AS1860 Datasheet, PDF (46/51 Pages) List of Unclassifed Manufacturers – 60W/90W PoE PD Controllers

AS1860
POE POWER-ON SEQUENCE
The power-on sequence for PoE operation is shown in Figure 29. The waveform reflects typical voltages present at the
PD during signature, classification and power-on.
Figure 35 - PoE Power-On Sequence Waveform
1. Voltages V1 and V2 are applied by the PSE to extract a signature value.
2. The PSE takes current/impedance readings during Class/Mark Events to determine the class of the PD. At this time, the PD presents a load
current determined by the resistance connected to the RCLASS pin.
3. After the PSE measures the PD load current, if it is a high-power PSE, it presents a mark voltage (6.9-10V), followed by a second classification
voltage. The PD responds by presenting a load current as determined by the resistor on the RCLASS pin. After the PSE measures the PD load
current the second time and determines that is can deliver the requested power, it moves into the On state by raising the voltage to approximately
42V after which the PD operates over the On Range.
Akros Silicon, Inc.
6399 San Ignacio Avenue, Suite 250, San Jose, CA 95119 USA
408.746.9000  http://www.AkrosSilicon.com
46