U.S. patent application number 11/637085 was filed with the patent office on 2007-06-14 for providing detailed information on powered device in system for supplying power over communication link.
This patent application is currently assigned to LINEAR TECHNOLOGY CORPORATION. Invention is credited to Clayton Reynolds Stanford.
Application Number | 20070135086 11/637085 |
Document ID | / |
Family ID | 37719173 |
Filed Date | 2007-06-14 |
United States Patent
Application |
20070135086 |
Kind Code |
A1 |
Stanford; Clayton Reynolds |
June 14, 2007 |
Providing detailed information on powered device in system for
supplying power over communication link
Abstract
A powered device (PD) configured for receiving power over a
communication link, such as an Ethernet link, has a power interface
controller for implementing a power supply protocol. The power
interface controller acquires multiple pieces of PD information
representing multiple characteristics of the PD for transferring
the PD information to a power supply device.
Inventors: |
Stanford; Clayton Reynolds;
(Summerland, CA) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
LINEAR TECHNOLOGY
CORPORATION
|
Family ID: |
37719173 |
Appl. No.: |
11/637085 |
Filed: |
December 12, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60749048 |
Dec 12, 2005 |
|
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|
Current U.S.
Class: |
455/402 ;
340/310.11; 370/402; 379/402; 700/286; 713/310 |
Current CPC
Class: |
H04L 12/10 20130101;
Y04S 40/00 20130101; H04L 25/0264 20130101; Y02D 30/00 20180101;
H04L 49/40 20130101; H04L 41/08 20130101 |
Class at
Publication: |
455/402 ;
700/286; 713/310; 370/402; 379/402; 340/310.11 |
International
Class: |
H04M 9/00 20060101
H04M009/00; G05D 11/00 20060101 G05D011/00; G06F 1/00 20060101
G06F001/00; H04L 12/28 20060101 H04L012/28; G05B 11/01 20060101
G05B011/01 |
Claims
1. A powered device (PD) configured for receiving power over a
communication link, comprising: a power supply interface controller
for implementing a power supply protocol performed to receive power
from a power supply device over the communication link, the power
supply interface controller being configured for acquiring multiple
pieces of PD information representing multiple characteristics of
the PD.
2. The device of claim 1, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information to the power supply device over the
communication link.
3. The device of claim 1, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information to the power supply device during an
initialization procedure performed when the PD is being connected
to the power supply device.
4. The device of claim 1, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information to the power supply device during a
power-on procedure performed before the power supply device
provides power to the PD.
5. The device of claim 1, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information to the power supply device after the power
supply device provides power to the PD.
6. The device of claim 1, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information to the power supply device in a single
data packet containing the multiple pieces of PD information.
7. The device of claim 1, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information in a sequence of data packets, each of
which represents a separate characteristic of the PD.
8. The device of claim 1, wherein the power supply interface
controller is further configured for receiving power from the power
supply device over a physical layer of a communication network
including the communication link, and for transferring the multiple
pieces of PD information over a link layer of the communication
network.
9. The device of claim 8, wherein the power supply interface
controller is further configured for transferring the multiple
pieces of PD information to the power supply device using a Link
Layer Discovery Protocol.
10. The device of claim 1, wherein the power supply interface
controller is further configured for receiving power from an
Ethernet link.
11. The device of claim 1, wherein the power supply interface
controller is further configured for storing the multiple pieces of
PD information.
12. The device of claim 12, wherein the power supply interface is
further configured for updating stored PD information during
operation of the PD.
13. The device of claim 1, wherein the power supply interface
controller is configured for acquiring information on average power
consumption of the PD.
14. The device of claim 1, wherein the power supply interface
controller is configured for acquiring information on peak power
consumption of the PD.
15. The device of claim 1, wherein the power supply interface
controller is configured for acquiring information on duty cycle of
peak power consumption of the PD.
16. The device of claim 1, wherein the power supply interface
controller is configured for acquiring information on a priority of
providing power to the PD.
17. The device of claim 1, wherein the power supply interface
controller is configured for acquiring information on a connection
line for delivery of power to the PD.
