What the 300 Ohm impedance means for your differential signal pair
The ACM2520-301-2P-T002: This is a common-mode choke, not a simple ferrite bead — it targets differential signal pairs (USB, CAN, LVDS, audio lines) where common-mode noise rides on both lines equally. The 300 Ohms at 100 MHz impedance attenuates that common-mode current while leaving the differential signal intact. Rated for 20 V DC and 400 mA continuous, with a maximum DCR of 350 mOhm — the voltage drop across the winding at full current is 140 mV, which matters if the downstream receiver has a tight common-mode input range.