This part is a kind of semiconductor called BT139-800.

Function of this product has Triacs.

Manufacturers : Inchange Semiconductor

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Some of the text within the PDF file :

INCHANGE Semiconductor isc Triacs isc Product Specification BT139-800 FEATURES ·With TO-220 package ·Glass passivated triacs in a plastic envelope, for use in applications requiring high bidirectional transient and blocking voltage capability and high thermal cycling performance. Typical applications include motor control, industrial and domestic lighting,heating and static switching. ABSOLUTE MAXIMUM RATINGS(Ta=25℃) SYMBOL PARAMETER VDRM Repetitive peak off-state voltage VRRM Repetitive peak off-state voltage IT(RMS) RMS on-state current (full sine wave) ITSM Non-repetitive peak on-state current tp=20ms PGM Peak gate power dissipation PG(AV) Average gate power dissipation Tj Operating junction temperature Tstg Storage temperature ELECTRICAL CHARACTERISTICS (TC=25℃ unle [ ... ]

BT139-800 PDF Datasheet Download