This part is a kind of semiconductor called 25TTS12S.

Function of this product has SURFACEMOUNTABLEPHASECONTROLSCR.

Manufacturers : InternationalRectifier

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Some of the text within the PDF file :

Previous Datasheet Index Next Data Sheet Bulletin I2117 25TTS..S SERIES SURFACE MOUNTABLE PHASE CONTROL SCR Description/Features The 25TTS..S new series of silicon controlled rectifiers are specifically designed for medium power switching and phase control applications. The glass passivation technology used has reliable operation up to 125° C junction temperature. Typical applications are in input rectification (soft start) and these products are designed to be used with International Rectifier input diodes, switches and output rectifiers which are available in identical package outlines. VT ITSM < 1.25V @ 16A = 250A VR/ VD = 1200V Output Current in Typical Applications Applications NEMA FR-4 or G10 glass fabric-based epoxy with 4 oz (140µm) copper Aluminum IMS, RthCA = 15°C/W A [ ... ]

25TTS12S PDF Datasheet Download