An electrolytic capacitor and a ballast choke of a lighting circuit, are
disposed on a first face of a circuit board facing a base, and a
one-package switch of the lighting circuit is disposed on a second face,
facing a fluorescent lamp. The one-package switch comprises field effect
transistors contained in a single package and serve as two inverter
switches for driving the fluorescent lamp. The one-package switch is a
generally rectangular SMD with dimensions of not more than 6 mm
respectively in length and width and mounted on the second face of the
circuit board by means of terminals of the one-package switch. The
one-package switch enhances heat dissipation properties of the circuit,
enables the reduction of its dimensions, and increases the mounting
efficiency.