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8 pin RJ45 (8P8C) female connector layout
Разъем 8 pin RJ45 (8P8C) female
Power over Ethernet is a technology that allows IP telephones, wireless LAN Access Points, security network cameras and other IP-based terminals to receive power, in parallel to data, over the existing CAT-5 Ethernet infrastructure without the need to make any modifications. Described by IEEE 802.3af standard.

PoE integrates data and power on the same wires, while keeping the structured cabling safe and not interfering with concurrent network operation. PoE delivers 44-57v of DC power over unshielded twisted-pair wiring for terminals consuming up to 25 watts, depending on the version of the standard in use. There are several common techniques for transmitting power over Ethernet cabling; two of them have been standardized by the IEEE 802.3 committee. Power may be transmitted on the unused (spare) conductors of a cable, since only two of the four pairs are needed for the commonly used 10Mbit/s–100Mbit/s physical layers (Alternative B) or power may be transmitted on the data conductors by applying a common-mode voltage to each pair (Alternative A). 

The IEEE standards for PoE require category 5 cable or better for high power levels but allow using category 3 cable if less power is required. Power is supplied in common mode over two or more of the differential pairs of wires found in the Ethernet cables and comes from a power supply within a PoE-enabled networking device such as an Ethernet switch or can be injected into a cable run with a midspan power supply. A midspan power supply, also known as a PoE power injector, is an additional PoE power source that can be used in combination with a non-PoE switch.

Standards-based Power over Ethernet is implemented following the specifications in IEEE 802.3af-2003. A phantom power technique is used to allow the powered pairs to also carry data. This permits its use not only with 10BASE-T and 100BASE-TX, which use only two of the four pairs in the cable, but also with 1000BASE-T (gigabit Ethernet), which uses all four pairs for data transmission. This is possible because all versions of Ethernet over twisted pair cable specify differential data transmission over each pair with transformer coupling; the DC supply and load connections can be made to the transformer center-taps at each end. Each pair thus operates in common mode as one side of the DC supply, so two pairs are required to complete the circuit. The polarity of the DC supply may be inverted by crossover MDI-X cables; the powered device must operate with either pair: spare pairs 4–5 and 7–8 or data pairs 1–2 and 3–6. Polarity is required on data pairs, and ambiguously implemented for spare pairs, with the use of a diode bridge.

IEEE 802.3af standard POE pinout:

Pins at switch T568A color T568B color mode B        mode A        mode A 
Pin 1
White/green stripe

White/orange stripe
  DC + DC -
Pin 2
Green solid

Orange solid
  DC + DC -
Pin 3
White/orange stripe

White/green stripe
  DC − DC +
Pin 4
Blue solid

Blue solid
DC +    
Pin 5
White/blue stripe

White/blue stripe
DC +    
Pin 6
Orange solid

Green solid
  DC − DC +
Pin 7
White/brown stripe

White/brown stripe
DC −    
Pin 8
Brown solid

Brown solid
DC −    

IEEE Std 802.3-2015 table 33-2 also allows PSE side Alternative A (MDI-X) with polarity reversed from Alternative A (MDI).

The original IEEE 802.3af-2003 PoE standard devices provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA) to each device.

The newer PoE+  IEEE 802.3at-2009 PoE standard provides up to 25.5 W of power. Some vendors have announced products that offer up to 51 W of power over a single cable by utilizing all four pairs in the Category 5 cable.

