The ADP8870 combines a programmable backlight LEDcharge-pump driver with automatic phototransistor control ofthe brightness (LED current) and a PWM input to control thescale of the output current. This combination allows significantpower savings because it automatically changes the currentintensity based on the sensed ambient lighting levels and thedisplay image content. It performs this function automatically,eliminating the need for a processor to monitor the phototransistor.The light intensity thresholds are fully programmablevia the I²C interface.

The ADP8870 allows up to six LEDs to be independently driven upto 30 mA (maximum). An additional seventh LED can be driven to60 mA (maximum). All LEDs are individually programmable forminimum/maximum current and fade-in/fade-out times throughan I²C interface. These LEDs can also be combined into groupsto reduce the processor instructions during fade-in and fade-out.

Driving these components is a two-capacitor charge pumpwith gains of 1×, 1.5×, and 2×. This setup is capable of driving amaximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. A fullsuite of safety features, including short-circuit, overvoltage, andovertemperature protection, allows easy implementation of asafe and robust design. Additionally, input inrush currents arelimited via an integrated soft start combined with controlledinput-to-output isolation.

Applications

• Mobile display backlighting
• Mobile phone keypad backlighting
• RGB LED lighting
• LED indication
• General backlighting of small format displays

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.