This part is a kind of semiconductor called EI-28.

Function of this product has General Power Transformer.

Manufacturers : Sumida Corporation

Image and pinout :

Some of the text within the PDF file :

General Power Transformer < Pin Type: EI Series> Type: EI-28 ◆ Product Description ・29.5×25.0mm Max.(L×W), 23.0mm Max. Height. ・Custom design is available. ◆ Feature ・Max. Operating frequency 300kHz. Max Operating power 51.0W(300kHz). ・Ideally used in Switching regulator, EL inverter and Power Factor Correction choke. ・RoHS Compliance ◆ Dimensions (mm) Adhes i ve φ0.8-±0.1 29 .5 MAX . 25 . 0 MA X . 2 3. 0 M AX . 7 .5 ±1. 0 17.5±0.5 ◆ Schematics (Bottom) 1.For General Transformer ⑤ ④ ⑥ S ⑦ S ⑧ ⑨ ⑩ 2.For PFC choke ⑤ S ④ ③ S ② S ① ⑥ ⑦ ⑧ ⑨ ⑩ S ③ S ② ① “ S” is winding start “ S” is winding start ◆ Specification (For General Transformer) Sample No. 3390-T144 ◆ Inductance (6-9) 1kHz/1V (m [ ... ]

EI-28 PDF Datasheet Download