MAX8847Y

19-5196; Rev 0; 4/10 www.DataSheet4U.com TION KIT EVALUA BLE A IL A V A High-Performance Negative Charge Pump for 6 White LEDs in 3mm x 3mm Thin QFN General Description The MAX8847Y/MAX8847Z negative charge pumps drive up to 6 white LEDs with regulated constant current for display backlight applications. By utilizing an inverting charge pump and extremely low-dropout adaptive current regulators, these ICs achieve very high efficiency over the full 1-cell Li+ battery voltage range even with large LED forward voltage mismatch. The 1MHz fixedfrequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. The MAX8847Y/MAX8847Z include thermal shutdown, open- and short-circuit protection. The MAX8847Y/MAX8847Z support independent LED on/off and dimming control. The MAX8847Z has PWM dimming control for LED1–LED6. The MAX8847Y has PWM dimming control for LED1–LED4 and serial-pulse dimming control for LED5 and LED6. The serial-pulse dimming ranges are pseudo-logarithmic from 24mA to 0.1mA and off in 32 steps. All devices include a temperature derating function to safely allow bright 24mA fullscale output current while automatically reducing current gradually to protect LEDs at high ambient temperatures above +60°C. The MAX8847Y/MAX8847Z are available in 16-pin, 3mm x 3mm thin QFN packages. S Negative 1x/1.5x Charge Pump S Adaptive Current Regulators S Independent Voltage Supply for Each LED S 24mA to 0.1mA Ser...