EET

LED backlight driver cuts current requirements in half

The ADP8860 features ambient light sensing, a highly programmable register set, and sophisticated fading and dimming options that reduce backlight power dissipation by up to 50 percent. This flexible architecture simplifies the system designer’s objective to optimize power management in a broad range of low-power, low-voltage products that require backlighting for small-format displays and/or keypads found in consumer, medical, industrial and instrumentation electronics devices.

The ADP8860 combines a programmable, backlight LED charge pump driver with automatic phototransistor control. This combination allows for significant power savings because it changes the current intensity in office and dark ambient light conditions. By performing this function automatically, it eliminates the need for a processor to monitor the phototransistor.

Light intensity thresholds are fully programmable via the I2C interface. A second phototransistor input, with dedicated comparators, improves the ambient light detection levels for various operating conditions.

The ADP8860 allows as many as six LEDs to be independently driven up to 30 mA; a seventh LED can be driven to 60 mA. All LEDs are programmable for minimum/ maximum current and fade in/out times via the I2C interface. These LEDs can also be combined into groups to reduce the processor instructions during fade in/out. Driving this entire configuration is a two-capacitor charge pump with gains of 1x, 1.5x, and 2x. This setup is capable of driving a maximum IOUT of 240 mA from a supply of 2.5 to 5.5 V. The device includes a variety of safety features including short circuit, over-voltage, and over-temperature protection.

Additionally, input inrush currents are limited via an integrated soft start combined with controlled input to output isolation. The ADP8860 is available in two package types: either a compact 2 x 2.4 x 0.6 mm WLCSP (wafer level chip scale package) or a small LFCSP (lead frame chip scale package). For more information, visit Analog Devices.



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