What This Mag45 RJ45 Jack Does on the Board
The TE Connectivity 1840872-1 is a single-port RJ45 jack from the Mag45 series — a family that integrates the magnetics into the connector body, so you don't need separate transformer modules on the PCB for 10/100 Base-T and AutoMDIX applications. This one is a 90° right-angle, through-hole mount part with the tab facing up, designed to sit at the board edge and take an Ethernet cable straight in.
What the Key Specs Mean for Your Fit
The 0.531" (13.49mm) height above board is the z-height you need to clear in the enclosure — measure from the PCB top to the inside of the lid or bezel before laying out the board.
Does It Need External Magnetics?
No — the Mag45 series integrates the magnetics inside the connector housing. The 4 cores per jack handle the transformer and common-mode choke functions for 10/100 Base-T. That saves board space and simplifies the BOM, but it also means the connector is taller than a plain RJ45 jack and the magnetics spec is fixed to the part number — you can't swap in a different transformer later.
The 1840872-1 and 1840872-2 are both single-port Mag45 RJ45 jacks with the same 90° right-angle orientation, through-hole mounting, and EMI finger shielding. The difference comes down to the LED configuration: the 1840872-1 does not contain an LED, while the 1840872-2 includes integrated LED indicators for link/activity status. If your design needs port status lights on the connector face, go with the 1840872-2; if you're routing those signals elsewhere on the board or using a separate LED array, the 1840872-1 saves the cost and routing of the unused LED pins.