Filter design for single-pair Ethernet interface — Image source: Würth Elektronik
As a member of the SPE Industrial Partner Network initiative, Würth Elektronik promotes the use of Single Pair Ethernet in industrial applications. For safe use in industrial applications, Würth Elektronik has now published a circuit layout with transformers as galvanic isolation. The solution has an isolation of 1.5 kV/60 s and is therefore fully suitable for industrial applications, unlike previous circuits that use two 50 V capacitors as galvanic isolation.
By using only one pair of wires, the number of passive components on the PCB is considerably reduced. Together with the very compact connector, Single Pair Ethernet can save up to 75 % PCB space, compared to current Ethernet over RJ45. — Image source: Würth Elektronik
Würth Elektronik has published the first industrial SPE circuit that is fully compatible with the IEEE-802.3-signal requirements and the requirement of a 1.5 kV safety insulation according to IEC 62368-1. The filter solution is extremely compact and ensures signal stability of up to 40 m cable length for 100BASE-T1 or up to 1 000 m for 10BASE-T1. Würth Elektronik’s innovative approach: Instead of using capacitors, electrical isolation is achieved by means of a signal transformer. The WE-STST transmitter series is optimized for the signal bandwidth of Single Pair Ethernet and takes up very little space on the circuit board with only 4.5 × 3.2 mm. In addition to the WE-STST transmitter, a common mode choke, the WE-CNSW current-compensated data line filter, improves the EMC behavior already at frequencies from 1 MHz without negatively affecting the useful signal. A TVS diode (WE-TVS) provides ESD protection according to IEC 61000-4-2 up to 8 kV.
Further information on the industrial use of Singe Pair Ethernet can be found on the Würth Elektronik homepage and in this webinar recording on the topic “Single Pair Ethernet – Filter Design“. All passive components used in the layout developed by Würth Elektronik are available from stock. Free samples can be requested.