Lantronix
SESPM1040-541-LT-xx Install Guide
33772 Rev. F
Page
50
of
64
PoE Modes, Compliance, Standards and Troubleshooting
The switch is a Type 4 device (Class 8) that supports IEEE 802.3af/at/bt Power-over-Ethernet.
PoE History
PoE
first emerged to solve the problem of powering Voice over Internet Protocol (VoIP) phones. PoE gained
momentum in 2001 and 2002, when WAP makers, and other manufacturers took advantage of the technique.
IEEE 802.3af can use a single standard RJ45 connector and CAT 5 (or even CAT 3) cable.
PoE+ (PoE Plus)
provides extended support for new end devices with higher power requirements. The IEE
802.3at standard provides up to 30 W of power to include newer end devices such as IEEE 802.11n wireless
access points, surveillance cameras, etc.
PoE++ (IEEE 802.3bt)
: As manufacturers continued to advance the use of PoE, another option became available
for PoE with greater output. PoE++ delivers up to 90 watts of power using the 802.3bt standard. PoE++ is
delivered using 4 Pairs. PoE++ is ideal for IP surveillance cameras that require more throughput or a various
other equipment such as LCD displays, computer workstations, and biomedical equipment.
Minimum cable type
Cat5e; recommend Cat 6A cabling.
Passive
PoE
: Passive PoE describes Ethernet power sources (like PoE switches or PoE injectors) that send raw
unnegotiated energy down Ethernet cables to connected devices. The device connected to that cable will
receive the electricity, whether it is able to handle it or not. If using a Passive PoE, make sure you properly
understand the voltage requirement for your device before you plug it in.
PoE Standards Comparison
PoE Type 1 / PoE+ Type 2 / 802.3bt Type 3 / 802.3bt Type 4
Property
802.3af PoE
(Type 1)
802.3at PoE+
(Type 2)
802.3bt Type 3
802.3bt Type 4
Power Available at
PD
12.95 W
25.50 W
51 W
71 W
Max. Power from PSE 15.40 W
30.0 W
60 W
90 W
Voltage Range (at
PSE)
44.0 – 57.0 V
50.0 – 57.0 V
50.0 – 57.0 V
52.5 – 57.0 V
Voltage Range (at PD) 37.0 – 57.0 V
42.5 – 57.0 V
42.5 – 57.0 V
41.1 – 57.0 V
Max. current
350 mA
600 mA per mode
1200 mA
1371 mA
Max. cable resistance 20 ohms (Cat 3)
12.5 ohms (Cat 5)
6.25 ohms
6.25 ohms
Power management
3 power class levels
negotiated by
signature
4 power class levels
negotiated by
signature or 0.1 W
steps negotiated by
LLDP
3 power class
levels negotiated
by signature or
0.1 W steps
negotiated by
LLDP
0.1 W steps
negotiated by
LLDP