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 PackageApplicationNotebook Computer Displays
LCD TVs
LCD Monitors
Automotive DisplaysPinout
SpecificationsBATT to GND..........................................................-0.3V to +30V
BST1, BST2 to GND ...............................................-0.3V to +36V
BST1 to LX1, BST2 to LX2 ........................................-0.3V to +6V
GH1 to LX1 ..............................................-0.3V to (VBST1 + 0.3V)
GH2 to LX2 ..............................................-0.3V to (VBST2 + 0.3V)
VCC, VDD to GND .....................................................-0.3V to +6V
REF, ILIM to GND .......................................-0.3V to (VCC + 0.3V)
GL1, GL2 to GND .......................................-0.3V to (VDD + 0.3V)
CCI, CCV, LOT to GND ............................................-0.3V to +6V
IFB, ISEC, VFB to GND................................................-6V to +6V
SDA, SCL, SUS to GND............................................-0.3V to +6V
PGND to GND .......................................................-0.3V to +0.3V
Continuous Power Dissipation (TA = +70°C)
28-Pin Thin QFN (derate 20.84mW/°C above +70°C) ..1667mW
Operating Temperature Range .......................-40°C to +85°C
Junction Temperature....................................................+150°C
Storage Temperature Range .........................-65°C to +150°C
Lead Temperature (soldering, 10s) ...............................+300°C
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
DescriptionThe MAX8709B 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 MAX8709B operates over a wide input voltage range of 4.6V to 28V with high power-to-light efficiency. The MAX8709B also includes safety features that effectively protect against many single-point fault conditions including lamp-out and short-circuit faults.
The MAX8709B achieves 10:1 dimming range by "chopping"the lamp current on and off using a digital pulsewidth-modulation (DPWM) method. The minimum DPWM duty cycle of the MAX8709B is 12.5%. 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 MAX8709B is available in a space-saving 28-pin thin QFN package and operates over a -40°C to +85°C temperature range.
MAX8709B Data Sheet
