Patent ID: 8450964

Claim:
A control circuit comprising: a battery charging circuit coupled to receive a solar cell voltage from a solar cell and a battery voltage from a rechargeable battery, wherein the battery charging circuit is configured to charge the rechargeable battery from the solar cell when the solar cell voltage is greater than the battery voltage; a driver circuit coupled to receive the battery voltage from the rechargeable battery; a driver enable circuit that enables the driver circuit entirely in response to the solar cell voltage becoming less than a first voltage; and an output terminal of the driver circuit configured to be coupled to a light source, wherein the driver circuit, when enabled, drives an output current to the output terminal, thereby developing an output voltage on the output terminal, and wherein the driver circuit includes a comparator coupled to receive the battery voltage and the output voltage, the comparator is configured to select a supply voltage for the driver circuit to be the larger of the battery voltage or the output voltage when the driver circuit is enabled.