Photovoltaic power source for portable electronic device

1. Field of the Invention A battery charging circuit for portable electronic devices including a photovoltaic cell for generating electrical current for charging of batteries. The charging circuit includes a state machine charge control circuit to selectively apply the electrical current generated by the photovoltaic cell to the batteries for charging and/or to the operational circuits of the portable electronic device for operation of the device. The photovoltaic cell, charge control circuit and operational circuits may be packaged in a number of alternative embodiments. In a first embodiment the photovoltaic cell and charge control circuit are integrated in a single circuit package. In a second, the various components are in separate circuit packages to enhance flexibility in design options. In a third embodiment, the charge control circuit is integrated with the operational circuits of the device. The charging circuit may be physically affixed to the portable device or may be electrically coupled to the device through a holder used to carry the device when not in use.