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.
