Transformer and power supply device including the same

A transformer, comprising:

• a magnetic core;
• a first coil unit disposed within the magnetic core and including a laminated board having layers laminated therein and conductive patterns for forming a primary coil, respective ones of the conductive patterns being disposed on the laminated layers;
• and
• a second coil unit including a conductive wire for forming a secondary coil spaced apart from the conductive patterns of the laminated board by an insulating distance,
• wherein the laminated board includes a first layer on which a conductive pattern is disposed, a second layer on which a shielding pattern is disposed, and a third layer on which a Vcc pattern for forming an induction current is disposed,
• wherein the conductive pattern, the shielding pattern, and the Vcc pattern of the laminated board are disposed around a through hole allowing a middle leg of the magnetic core to be inserted thereinto,
• wherein a maximum width of an edge of the shielding pattern is greater than a maximum width of an edge of the Vcc pattern, and
• wherein the first coil unit comprises a connector to electrically connect an external board and a stoppage protrusion,
• wherein the stoppage protrusion is disposed between a side wall of the magnetic core and the connector, disposed to correspond to the side wall of the magnetic core, and prevents insertion of the connector in a direction of the middle leg.