Patent ID: 7696851

Claim:
A transformer positioned on a circuit board, the transformer comprising: a core assembly; and a bobbin comprising a first winding frame to wrap primary winding coils thereon, a first winding chassis to receive the first winding frame therein, a pair of second winding chassis positioned at two opposite ends of the bobbin, a pair of second winding frames received in the pair of second winding chassis to wrap secondary winding coils thereon, and a receiving hole extending through the pair of second winding chassis and the first winding frame, wherein each of the pair of second winding frames comprises a plurality of pins mounted in the circuit board to fix the transformer on the circuit board, and a through hole communicating with the receiving hole to receive the core assembly, and wherein the first winding chassis comprises a pair of first sidewalls, and wherein the first winding frame is positioned between the pair of second winding chassis; wherein first terminals of the primary winding coils creep over one of the pair of first sidewalls of the first winding chassis along a first direction to be attached to the circuit board, and wherein second terminals of the secondary winding coils are wrapped, in a second direction different from the first direction, on the pins of the second winding frame to be attached to the circuit board.