Disclosed is an LED lamp system designed to fit into a fluorescent lamp fixture and to utilize a fluorescent lamp power supply contained in the fixture and receiving power from AC mains. The LED lamp system includes an LED driver which comprises a power factor corrected driver circuit for achieving a power factor of at least about 0.8. The LED driver further comprises a current control circuit, responsive to the presence of a three-wire magnetic ballast in the fluorescent lamp power supply, for increasing the LED operating current above the nominal rated LED operating current and to a level sufficient to achieve power factor of the LED driver of at least about 0.8.