Low-Cost, SMBus, CCFL Backlight Controller

Active: In Production.

The MAX8759 integrated cold-cathode fluorescent lamp (CCFL) inverter controller is designed to drive CCFLs using a full-bridge resonant inverter. The resonant operation 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 regulation (±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 system 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 maximum efficiency and directly drives four external n-channel 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.

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