
LED2
= 25mA setting 200 mV
LED_ Current Regulator Dropout
Voltage (Note 2)
I
LED3
or I
LED4
or I
LED5
= 5.0mA setting 150 mV
T
A
= +25°C -2 +2
I
LED1
or I
LED2
= 25.25mA
setting
T
A
= -40°C to +85°C -5 +5
%
T
A
= +25°C -2 +2
LED_ Current Accuracy
I
LED3
or I
LED4
or I
LED5
= 5.0mA
setting
T
A
= -40°C to +85°C -5 +5
%
T
A
= +25°C 0.01 1
LED_ Leakage Current V
LED_
= 5.5V, V
DD
= GND
T
A
= +85°C 0.1
µA
LED_ Regulation Voltage 0.35 V
N-CHANNEL SWITCH
LX Current Limit 780 860 mA
LX On-Resistance I
LX
= 200mA 0.3 Ω
Note 1: LX has an internal clamp diode to PGND. Applications that forward bias this diode should take care not to exceed the power
dissipation limits of the device.
MAX8831
High-Efficiency, White LED Step-Up Converter
with I
2
C Interface in 2mm x 2mm WLP
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3.6V, V
GND
= V
PGND
= 0V, V
DD
= 1.8V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER CONDITIONS MIN TYP MAX UNITS
T
A
= +25°C 0.01 1
LX Leakage Current V
IN
= V
LX
= 5.5V, V
DD
= GND
T
A
= +85°C 0.1
µA
OSCILLATOR
Operating Frequency 1.8 2 2.2 MHz
Maximum Duty Cycle V
LED1
or V
LED2
= 0.2V 87 92 100 %
Minimum On-Time Skip mode 30 ns
COMP
Soft-Start Charge Current -20 µA
COMP Input Resistance to GND Step-up converter off 20 kΩ
I
2
C INTERFACE
SDA, SCL Logic Input High
Voltage
V
DD
= 1.6V to 5.5V
0.7 x
V
DD
V
SDA, SCL Logic Input Low
Voltage
V
DD
= 1.6V to 5.5V
0.3 x
V
DD
V
SDA Output Low Voltage I
SDA
= 3mA 0.03 0.4 V
T
A
= +25°C 0.01 1
SDA, SCL Logic Input Current V
IL
= 0V or V
IH
= 5.5V
T
A
= +85°C 0.1
µA
FAULT PROTECTION
Thermal Shutdown Temperature rising +160 °C
Thermal-Shutdown Hysteresis 20 °C
Output Overvoltage Threshold V
OUT
rising 28 30 V
Output Overvoltage Hysteresis 4V
Open LED_ Sense Voltage LED_ enabled, measured at LED_ 100 120 mV
Shorted LED_ Sense Voltage LED_ enabled, measured at LED_, V
OUT
= 10V
V
OUT
- 2.2V
V
OUT
- 0.7V
V
Open/Short LED Debounce Timer 16 ms
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P28

MAX8831EWE+T

Mfr. #:
Buy MAX8831EWE+T
Manufacturer:
Maxim Integrated
Description:
LED Lighting Drivers White LED Step-Up Converter
Lifecycle:
New from this manufacturer.
Delivery:
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