MAX8790AETP+X01 Maxim Integrated, MAX8790AETP+X01 Datasheet
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MAX8790AETP+X01
Manufacturer Part Number
MAX8790AETP+X01
Description
LED Lighting Drivers Six-String White LED Driver
Manufacturer
Maxim Integrated
Datasheet
1.MAX8790AETPX01.pdf
(23 pages)
Specifications of MAX8790AETP+X01
Rohs
yes
Input Voltage
4.5 V to 26 V
Maximum Supply Current
2 mA
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
Power Dissipation
1349 mW
The MAX8790A is a high-efficiency driver for white light-
emitting diodes (LEDs). It is designed for large liquid-
crystal displays (LCDs) that employ an array of LEDs as
the light source. A current-mode step-up controller drives
up to six parallel strings of multiple series-connected
LEDs. Each string is terminated with ballast that achieves
±1.5% current regulation accuracy, ensuring even bright-
ness for all LEDs. The MAX8790A has a wide input-volt-
age range from 4.5V to 26V, and provides a fixed 20mA
or adjustable 15mA to 27mA full-scale LED current.
The MAX8790A has two dimming control modes to
enable a wide variety of applications. In direct DPWM
mode, the LED current is directly turned on and off by a
PWM signal. In analog dimming mode, an internal
phase-locked loop (PLL) circuit translates the PWM sig-
nal into an analog signal and linearly controls the LED
current down to 12.5%. Below 12.5%, digital dimming is
added to allow lower average LED current down to 1%.
Both control methods provide 100:1 dimming range.
The MAX8790A has multiple features to protect the con-
troller from fault conditions. Separate feedback loops limit
the output voltage if one or more LEDs fail open or short.
The controller features cycle-by-cycle current limit to pro-
vide consistent operation and soft-start capability. A ther-
mal-shutdown circuit provides another level of protection.
The step-up controller uses an external MOSFET, which
provides good efficiency and allows for scalable output
power and maximum operating voltage. Low feedback
voltage at each LED string (450mV) helps reduce
power loss. The MAX8790A features selectable switch-
ing frequency (500kHz, 750kHz, or 1MHz), which
allows trade-offs between external component size and
ope-rating efficiency.
The MAX8790A is available in a thermally enhanced,
lead-free, 20-pin, 4mm x 4mm, Thin QFN package.
19-0989; Rev 0; 10/07
+ Denotes a lead-free package.
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.
MAX8790AETP+ -40°C to +85°C
PART
Current Balancing for LCD Panel Applications
Notebook, Subnotebook, and Tablet Computer
Displays
Automotive Systems
Handy Terminals
TEMP RANGE PIN-PACKAGE
________________________________________________________________ Maxim Integrated Products
Six-String White LED Driver with Active
Ordering Information
General Description
20 Thin QFN
(4mm x 4mm)
Applications
T2044-3
CODE
PKG
o Drives Six Parallel Strings with Multiple Series-
o ±1.5% Current Regulation Accuracy Between
o Low 450mV Feedback Voltage at Full Current
o Step-Up Controller Regulates the Output Just
o Full-Scale LED Current Adjustable from 15mA to
o Wide 100:1 Dimming Range
o Programmable Dimming Control: Direct DPWM or
o Built-In PLL for Synchronized Dimming Control
o Open and Short LED Protections
o Output Overvoltage Protection
o Wide Input Voltage Range from 4.5V to 26V
o External MOSFET Allows a Large Number of LEDs
o 500kHz/750kHz/1MHz Switching Frequency
o Small, 20-Pin, 4mm x 4mm Thin QFN Package
Pin Configuration appears at end of data sheet.
C
IN
Connected LEDs per String
Strings
Improves Efficiency
Above the Highest LED String Voltage
27mA, or Preset 20mA
Analog Dimming
per String
V
IN
N.C.
N.C.
0.1μF
SHDN
V
FSET
ISET
BRT
OSC
CPLL
CCV
ENA
EP
CC
MAX8790A
Simplified Operating Circuit
IN
GND
EXT
FB2
FB3
FB4
FB5
FB6
FB1
CS
OV
L1
N1
D1
Rs
R2
R1
V
OUT
Features
1