5.6.3 Phy Ethernet
When using an SMSC device, for each application an external transient protection is recommended , especially when the POE is used,
as shown in figure below. The schematic shows an example of a TVS suppression solution. This solution couples the energy
differentially into the two TVS diodes on each differential pair. For cases when the transient is across the TX+/- pair in the figure below,
the voltage is clamped at a value equivalent to the forward bias voltage across D1, plus the zener voltage of D2. This transient voltage
must be clamped at a voltage no
greater than 5V
. D3 and D4 act the same way when the transient is across the RX+/- differential pair.
The total capacitance seen by each differential pair must not exceed 50pF (25pF single ended).
Figure 9
Recommended by ENGICAM:
Diode array TVS, 4 CH, ESD, 3.3V
Wurth Elektronik 824013
Note:
for further details about PHY Protection please reffers to file AN1718 of SMSC
D N :
2 9