18. The device of claim 1, wherein the power supply interface
controller is configured for acquiring information on current
consumption.
19. The device of claim 1, wherein the power supply interface
controller is configured for programming the multiple pieces of PD
information into a PD memory during manufacturing of the PD.
20. A system for powering a PD over a communication link,
comprising: a power supply device coupled to the communication link
for providing power to the PD; the power supply device being
configured for performing a PD initialization procedure to
initialize providing power to the PD; the power supply device being
further configured for receiving during the PD initialization
procedure, multiple pieces of PD information representing multiple
characteristics of the PD.
21. The system of claim 20, wherein the power supply device is
configured for receiving the multiple pieces of PD information
during a classification procedure performed to determine maximum
power level required by the PD.
22. The system of claim 20, wherein the power supply device is
configured for receiving a PD information packet having multiple
fields, each of which represents a characteristic of the PD.
23. The system of claim 20, wherein the power supply device
contains a power management mechanism for managing power allocation
to multiple PDs.
24. The system of claim 23, wherein the power management mechanism
is responsive to the multiple pieces of PD information.
25. The system of claim 24, wherein based on the multiple pieces of
PD information, the power management mechanism determines whether
the PD have an alternative power supply.
26. The system of claim 24, wherein based on the multiple pieces of
PD information, the power management mechanism determines how much
power the PD receives.
27. The system of claim 24, wherein based on the multiple pieces of
PD information, the power management mechanism determines whether
power to the PD should be reduced during a predetermined
condition.
28. The system of claim 24, wherein based on the multiple pieces of
PD information, the power management mechanism determines whether
the PD be powered during a predetermined condition.
29. The system of claim 20, wherein the power supply device is
configured for supplying power to the PD over an Ethernet link.
30. The system of claim 20, wherein the power supply device is
configured for providing power to the PD over a physical layer of a
communication network including the communication link, and for
receiving the multiple pieces of PD information over a link layer
of the communication network above the physical layer.
31. The system of claim 30, wherein the power supply device is
configured for receiving the multiple pieces of PD information
using a Link Layer Discovery Protocol.
32. The system of claim 20, wherein the power supply device is
configured for providing power to the PD and receiving the multiple
pieces of PD information over a physical layer of a communication
network
33. The system of claim 20, wherein the power supply device is
configured for receiving information on a minimum power level
needed by the PD to perform predefined tasks required to prevent
the PD from being damaged.
34. The system of claim 20, wherein the power supply device is
configured for receiving information from the PD as to whether
operation of the PD is critical for an emergency condition.
35. The system of claim 20, wherein the power supply device is
configured for receiving from the PD a table of power consumption
levels to estimate power consumption of the PD for a predetermined
time period.
36. The system of claim 20, wherein the power supply device is
configured for receiving information on physical layer connection
of the PD to determine how much power is being lost due to the
physical layer connection.
37. The system of claim 20, wherein the power supply device is
configured for receiving information from the PD on-the-fly.
38. A local area network comprising: at least a pair of network
nodes, a network hub, and communication cabling for connecting the
network nodes to the network hub to provide data communications,
the network hub having a power supply device for providing power to
a PD over the communication cabling, at least one network node
being configured to store multiple pieces of PD information
representing multiple characteristics of the PD.
39. The network of claim 38, wherein the network node is configured
for transferring the multiple pieces of PD information to the power
supply device when the PD is being connected to the power supply
device.
40. The network of claim 38, the power supply device configured for
receiving a PD information packet representing the multiple pieces
of PD information.
41. The network of claim 38, wherein the power supply device is
configured for supplying power to the PD over a physical layer of
the network, and for receiving the multiple pieces of PD
information over a link layer of the network.
42. The network of claim 38, wherein the power supply device is
configured for supplying power to the PD and for receiving the
multiple pieces of PD information over a physical layer of the
network
43. The network of claim 38, wherein the network hub and the
network nodes are configured in an Ethernet network.
