This part is a kind of semiconductor called LF9203.

Function of this product has 100/1000BASE-T TRANSFORMER MODULES.

Manufacturers : Delta Electronics

Image and pinout :

Some of the text within the PDF file :

100/1000BASE-T TRANSFORMER MODULES Networking Components LF 92 02 ELECTRICAL CHARACTERISTICS @25 C Rise Time & Fall Time @5.0ns (Max), Hi-Pot Test @60Sec, 1500Vrms, OCL @8mA DC Bias 350uH (Min) Model Insertion Loss (dB Max) 1-100 100-125 1-30 MHz o Return Loss (dB Min) 40 50 60-80 100 MHz Cross Talk (dB Min) 30 60 MHz 100 Com. To Com. Rejection Ratio (dB Min) 1-100 MHz Diff. To Com. Mode Rejection (dB Min) 1-60 MHz 60-100 Turns Ratio TX/RX ( 5%) 1 MHz LF9202 LF9203 -1.0 -1.0 -1.2 -1.2 -18 -14.5 -13.5 -12 -18 -14.5 -13.5 -12 -10 -10 -45 -45 -40 -40 -35 -35 -30 -30 -40 -40 -30 -30 1:1 / 1:1 1:1 / 1:1 MECHANICAL CONSTRUCTION A 24 13 SCHEMATICS LF9202 2 1 3 24 23 22 21 20 19 18 17 16 15 14 13 LF920* 1 12 B D 5 4 6 DATE CODE E K F 8 7 9 11 10 12 I J C G H LF9203 [ ... ]

LF9203 PDF Datasheet Download