a power factor correction (PFC) circuit for converting a received alternating current (AC) signal to a direct current (DC) signal;

a power stage circuit connected to the PFC circuit, for converting the DC signal to another AC signal;

an isolation transformer having a primary winding and at least a secondary winding; wherein the primary winding of the isolation transformer is connected to the power stage circuit, for isolating the received AC signal from the light source module;

an inverter circuit, connected to the secondary winding of the isolation transformer, for converting an AC signal output from the isolation transformer to an appropriate signal to drive the light source module; and

a PWM controller, connected to the power stage circuit, for controlling output from the power stage circuit;

wherein the inverter circuit comprises:

a plurality of transformers; wherein each of the transformers has at least a primary winding, a first secondary winding and a second secondary winding; and

a plurality of capacitors, correspondingly connected between high and low terminals of the first secondary windings of the transformers, and connected between high and low terminals of the second secondary windings of the transformers;

wherein high terminals of the primary windings of the transformers are jointly connected to a high terminal of the secondary winding of the isolation transformer, low terminals of the primary windings of the transformers are jointly connected to a low terminal of the secondary winding of the isolation transformer, high terminals of the first and the second secondary windings of the transformers are respectively connected to a lamp, and low terminals of the first and the second secondary windings of the transformers are grounded.