44. A method of power management of multiple powered devices
provided with power over a data communication network, the method
comprising the steps of: obtaining over the data communication
network, multiple pieces of information representing multiple
characteristics of the powered devices, and based on the obtained
information, allocating power provided over the data communication
network to the powered devices.
Description
[0001] This application claims priority of and incorporates by
reference provisional U.S. patent application No. 60/749,048 filed
on Dec. 12, 2005, and entitled "SYSTEM AND METHOD FOR SUPPORTING
ADVANCED POWER OVER ETHERNET SYSTEM."
TECHNICAL FIELD
[0002] This disclosure relates to power supply systems, and more
particularly, to circuitry and methodology for providing
information relating to a powered device coupled to a communication
link, such as an Ethernet link.
BACKGROUND ART
[0003] Over the years, Ethernet has become the most commonly used
method for local area networking. The IEEE 802.3 group, the
originator of the Ethernet standard, has developed an extension to
the standard, known as IEEE 802.3af, that defines supplying power
over Ethernet cabling. The IEEE 802.3af standard defines a Power
over Ethernet (PoE) system that involves delivering power over
unshielded twisted-pair wiring from a Power Sourcing Equipment
(PSE) to a Powered Device (PD) located at opposite sides of a link.
Traditionally, network devices such as IP phones, wireless LAN
access points, personal computers and Web cameras have required two
connections: one to a LAN and another to a power supply system. The
PoE system eliminates the need for additional outlets and wiring to
supply power to network devices. Instead, power is supplied over
Ethernet cabling used for data transmission.
[0004] As defined in the IEEE 802.3af standard, PSE and PD are
non-data entities allowing network devices to supply and draw power
using the same generic cabling as is used for data transmission. A
PSE is the equipment electrically specified at the point of the
physical connection to the cabling, that provides the power to a
link. A PSE is typically associated with an Ethernet switch,
router, hub or other network switching equipment or midspan
device.
[0005] PD is a device that is either drawing power or requesting
power. Among examples of PDs are such devices as digital IP
telephones, wireless network access points, PDA or notebook
computer docking stations, cell phone chargers, HVAC thermostats,
factory automation equipment, ID scanners, security systems, credit
card terminals, and keyless entry systems.
[0006] PSE searches the link for a PD requesting power, optionally
classifies the PD, supplies power to the link if a PD is detected,
monitors the power on the link, and disconnects power when it is no
longer requested or required. PD participates in the PD detection
procedure by presenting a PoE detection signature defined by the
IEEE 802.3af standard. If the detection signature is valid, the PD
has an option of presenting a classification signature to the PSE
to indicate how much power it will draw when powered up. Based on
the determined class of the PD, the PSE applies the required power
to the PD.
[0007] Power supply cost in a PoE system can be significant. In
order to better utilize the power supply, a power management system
may be utilized to oversee the distribution of power between
multiple PDs. There are two conflicting requirements associated
with the power supply that must be addressed by a power management
system. In order to save power supply cost, it is desirable to use
the smallest power supply possible, which inherently means that the
power supply will be operated near its maximum output power.
Conversely, in order to avoid running out of power, it is desirable
to reserve the worst-case maximum power consumption for each PD
connected to the system so that all PDs can operate at maximum
power level simultaneously without the power supply becoming
overloaded.
[0008] If all PDs have constant power consumption, then these two
requirements can be met simultaneously. However, if the system
contains PDs that normally run at a low power level but have
transient high power usage, this causes a conflict between the two
requirements. For example, if the power supply is sized to run near
it's maximum capacity and multiple PDs consume maximum power, the
system may be overloaded. If the power supply is sized to handle
the maximum load of all PDs simultaneously, then the majority of
the time the power supply will be running well below it's rated
output.
[0009] Currently, information on a PD provided to the power
management system is limited to the PD class representing the
maximum power level of the PD. This information is communicated to
the PSE during the classification operation. In addition, after the
PD is powered up and running, the PSE is able to measure the actual
PD current.
