WP_EA_Overview8023bt_FINAL-标准资料文件.pdf

ethernet alliance Overview of 802.3bt - Power over Ethernet standard Lennart Yseboodt, Philips Lighting David Abramson, Texas Instruments April 2018 ethernet alliance IEEE 802.3bt at a glance The new Power over Ethernet 802.3bt standard is the third revision to the widely adopted IEEE standard that specifies low voltage power transfer to networked devices. The first IEEE PoE standard, 802.3af (2003), was able to provide 13W to devices. This was increased to 255W by 802.3at (2009). With 802.3bt, the amount of power available for devices increases nearly threefold, to 713W, enabling a myriad of new applications. Publication of 802.3bt is expected in the second half of 2018. The overview below shows the power levels defined by 802.3bt and how these relate to the existing PoE standard. All PoE devices (sources or loads) are interoperable, the only limitation being that a new high power PD (Powered Device) will not get the full power from an older or lower power PSE (Power Sourcing Equipment). The different power levels are defined as ‘Classes’. There are four existing Classes, providing up to 255W to PDs. This is being expanded with four new Classes, taking the power level higher, up to 51W for Type 3 PDs and up to 713W for Type 4 PDs. Type 3 (802.3bt) Type 4 Type 1 (802.3af) Type 2 (802.3at) (802.3bt) PSE Class 1 Class 2 Class 3 Class 4 Class 5 Class 6 Class 7 Class 8 4 W 7 W 15.4 W 30 W 45 W 60 W 75 W 90 W 2-pair only (Type 1 2) always 4-pair power 2-pair or 4-pair power (Type 3 4) Class 1 Class 2 Class 3 C