Patent ID: 7109465

Claim:
A method of illuminating a display on a battery powered system, comprising: converting ambient light energy into an electrical signal with a Gallium Arsenide Phosphate (GaAsP) photodiode; accessing said electrical signal from said GaAsP photodiode via a node on an integrated circuit device; amplifying said electrical signal from said GaAsP photodiode with an amplifier in said integrated circuit device; filtering said electrical signal from said GaAsP photodiode with a low pass filter in said integrated circuit device, wherein said filtering prevents a flicker effect on said signal from flickering ambient light conditions; comparing said amplified, filtered electrical signal to a threshold level with a comparator in said integrated circuit device, said threshold level corresponding to a pre-determined level of ambient light; generating an output signal from said comparator indicating whether said ambient light is greater than or less than said threshold level; driving and buffering said output signal at a driver stage in said integrated circuit device, wherein said driving and buffering generates a signal compatible with voltage and drive levels required for digital logic; direct coupling said output signal with a processor, wherein said processor comprises digital logic circuitry; activating an illumination source if said ambient light is less than said threshold level, wherein said activation is performed by said processor.