[0010] Based on the PD classification information, the power
management system can allocate the maximum power consumption for
each PD. The power management system can also look at the measured
PD current representing the real-time PD power consumption and add
PDs to the PoE system until the real-time power consumption hits
some predetermined level.
[0011] However, PD information currently provided to the PSE is not
sufficient for the power management system to make intelligent
decisions about the power consumption characteristics of the
connected PDs and perform the riskibenefit analysis of powering
more PDs on a PoE system. Therefore, there is a need for a system
that would provide the power management system with more detailed
information on PDs.
SUMMARY OF THE DISCLOSURE
[0012] In accordance with one aspect of the present disclosure, a
powered device (PD) configured for receiving power over a
communication link, such as an Ethernet link, has a power interface
controller for implementing a power supply protocol. The power
interface controller is configured for acquiring multiple pieces of
PD information representing multiple characteristics of the PD for
transferring the information to a power supply device. For example,
the multiple pieces of PD information may be programmed into the PD
during assembly or acquired by the PD while it is operating.
[0013] The various PD characteristics may be transmitted to the
power supply device over the communication link during an
initialization procedure when the PD is first connected to the
power supply device. For example, the PD information may be
transferred during or after classification. Alternatively, the PD
information may be provided to the power supply device during or
after PD power-on.
[0014] The multiple pieces of PD information may be transferred to
the power supply device in a single data packet or in a sequence of
data packets, each of which represents a separate characteristic of
the PD.
[0015] While power from the power supply device is received over a
physical layer of the communication network, the multiple pieces of
PD information may be transferred over a link layer of this network
above the physical layer. For example, a Link Layer Discovery
Protocol may be used for PD information transfer.
[0016] Among the multiple pieces of PD information acquired, there
may be information on the average power consumption of the PD, peak
power consumption, duty cycle of peak power consumption, priority
of providing power to the PD, information on a connection line used
for delivery of power to the PD, etc. Alternatively, current
consumption information may be acquired instead of power
consumption information.
[0017] In accordance with another aspect of the disclosure, a power
supply device coupled to a communication link, such as an Ethernet
link, may be configured for receiving multiple pieces of PD
information representing multiple characteristics of the PD during
a PD initialization procedure.
[0018] In accordance with a further aspect of the disclosure, a
local area network having at least a pair of network nodes, a
network hub, and communication cabling for connecting the network
nodes to the network hub to provide data communications, may
include a power supply device arranged in the network hub for
providing power to a PD over the communication cabling. At least
one network node may be configured to store multiple pieces of PD
information representing multiple characteristics of the PD.
[0019] In accordance with a method of the present disclosure the
following steps are carried out to perform power management of
multiple powered devices provided with power over a data
communication network: [0020] obtaining over the data communication
network, multiple pieces of information representing multiple
characteristics of the powered devices, and [0021] based on the
obtained information, allocating power to the powered devices.
[0022] Additional advantages and aspects of the disclosure will
become readily apparent to those skilled in the art from the
following detailed description, wherein embodiments of the present
disclosure are shown and described, simply by way of illustration
of the best mode contemplated for practicing the present
disclosure. As will be described, the disclosure is capable of
other and different embodiments, and its several details are
susceptible of modification in various obvious respects, all
without departing from the spirit of the disclosure. Accordingly,
the drawings and description are to be regarded as illustrative in
nature, and not as limitative.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The following detailed description of the embodiments of the
present disclosure can best be understood when read in conjunction
with the following drawings, in which the features are not
necessarily drawn to scale but rather are drawn as to best
illustrate the pertinent features, wherein:
[0024] FIG. 1 is a diagram illustrating a PoE system of the present
disclosure.
[0025] FIG. 2 is a diagram illustrating a PD characterization
mechanism of the present disclosure that captures information about
PD and transmits the PD information to a power supply
mechanism.
DETAILED DISCLOSURE OF THE EMBODIMENTS
[0026] The present disclosure will be made using the example of
providing PD information to a PSE in a PoE system. It will become
apparent, however, that the concepts described herein are
applicable to any system for providing power over a communication
link.
