Display and keypad backlight management for portable electronic devices

This invention is a portable electronic device including a display, an input device, a lighting circuit, a light sensor and a control circuit. The lighting circuit includes a light source to illuminate the display and the input device. The light sensor determines the ambient lighting conditions about the display and/or the input device and generates an ambient lighting signal based on the ambient lighting conditions. The control circuit is coupled to the lighting circuit and the light sensor and has a delayed operation mode in which a first activation of the input device illuminates the display without performing any other operation of the device and a second activation of the input device performs an operation of the device other than illuminating the display. The control circuit of the portable electronic device may receive a reverse bias signal generated by the lighting circuit when incident with ambient lighting about the user interface to supplement or eliminate the light sensor.