Rainbow Electronics MAX8709 - Manual

General Description
The MAX8709 integrated backlight controller is optimized
to drive cold-cathode fluorescent lamps (CCFLs) using a
resonant full-bridge inverter architecture. The resonant
operation maximizes striking capability and provides
near-sinusoidal waveforms over the entire input range to
improve CCFL lifetime. The controller operates over a
wide input voltage range of 4.6V to 28V with high power-
to-light efficiency. The device also includes safety fea-
tures that effectively protect against many single-point
fault conditions including lamp-out and short-circuit faults.
The MAX8709 achieves 10:1 dimming range by “chop-
ping” the lamp current on and off using a digital pulse-
width-modulation (DPWM) method. The brightness is
controlled with a 2-wire SMBus™-compatible interface.
The device directly drives the four external N-channel
power MOSFETs of the full-bridge inverter. An internal
5.3V linear regulator powers the MOSFET drivers, the
DPWM oscillator, and most of the internal circuitry. The
MAX8709 is available in a space-saving 28-pin thin QFN
package and operates over a -40°C to +85°C temp-
erature range.
Applications
Notebook Computer Displays LCD TVs
LCD Monitors Automotive Displays
Features
♦ Synchronized to Resonant Frequency
Longer Lamp Life
Guaranteed Striking Capability
High Power-to-Light Efficiency
♦ Wide Input Voltage Range (4.6V to 28V)
♦ Feed Forward for Excellent Line Rejection
♦ SMBus Dimming Control Interface
♦ 10:1 Dimming Range
♦ Guaranteed 200Hz to 220Hz DPWM Frequency
♦ Secondary Voltage Limit Reduces Transformer
Stress
♦ Adjustable Lamp-Out Protection with 1s Timer
♦ Secondary Current Limit Protects Against High-
Voltage Short Circuits to Ground
♦ Small 5mm x 5mm Thin QFN Package
MAX8709
High-Efficiency CCFL Backlight
Controller with SMBus Interface
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
SCL
SDA
SUS
CCI
CCV
BATT
GND
LOT
REF
ILIM
V CC
V DD
BST2
BST1
GH1
LX1
LX2
GL1
PGND
GL2
GH2
VFB
ISEC
IFB
MAX8709
V IN
Minimal Operating Circuit
19-3177; Rev 0; 1/04
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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE PIN-PACKAGE
MAX8709ETI -40°C to +85°C 28 Thin QFN 5mm x 5mm
SMBus is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.