This part is a kind of semiconductor called MAX3490.

Function of this product has 3.3V-Powered / 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers.

Manufacturers : Maxim

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Some of the text within the PDF file :

AVAILABLE MAX3483/MAX3485/MAX3486/ MAX3488/MAX3490/MAX3491 3.3V-Powered, 10Mbps and Slew-Rate-Limited True RS-485/RS-422 Transceivers _______________General Description ____________________________Features The MAX3483, MAX3485, MAX3486, MAX3488, MAX3490, and MAX3491 are 3.3V, low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. The MAX3483 and MAX3488 feature slew-rate-limited drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission at data rates up to 250kbps. The partially slew-rate-limited MAX3486 transmits up to 2.5Mbps. The MAX3485, MAX3490, and MAX3491 transmit at up to 10Mbps. Drivers are short-circuit current limited and are protected against excessive po [ ... ]

MAX3490 PDF Datasheet Download