Common mode noise suppression for signal lines
The TDK ACM2012H-381-2P-T05 is a 2-line common mode filter from the ACM-H series, designed to suppress conducted EMI on signal lines. It presents 380 Ohms of impedance at 100 MHz, the standard frequency for common mode noise attenuation on data interfaces like USB, HDMI, or LVDS. Rated for 300 mA continuous current with a maximum DC resistance of 500 mOhm, the filter introduces a voltage drop of 150 mV at full rated current — a figure to include in the signal margin budget for low-voltage differential pairs. The 20 VDC voltage rating covers most common signal rail voltages (3.3 V, 5 V, 12 V) with ample margin, but does not suit 24 V or 48 V power buses.