PoE parameters
Property 802.3af (802.3at Type 1)PoE 802.3at Type 2 PoE+ 802.3bt Type 3 4PPoE 802.3bt Type 4
Power available at PD 12.95 W 25.50 W 51 W 71 W
Maximum power delivered by PSE 15.40 W 30.0 W 60 W 100 W
Voltage range (at PSE) 44.0–57.0 V 50.0–57.0 V 50.0–57.0 V 52.0–57.0 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
Maximum current Imax 350 mA 600 mA 600 mA per pair 960 mA per pair
Maximum cable resistance per pairset 20 Ω (Category 3) 12.5 Ω (Category 5) 12.5 Ω 12.5 Ω
Power management Three power class levels negotiated by signature Four power class levels negotiated by signature or 0.1 W steps negotiated by LLDP Three power class levels negotiated by signature or 0.1 W steps negotiated by LLDP 0.1 W steps negotiated by LLDP
Supported cabling Category 3 and Category 5 Category 5 Category 5 Category 5
Supported modes Mode A (endspan), Mode B (midspan) Mode A, Mode B Mode A, Mode B, 4-pair mode 4-pair mode

POE proprietary pinouts:

  Ethernet RJ-45 connector pin number  
Source Voltage 1 2 3 4 5 6 7 8 Load Voltage DC Load Connector  
IEEE 802.3af
using data pairs
48 V DC, protected RX, DC+ RX, DC+ TX, DC- spare spare TX, DC- spare spare (embedded) Industry Standard for active PoE
IEEE 802.3af
using spare pairs
48 V DC, protected RX RX TX DC+ DC+ TX DC- DC- (embedded) Industry Standard for passive PoE
Intel, Symbol, Orinoco Usually
12 or 24 V DC
RX RX TX DC+ DC+ TX DC- DC- (embedded) Most Brands of PoE
(OLD old standard)
48 V DC RX RX TX DC- DC- TX DC+ DC+ (embedded) Older Cisco polarity is
(NEW old standard)
48 V DC RX RX TX DC+ DC+ TX DC- DC- (embedded) New Cisco is IEEE compliant

Cisco   (very unusual)

28 V DC DC+ DC- TX n.c. n.c. TX RX RX (embedded) Seen on Cisco 7936 conference station, also worked with Polycom SoundStation IP 4000 with 19V source power
D-Link (Adapter) 48 V DC RX RX TX DC+ DC+ TX DC- DC-

5VDC @ 2.5A
or 12VDC @ 1A

DC coaxial
D-Link PoE Adapter for non-PoE products.
Apple MacIntosh AirPort PoE, Extreme 48 V DC RX RX TX DC? DC?? TX DC?? DC?? Converted to ??? DC coaxial
Mac Polarity Unknown
HyperLink Many DC Voltages Available RX RX TX DC+ DC+ TX DC- DC- same as input DC coaxial and others available Variety of Options Available to Fit Most Brands of PoE
NYC Wireless
Roll Your Own
12 or 24 or 48 V DC RX RX TX DC+ DC+ TX DC- DC- same as input DC coaxial
or as reqd
New York City Wireless PoE
3Com AirConnect 24 V DC RX RX TX spare spare TX DC+ DC-     3Com AirConnect wireless access points
Alvarion VL 55 Vdc RX RX TX DC+ DC- TX DC+ DC-      
TP-link TL-SF1008P   DC- DC- DC+         DC+      
Polycom IP500 / 501 12V DC RX RX TX DC- DC- TX DC+ DC+     The only difference between regular PoE injectors and the Polycom one is the inverted polarity.

PoE - powered devices should obey following specifications:

Parameter Min Max
Signature Resistance, KOhm 23.75 26.25
Startup Time (till I>10mA), ms   300
Operating Input Voltage Range, V 36 57
Must Turn on Voltage, V 44  
Must Turn off Voltage, V 30 V  
Input Current (@36Vdc), mA 10 350
Input Current, Peak, mA   400

Maximum length of the cable PoE UTP 5cat.

Input Voltage 9 V: < 30 m

Input Voltage 12 V: < 60 m

Input Voltage 24 V and more answers the quality IEEE 802.3af standard.


8 pin RJ45 (8P8C) male connector layout
Разъем 8 pin RJ45 (8P8C) male
На распиновку Power over Ethernet (POE) есть 39 отзыв(а): 35 положительных и 1 отрицательных.

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