120 Ohms at 100 MHz — the common-mode stopband for signal lines
The TDK ACM2012E-121-2P-T00 is a two-line signal-line common-mode filter from the ACM-E series, delivering 120 Ohms impedance at 100 MHz — the standard reference frequency for EMI suppression on differential pairs and I/O lines.
Obsolete — sourcing through independent channels
TDK has marked the ACM2012E-121-2P-T00 as obsolete. For a BOM already qualified to this footprint and impedance target, the existing stock is the procurement path; there is no pin-compatible drop-in replacement from TDK with the same 120 Ohm @ 100 MHz characteristic in the ACM-E series.
0805 footprint, horizontal 4-pad — fits standard signal-line layouts
The two-line construction is designed for differential signal pairs — USB, CAN, LVDS, or Ethernet — where common-mode noise on the pair needs attenuation without affecting the differential signal.