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Jack PC Hardware User Manual - Training Department
Version 0506
the Jack-PC will consume only 4-6W maximum. Power may vary if demanding USB
peripheral devices or dual monitors are attached to the device.
Class Usage Minimum Power
Levels Output at
the PSE
Maximum Power
Levels at the
Powered Device
0 Default 15.4W 0.44 to 12.95W
1 Optional 4.0W 0.44 to 3.84W
2 Optional 7.0W 3.84 to 6.49W
3 Optional 15.4W 6.49 to 12.95W
4 Reserved for Future
Use
Treat as Class 0 Reserved for Future
Use: A class 4
signature cannot be
provided by a
compliant powered
device
Table 6.2 - IEEE 802.3af PSE and Powered Device Power Classifications
Therefore for swiches with overall power limitations, Jack-PC would not usually exceed the
rack limitations. If the PSE is not capable of supplying class 0 power to the Jack-PCs it may
still be possible to operate at class 2 (7W maximum) although this setting is marginal and may
cause random PoE power down events.
A practical example:
Lets take a rack with Catalyst 6500 series switches (240 ports):
Chip PC Jack-PC EFI-6900 typically requires 5W during normal use and 6W during full-
screen video player operation.
As a comparison - Cisco IP Phone 7960G requires 7W when the phone is ringing at
maximum volume and requires 5W on or off hook.
This is a significant reduction from the 15.4W maximum power allowed for within IEEE
802.3af for class 0 devices. It can be seen that PSE power requirements can be significantly
reduced by budgeting for the power the device actually requires, rather than simply allocating
the maximum power defined within IEEE 802.3af.
To calculate actual switch power use, we can multiply 7W by the number of ports (240) =
1680W.
