MAXIM MAX8785AETI+T

The LCD enclosures and cold cathode fluorescent lamps (CCFLs) used in notebook computers and portable electronic displays are becoming increasingly narrow, requiring a slim CCFL power supply. Recent advances in piezoelectric transformers (PZT) have made it possible to develop smaller, more efficient, and safer backlight inverters for portable displays. Compared to magnetic transformers, piezoelectric transformers demonstrate superior performance in efficiency, EMI requirements, human safety, and form factor. The MAX8785A is a full-bridge CCFL controller for PZT-based backlight power supplies. The full-bridge topology provides high spectral purity sinusoidal drive, which helps the PZT efficiently convert electrical energy to mechanical energy and back.

• Feed-forward control architecture for excellent line and load regulation while maintaining a relatively constant switching frequency
• Protection against open lamp, secondary short circuit, lamp arc, and secondary overvoltage, with adjustable timeout
• Guaranteed lamp ignition via high-to-low switching frequency sweep
• 10:1 dimming range using digital pulse width modulation (DPWM)
• CCFL brightness settable via analog voltage on CNTL pin or external signal at LSYNC
• Maximum switching frequency and DPWM frequency adjustable via external resistor
• Gate drivers capable of driving high-power MOSFETs commonly used in high-power CCFL applications
• Internal 5.35V linear regulator powering MOSFET drivers and most internal circuitry
• Thin 28-pin QFN package, operating temperature range -40°C to +85°C

• Notebook LCD
• LCD TVs and monitors