This part is a kind of semiconductor called ST12.

Function of this product has IR/RF Remote Control Encoder/Decoder IC.

Manufacturers : SunRom

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Some of the text within the PDF file :

ST12 CODEC – IR/RF Remote Control Encoder/Decoder IC 1. Overview ST12 CODEC is Radio Frequency and Infrared encoder/decoder IC for remote control applications having unique features and flexibility not available with other remote control encoder decoder ICs. ST12 is truly a single-chip remote control solution. Transmitter and Receiver can operate over Radio Frequency or Infrared having four address and eight data bits. Transmission and Reception over Infrared is achieved by commonly available Infrared LEDDetector and for RF any general purpose RF Transmitter-Receiver pair would suffice. The ST12 combines the functionality of both encoder and decoder in a single package with several unique features for enhanced operation and a reduced component count for transmitter a [ ... ]

ST12 PDF Datasheet Download