[0027] For example, a system of the present disclosure may be used
in a local area network (LAN) having a plurality of nodes, a
network hub and communication cabling connecting the nodes to the
network hub for providing data communications. The network hub may
have a power supply device for providing power to a PD over the
communication cabling. The LAN may include a system for providing
detailed PD information to the power supply device.
[0028] FIG. 1 shows a simplified block-diagram illustrating a PoE
system 10 including a PSE 12 having multiple ports 1 to 4
connectable to Powered Devices (PD1 to PD4) via respective links,
each of which may be provided using 2 or 4 sets of twisted pairs
within an Ethernet cable. Although FIG. 1 shows four ports of the
PSE 12, one skilled in the art would realize that any number of
ports may be provided to support power supply to the respective
number of PDs.
[0029] The PSE 12 may interact with each PD in accordance with the
IEEE 802.3af standard. In particular, the PSE 12 and the PD
participate in the PD detection procedure, during which the PSE 12
probes a link to detect the PD. If the PD is detected, the PSE 12
checks the PD detection signature to determine whether it is valid
or non-valid. The valid and non-valid detection signatures are
defined in the IEEE 802.3af standard. While the valid PD detection
signature indicates that the PD is in a state where it will accept
power, the non-valid PD detection signature indicates that the PD
is in a state where it will not accept power.
[0030] If the signature is valid, the PD has an option of
presenting a classification signature to the PSE to indicate the
maximum power the PD will draw when powered up. For example, a PD
may be classified as class 0 to class 4. A PD of class 1 requires
that the PSE supplies at least 4.0W, a PD of class 2 requires that
the PSE supplies at least 7.0W, and a PD of class 0, 3 or 4
requires at least 15.4W. Based on the determined class of the PD,
the PSE 12 may allocate the maximum power required by the PD and
provide this power to the PD.
[0031] In a conventional PoE system, the PD class is the only
information acquired by the power supply interface when the
respective PD is being set up for receiving power over an Ethernet
link. For example, in response to a probing voltage from the PSE
12, the PD power supply interface may draw classification current
representing a desired class of the PD. For class 0 , the PD power
supply interface may draw current in the range from 0 mA to 4 mA;
for class 1, the classification current may be from 9 mA to 12 mA;
for class 2--from 17 mA to 20 mA; for class 3--from 26 mA to 30 mA;
and for class 4, the PD power supply interface may draw current
from 36 mA to 44 mA. The PD power supply interface may include a
classification resistor RCLASS having a value selectable to set a
desired magnitude of the classification current.
[0032] Based on the PD classification information, the PSE 12 can
allocate the maximum power required for each PD. However, this
information is not sufficient to allow the PSE 12 to make
intelligent decisions about the power consumption characteristics
of PDs being powered up and perform the risk/benefit analysis of
powering more PDs.
[0033] FIG. 2 illustrates a PD characterization mechanism 100 of
the present disclosure that enables the PSE 12 to obtain PD
parameter information representing multiple parameters of the PD.
The PD characterization mechanism 100 employs a PSE system
controller 110 that controls interface circuits of PSE ports 1, 2,
3, . . . , N to supply power from a power supply 112 to PDs 1, 2,
3, . . . , N linked to the respective ports. In particular, the PSE
system controller 110 may run a power management routine 114 to
control allocation of power to each of the PDs in the PoE system
based on power supply capacity information from the power supply
112.
[0034] For example, the PDs may be such devices as digital IP
telephones, wireless network access points, PDA or notebook
computer docking stations, cell phone chargers, HVAC thermostats,
factory automation equipment, ID scanners, security systems, credit
card terminals, keyless entry systems, etc. The power management
routine 114 may have access to a PD information table 116
containing detailed information on PDs 1, 2, 3, . . . N that may be
powered by the PSE. For example, the PD information table 116 may
have a separate section for each PD connectable to the PSE. The PD
information table 116 may be stored in a memory device arranged in
the PSE or outside of the PSE. As discussed in more detail below,
the detailed PD information enables the power management routine
114 to make intelligent power management decisions so as to supply
power to the maximum possible number of PDs using limited power
supply capability.
