19-3874; Rev 1; 2/06
Low-Cost, SMBus, CCFL Backlight Controller
General Description
The MAX8759 integrated cold-cathode fluorescent lamp
(CCFL) inverter controller is designed to drive CCFLs
using a full-bridge resonant inverter. The resonant opera-
tion ensures reliable striking and provides near-sinusoidal
waveforms over the entire input range. The controller
operates over a wide input-voltage range of 4.5V to 28V
with high power to light efficiency. The device also
includes safety features that effectively protect against
single-point fault conditions such as lamp-out, secondary
overvoltage, and secondary short-circuit faults.
The MAX8759 provides accurate lamp-current regula-
tion (±2.5%) for superior CCFL inverter performance.
The lamp current is adjustable with an external resistor;
10:1 dimming range can be achieved by turning the
CCFL on and off using a digital pulse-width modulation
(DPWM) method, while maintaining the lamp-current
constant. The MAX8759 provides three mechanisms for
controlling brightness: 2-wire SMBus™-compatible
interface, external ambient-light sensor (ALS), or sys-
tem PWM control. The MAX8759 supports Intel display
power-saving technology (DPST) to maximize battery
life. The device includes two lamp-current feedback
input pins that support dual-lamp applications with a
minimum number of external components.
The MAX8759 controls a full-bridge inverter for maxi-
mum efficiency and directly drives four external n-chan-
nel power MOSFETs. An internal 5.35V linear regulator
powers the MOSFET drivers and most of the internal
circuitry. The MAX8759 is available in a space-saving,
28-pin, thin QFN package and operates over a -40°C to
+85°C temperature range.
Features
♦
Accurate Dimming Control Using SMBus, PWM
Interface, or Ambient Light Sensor
♦
10:1 Dimming Range with 256-Step Resolution
♦
Resonant-Mode Operation
Longer Lamp Life with Near Sinusoidal Lamp-
Current Waveform
Guaranteed Striking Capability
High-Power-to-Light Efficiency
♦
Wide Input-Voltage Range (4.5V to 28V)
♦
Input Feed-Forward for Excellent Line Rejection
♦
±2.5% Lamp-Current Regulation
♦
Adjustable 1.5% Accurate DPWM Frequency
♦
Dual Lamp-Current Feedback Inputs
♦
Comprehensive Fault Protection
Secondary Voltage Limiting
Primary Current Limit with Lossless Sensing
Lamp-Out Protection with Adjustable Timeout
Secondary Short-Circuit Protection
♦
Small 28-Pin, 5mm x 5mm, Thin QFN Package
MAX8759
Minimal Operating Circuit
Applications
Notebooks
LCD Monitors
Automotive Infotainment
MAX8759
Ordering Information
PART
MAX8759ETI+
TEMP RANGE
-40°C to +85°C
PIN-
PACKAGE
28 Thin QFN-EP*
5mm
×
5mm
PKG
CODE
T2855-6
+
Denotes lead-free package.
*EP
= Exposed pad.
Pin Configuration appears at end of data sheet.
SMBus is a trademark of Intel Corp.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
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