IEEE P802.3CV:2020 pdf free download – Draft Standard for EthernetAmendment: Maintenance #15: Power over Ethernet
Power entities that implement Data Link Layer classification shall support the Power via MDI TLV DLLclassification extension fields shown in Figure 79-3 after the Pl has been powered.Type 3 or Type 4 powerentities that implement Data Link Layer classification and are connected to another Type 3 or Type 4 powerentity shall support the Type 3 and Type 4 extension fields shown in Figure 79-3 after the Pl has beenpowered.Such entities, when connected to a Type 1 or Type 2 power entity, may support the Type 3 andType 4 extension fields shown in Figure 79-3 after the Pl has been powered. Type 1 and Type 2 devicesshall not include the Type 3 and Type 4 extension fields in the transmitted Power via MDITLV.
Note: some implementations of the Power via MDI TLV in Type 1 and Type 2 power entities ignore TLVs that havegreater than 12 octets. In order to be interoperable with these implementations, Type 3 and Type 4 power entities are per-mitted to transmit 12 octet TLVs (without the Type 3 and Type 4 extension) after first transmitting at least one valid 29octet TLV(including Type 3 and Type 4 extension). Table 79-1a lists the recommended Power via MDITLV formats forcach combination of power entity Types.
After power up, a PD that implements Autoclass shall draw its highest required power,PAutoclss pp, subjectto the requirements on PClass pp in 145.,3.8.4，throughout the period bounded by TAUTo ppl andTAuTo PD2, measured from when Vpp rises above Von pp. The PD is restricted to a maximum power drawof PAutoclass pp until the PD successfully negotiates a higher power level through Data Link Layerclassification as defined in 145.5.A PD that draws less than PClass pp max for Class l during the periodbounded by TAuTo ppj and TAUTo pp2 indicates to the PSE that the power allocation should be determinedby the assigned Class.By doing this the PD can abort the Physical Layer Autoclass procedure.
Change the last paragraph of 145.3.8.1 as follows:
When the PD is in POWEROFF and Vpp falls below VMark_ thy the PD transitions to NOPOWER and mayshow a valid or invalid detection signature, and may or may not draw mark current, draw any class current,and show MPS.Interoperability between PSE and PD is no longer guaranteed when the nopower variable isTRUE or the PD has entered NOPOWER_INRUSH since the last time Vpp was below VResct_PD max.
145.3.8.2 Input average power
Change third paragraph in 145.3.8.2 as follows:
A PD that has enabled Autoclass during Physical Layer classification and drew a power higher than Class 1power during the period bounded by TAUTo pp and TAUTo PD2 or has requested Autoclass through DLL,shall not draw more power than PAutoclass pp, unless the PD successfully negotiates a different power level,up to the PD requested Class, through Data Link Layer classification as defined in 145.5.
For single-signature PDs assigned to Class 8 and for dual-signature PDs assigned to Class 5，whenadditional information is available to the PD regarding actual link section DC resistance between the PSE PIand the PD Pl, in any operating condition with any static voltage at the Pl, the peak power shall not exceedmaximum-PPort pp max for single-signature PDs and maximum-PPort PD-2p max for dual-signature PDs atthe PSE Pl-for more than Tcur min, as defined in Table 145-16 and with 5% duty cycle.