What 120 ohms at 100 MHz means on a signal line
The ACM2012-121-2P-TL002 is a 2-line common mode filter from TDK's ACM series, packaged in an 0805 footprint with a 4-pad layout for differential signal pairs. Its core spec is 120 ohms impedance at 100 MHz — this is the common-mode attenuation point for noise on USB, HDMI, LVDS, or CAN bus lines where the differential signal itself passes through unaffected while common-mode noise above that frequency is shunted. Rated for 370 mA continuous current with a maximum DC resistance of 220 milliohms, the insertion loss on the signal stays under 0.1 dB at low frequencies — the DCR is the thermal limit, not the magnetic saturation point, so the filter handles the full current rating without impedance roll-off.
0805 footprint and board integration
The 50 VDC rating covers signal-line isolation for most low-voltage differential interfaces. Surface-mount assembly with Tape & Reel packaging supports standard pick-and-place throughput.
Obsolete — sourcing reality for this TDK filter
TDK has marked the ACM2012-121-2P-TL002 as obsolete. No official successor order code is recorded in the lifecycle data, meaning a direct drop-in replacement from TDK's current catalog is not documented — the buyer's best path is independent distribution inventory or a parametric search for a 2-line 0805 common-mode filter with matching impedance and current rating. No pin-compatible second-source is listed on the official record, so a board-level qualification is advised if substituting from another manufacturer's 0805 common-mode choke family.