[0035] Each of the PDs 1, 2, 3, . . . ,N may include a respective
PD system controller 202-1, 202-2, 202-3, . . . , 202-N that
controls power to the PD over the Ethernet link, and a respective
PD interface circuit 204-1, 204-2, 204-3, . . . , 204-N linked to
the corresponding PSE port to support interaction between the PD
and the PSE. Each of the PD system controllers 202-1, 202-2, 202-3,
. . . , 202-N has access to a respective PD information table
206-1, 206-2, 206-3, . . . , 206-N containing multiple values
characterizing various aspects of the PD. For example, the PD
information table 206 may include values representing such
characteristics of the PD as the average power consumption, peak
power consumption, duty cycle of peak power consumption, power
priority level, etc. The PD information table 206 may be stored in
a memory device arranged in the respective PD or outside of the
PD.
[0036] When a PD is built or configured for receiving power over
the Ethernet, the PD system controller 202 may acquire multiple
pieces of PD information that could be helpful to enable the PSE to
provide efficient power management. In particular, the PD system
controller 202 may obtain values representing multiple PD
characteristics relevant for power management. The PD system
controller 202 may load these values into the PD information table
206 and may update them if necessary. The PD system controller 202
may be programmed to acquire values of PD characteristics
automatically, for example, during PD set up or testing.
Alternatively, the PD information may be entered manually by a user
or a designer and then programmed into the memory during
manufacturing. In addition, the PD system controller 202 may place
into the PD information table 206 various information relating to
operating PD conditions or conditions of the connection lines.
[0037] During an initialization procedure that may be performed
each time a particular PD is being connected to the PSE, the PD
system controller 202 reads the PD information table 206 to
transfer all or selected PD information to the PSE system
controller 110 that places the information into the respective
section of the PD information table 116. Alternatively, the PD
system controller 202 may transfer the stored information to the
PSE system controller 110 during a PD classification procedure,
after the classification procedure, during the PD power on sequence
or when the PD is up and running. The PD information stored in the
PD information table 116 of the PSE may be updated during the PD
operation, if necessary. Some PD information may be monitored by
the PSE controller 110 or the PD controller 202 and may be provided
directly to the power management routine 114 "on-the-fly" without
storing it in the information table 206 of the PD and/or in the
information table of the PSE.
[0038] Multiple pieces of PD information representing multiple
characteristics of a PD may be sent from the PD to the PSE in one
information package transmitted during the initialization procedure
or at any other desired period of time. Alternatively, the detailed
PD information may be sent in a sequence of information packages,
each of which may be sent at a desired time period and may
represent information on one or more characteristics of the PD.
[0039] A data exchange protocol may be established between the PSE
and the respective PD to support transferring the detailed PD
information from the PD to the PSE. For example, a two-way
communication may be provided between the PSE interface port and
the interface circuit of the respective PD. While power from the
PSE to PDs is provided over the physical layer of the Ethernet
network linking the PSE and the PDs, a transfer of the detailed PD
information may be carried out over the link layer of the Ethernet
network above the physical layer. For example, Link Layer Discovery
Protocol (LLDP) ratified as IEEE standard 802.1AB-2005 may be
employed to support the PD characterization mechanism 100. LLDP is
a neighbor discovery protocol. It allows Ethernet network devices
to advertise information about themselves to other nodes on the
network and store the information they discover.
[0040] In particular, LLDP may be used to define a set of common
messages for the PSE and PDs. These messages may be transmitted
between the PSE and PDs in accordance with LLDP. In particular,
LLDP messages may convey detailed PD information from the PD to the
PSE. Multiple LLDP messages corresponding to respective
characteristics of the PD may be transmitted in one LAN packet in
the form of a type length value (TLV) field. Alternatively, the PD
parameters may be transferred in a sequence of data packets, each
of which represents a respective PD characteristic. As defined by
the LLDP, the received messages may be stored in Management
Information Base (MIB) arranged in accordance with IEEE-defined
Simple Network Management Protocol (SNMP).
