The present invention discloses a transformer used in a charger circuit,
in which the input side of the transformer is connected to an AC input
and PWM control circuit of the charger circuit, the output side of the
transformer is connected to a constant current and/or constant voltage
control circuit of the charger circuit. The AC input, PWM control
circuit, the constant current and/or constant voltage control circuit are
coupled through an optical coupling element, wherein the transformer
includes a main output winding and an auxiliary output winding, and the
auxiliary output winding is used to supply power for the optical coupling
element and the constant current and/or constant voltage control circuit.
The present invention further provides a high performance charger circuit
adopting the transformer described above for improving electromagnetic
compatibility, conversion efficiency and short circuit characteristic.