Backlight Driver Eliminates Need for Processor in Portable Devices
Analog Devices Inc., a global leader in high-performance semiconductors for signal-processing applications, offers the ADP8870 white LED charge-pump backlight driver that lowers the power consumption of battery-operated handheld devices by up to 45% without compromising viewing quality. The ADP8870 combines three key functions: a programmable backlight LED charge-pump driver with inputs for a photo transistor to automatically control the LED brightness and a PWM (pulse-width modulation) input to manage the scale of the output current. This combination of features significantly reduces power use by automatically changing the current intensity based on the ambient lighting levels and the white content of the displayed image. By performing this function automatically, the ADP8870 eliminates the need for a processor to monitor the phototransistor, further reducing power requirements and simplifying the portable backlight design.
The ADP8870 controls up to seven LEDs either grouped together for backlight control or used independently for keypad illumination or indicator lighting. The fading of each LED is programmable, allowing the designer to customize the fade-in, fade-out, dim, and off times.