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 11
Recommended by ENGICAM:
Diode array TVS, 4 CH, ESD, 3.3V
Wurth Elektronik 824013
Note:
for further details about PHY Protection reffer to file AN1718 of SMSC
D N :
3 0
