Appendix B
IEEE 802.3af Guard-bands and beyond
The IEEE 802.3af standard defines a lower and upper guard-band around the resistive signature range.
Any PD value in the guard-band range is considered non-compliant. Additionally, PD values beneath or
above the guard-band ranges are considered invalid signatures. Both invalid and non-compliant signatures
mandate removing power almost instantly by the PSE.
Table B – Parameters for an invalid or non-compliant power signature
Parameter
Conditions
Range of Values
Condition
Voltage Ramp-up
V < 10.1V
12K
Ω
< or > 45K
Ω
Invalid
Signature
Input Capacitance
V < 10.1V
> 10 µF
Invalid Signature
Lower Guard-band
Start up and Steady State 12K
Ω
– 23.75K
Ω
Non-Compliant
Upper Guard-band
Start up and Steady State 26.25K
Ω
– 45K
Ω
Non-Compliant
MJK
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2006 Avaya Inc. All Rights Reserved.
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