A resistor from CLS to VSS programs the classification current per the IEEE standard. The PD power ranges and corresponding resistor values are listed in Table 1. The power assigned should correspond to the maximum average power drawn by the PD during operation.
High-power PSEs may perform two classification cycles if Class 4 is presented on the first cycle. The TPS23754 device presents the same (resistor programmed) class each cycle per the standard.
|CLASS||POWER AT PD||RESISTOR |
|0||0.44||13||1270||Minimum may be reduced by pulsed loading. Serves as a catch-all default class.|
|4||13||25.5||63.4||Not allowed before IEEE 802.3at. Use to indicate a Type 2 PD (high power) device per IEEE 802.3at.|