The 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 operates
over a wide input voltage range of 4.6V to 28V with high
power-to-light efficiency. The device 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 pulse-width-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.
Key Features
Applications/Uses
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
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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