Common mode filters (CMF) are filters that minimize common mode noise in differential transmission lines, power lines, and audio lines. They are used in non-automotive applications (USB, HDMI, Mipi, …) and automotive applications such as USB, CAN, CAN-FD, 100Base-T1, 1000Base-T1, LVDS, SerDes, ...
They're perfect for reducing common mode noise with frequencies ranging from a few megahertz to a few hundred megahertz while causing no signal degradation.
Why common-mode filters are needed in automotive applications?
ST’s common-mode filters for Automotive applications are qualified as per AEC-Q101 and are compliant with standards IEC 61000-4-2 and ISO 10605.
They have been designed with electrostatic discharge protection for 1 or 2 differential line pairs that attenuate common mode signals while providing enhanced communications performances.
Designed to avoid RF antenna desense in applications where the high-speed differential links generate radiated noise at frequencies received by the RF antenna, they’re specifically intended for nonshielded cables (UTP Unshielded Twisted Pair) often used in HDBaseT and 1G, 10G, or more automotive Ethernet (IEEE xxxxBase-T1) connectivity solutions for digital video and audio, Ethernet, and other control communications.
They’re useful in SerDes (serializer/deserializer) applications including FPD-link, GMSL, and MIPI A-PHY, DSI, or CSI to avoid radiation in several frequencies bands like vehicle-to-everything (V2X-5.9 GHz), wi-fi and Global Navigation Satellite System GNSS (GPS, Glonass, BeiDou, Galileo, and IRNSS) frequencies.
The automotive ECMF series is the key component for automotive applications to pass the following certifications:
- CISPR-25, international standard for radio disturbance characteristics
- 2004/104/EC European standard for radiated emission and immunity
- SAE J1113/41 for North America markets
Application:
Product types:
ST’s ECMF are available either in WLCSP package or DFN package to be compatible with industrial and automotive assembly requirements. Available in 2-lines or 4-lines, they offer an optimized flow-through footprint, with high common-mode attenuation of unwanted frequencies.
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Benefits:
- Improved receiver sensitivity by removing common-mode noise in useful antenna bandwidth
- Space and BOM savings by integrating both the ESD protection diodes and the common-mode filter
- Help to ensure CISPR-25, international standard for radio disturbance characteristics, 2004/104/EC European standard for radiated emission and immunity and SAE J1113/41 for North America markets
- Improved ESD clamping thanks to dual clamping structure (ESD diode and serial resistor of inductance)
- Better FIT (Failure In Time) compared to discrete ESD + CMF solution
- Low serial resistance to reduce eye-diagram distortion
- High reduction of parasitic elements through integration.
- Compatible with automotive assembly thanks to wettable flanks package suitable for AOI (Automatic Optical Inspection)
