ZHCSMU0D July 2009 – December 2020 TPS23753A
The waveforms of Figure 8-3 demonstrate detection, classification, and start-up from a Type 1 PSE. The key waveforms shown are VVDD-VSS, VRTN-VSS, and IPI. IEEE 802.3at requires a minimum of two detection levels; however, four levels are shown in this example. Four levels guard against misdetection of a device when plugged in during the detection sequence.