Catalog
Charge Pump Driver for 6 White LED LCD Backlights
Key Features
• Drives 6 LEDs from 2.6 V to 5.5 V (Li-Ion) input supply
• 1×/1.5×/2× fractional charge pump to maximize power efficiency
• 1% max LED current matching
• Up to 88% power efficiency over Li-Ion range
• Powers main and sub display LEDs with individual shutdown
• Package footprint only 9 mm2(3 mm × 3 mm)
• Package height only 0.75 mm
• Low power shutdown mode
• Shutdown function
• Soft-start limiting in-rush current
Description
AI
The ADM8845 uses charge pump technology to provide the power required to drive up to six LEDs. The LEDs are used for backlighting a color LCD display, having regulated constant current for uniform brightness intensity. The main display can have up to four LEDs, and the sub display can have one or two LEDs. The digital CTRL1 and CTRL2 input control pins control the shutdown operation and the brightness of the main and sub displays.To maximize power efficiency, the charge pump can operate in a 1×, 1.5×, or 2× mode. The charge pump automatically switches between 1×/1.5×/2× modes, based on the input voltage, to maintain sufficient drive for the LED anodes at the highest power efficiency.Improved brightness matching of the LEDs is achieved by a feedback pin to sense individual LED current with a maximum matching accuracy of 1%.ApplicationsCellular phones with main and sub displaysWhite LED backlightingCamera flash/strobes and movie lightsMicro TFT color displaysDSCPDAs
