Single Pair Ethernet

Keep the XTAL as close as possible to the IC. Where applicable connect the XTAL housing to GND. A via fence reduces coupling to the GND plane. An oscillator can be used alternatively.

Load capacitors should be low leakage and stable across temperature range (NP0). For the capacitive load (cload) the stray capacitance of the PCB and the IC pins should be considered:

C_L = (C₁*C₂) / (C₁+C₂) + C_stray

C_stray ≈ 3…6pF

100BASE-T1 Applications require a common mode choke for interference suppression in frequencies up to 200 MHz.

Although ethernet is an isolated interface, 1.5kV is not enough to protect from ESD. Super Speed TVS are needed to properly avoid damage to delicate parts. Avoid layer hops to prevent propagation of the ESD.

This Capacitor increases common mode rejection by balancing the center tap of the transformer.

Isolation of 1.5 kV AC is required by the standard, which makes MLCCs with only 2 kV insufficient.

This capacitor diverts common mode noise to Chassis Ground. Because of the capacitors dc blocking property, a rated voltage of 2 kV is chosen, to avoid inadvertent potential equalization and damaging of the component.

According to IEC 62368-1 Single Pair Ethernet requires an isolation of 1.5 kV. Our WE-STST transformer series combines excellent performance regarding return loss and mode conversion loss with a very compact size of only 4.5 x 3.2 mm.

These Capacitors extend the transformer bandwith and thus improve the return loss in low frequencies. As an alternative, a capacitor can be used at the center tap to block DC current from PoDL Application.

These Capacitors extend the transformer bandwith and thus improve the return loss in low frequencies. As an alternative, a capacitor can be used at the center tap to block DC current from PoDL Application.