Power over Ethernet protection
PEP01-5841
A new Transil array to protect power supplies
Power over Ethernet eliminates the need for external power
supplies on the customer’s side as they are included in
routers and are able to deliver up to 30 W under 48 V
(POE+) according to IEEE 802.3af. Power is transported
using two pairs in an Ethernet cable. As for all cables, they
are subject to surges and must be protected against
electrostatic discharge (ESD) and electrical overstress
(EOS).
Key features
Key benefits
PEP01-5841
The PEP01-5841 embeds 4 protection units that are
fine tuned in voltage and current for POE applications,
and 4 capacitances to filter high-frequency
disturbances.
Temperature capability
The PEP01-5841 is specified with I
Rmax
= 1 µA at 85 °C
(telecommunication temperature) and 0.2 µA at 25 °C.
T
Jmax
is compliant with the industrial standard for tough
environments: 150 °C
Surge capability
To be compliant with IEC 61000-4-5 level 2 (1 kV),
the PEP01-5841 is specified at 24 A 8/20 µs and the
V
CL
has been improved to be compatible with 100 V
PMOS and PSE controller technologies.
V
BRmin
has been defined to take into account tolerance
on power supply voltage and can be calculated
whatever the temperature is using (aT):
V
BRmin @ TJ
= V
BRmin @ 25°C
x (1 +
aT
x (T
J
– 25))
Dynamic resistance (R
D
) is given to calculate V
CLmax
at
other current surge values, for instance at 12 A
(IEC 61000-4-5 level 1,500 V):
V
CLmax
= R
D
x I
PP
+ V
BRmax
V
CLmax
= 85.6 V
The PEP01-5841 is able to protect against ESD up to
30 kV according to IEC 61000-4-2.
Compliant with IEC 61000-4-5 level 2
(1 kV – 24 A 8/20 µs)
Compatible with PMOS and PSE controller voltages
(maximum clamping voltage: 100 V)
Low leakage current in telecommunication
temperature range
4 protection units/filtering in 1 S0-8 package
(55% space saving)
Target applications
Power over Ethernet (POE and POE+)
Package
The PEP01-5841 is packaged in an SO8 (28 mm²)
which provides 55% space saving versus 4 x SMA
(Transils) + 4 x 0306 capacitances.
www.st.com/protection
Relevant standards
As an Ethernet cable is a dataline, the impedance of the
IEC 61000-4-5 surge generator is 42
W.
Surge level is
either 500 V or 1 kV, leading to surge currents of 12 A or
24 A respectively (8/20 µs).
The second standard is IEC 61000-4-2, which defines
ESD surges.
State-of-the-art protection
Protection is achieved using the SMAJ58A and
SMBJ58A Transils specified with V
CLmax
= 121 V, which is
higher than the maximum admissible voltage of PMOS
and PSE controllers.
Application schematic
PSE
controller
- 48 V
PEP01-5841
© STMicroelectronics - April 2009 - Printed in Italy - All rights reserved
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Transil, Trisil and Transky are trademarks of STMicroelectronics. All other names are the property of their respective owners.
For more information on ST products and solutions,
visit
www.st.com
Order code: FLPEP010409
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