[0041] Alternatively, the transfer of detailed PD information from
the PD to the PSE may be provided over the physical layer. For
example, parameters of signals involved in the PoE protocol may be
modulated to transmit required information from the PD to the PSE.
Examples of data communication between the PSE and the PD are
described in copending patent application Ser. No. 11/273,255 filed
on Nov. 15, 2005, entitled "PROVIDING DATA COMMUNICATION BETWEEN
POWER SUPPLY DEVICE AND POWERED DEVICE IN SYSTEM FOR SUPPLYING
POWER OVER COMMUNICATION LINK" and assigned to Linear Technology
Corporation, the assignee of the present application.
[0042] As indicated above, the PSE may utilize the detailed PD
information provided by multiple PDs to make the power management
routine 114 more efficient. In particular, a PD may acquire and
send information on its average power consumption. This information
allows the power management routine 114 to allocate to PDs power
levels corresponding to their average power consumption instead of
their maximum power consumption.
[0043] The information on the peak power consumption, together with
information on the duty cycle of the peak power consumption,
enables the power management routine 114 to determine probability
that multiple PDs will require peak power at the same time. Knowing
this probability, the power management routine 114 may estimate
total power required for a certain time period. Moreover, the PSE
power supply 112 may be able to operate in an overload mode for a
certain duration of time. The calculated probability of multiple
PDs operating at their peak power consumption allows the PSE to
determine whether the PSE power supply 112 will be able to operate
in the overload mode long enough to support multiple PDs during
periods of peak power consumption.
[0044] PDs may transfer information on their priorities to support
a PD priority scheme of the power management routine 114. As the
power available from the power supply 112 becomes restricted, the
PSE system controller 110 may remove or reduce power allocated to a
lower-priority PD in order to grant a request for power from a
higher-priority PD. Also, the priority scheme enables the PSE to
reduce or remove power allocated to a lower-priority PD before
reducing or removing power allocated to a higher-priority PD.
[0045] PDs may transfer information on a minimum power level needed
to perform some predefined tasks required to prevent that PD from
being damaged. For example, the PD may indicate the power level
required to keep its memory alive and support minimum functions. In
response to this request, the power management routine 114 may
prevent the power allocated to that PD from being reduced below the
requested minimum level.
[0046] PDs may transfer tables indicating their power consumption
for particular operational functions to allow the power management
routine 114 to allocate sufficient power for mandatory operations.
PD may provide an indication whether its operation is critical for
certain emergency conditions such as fire, power loss, etc. and
whether the PD has a backup or an alternative power supply
available.
[0047] PDs may provide the PSE with tables of power consumption
levels, associated time durations, and duty cycles for each of the
defined power levels. Based on these table, the power management
routine 114 may estimate total power consumption for various time
periods.
[0048] Currently, the PSE must allocate power to compensate for the
maximum possible power drop due to the cable on the PD side. To
enable the power management routine 114 to reduce power allocated
to the cable drop, PD may provide the PSE with information relating
to the PD physical layer connection. For example, the PD may
indicate the voltage at its port, the resistance of its cable, its
wiring information such as the use of Ethernet data pairs, spare
pairs or both pairs. This information enables the PSE to determine
how much power is being actually dropped in the cable, and to
allocate power to compensate for the actual power drop instead of
the maximum possible power drop.
[0049] Hence, the PD characterization mechanism of the present
disclosure allows the PD to acquire multiple pieces of information
relating to its parameters and conditions. This information is
transferred to the PSE to enable the power management system to
manage power allocation to multiple PDs in a more efficient manner.
For example, the power management system may be able to determine
which PDs have an alternative power supply, how much power each PD
receives, which PDs to drop off in case of overload, and which PDs
to keep powered under various conditions such as emergencies.
[0050] A two way communication may be provided between the PSE and
PD to enable the PSE to send power management commands to PD. For
example, the PSE may request particular PDs to limit their power
consumption to predefined levels in order to keep the maximum
number of PDs operating, even if some of them operate with reduced
functionality.
[0051] The foregoing description illustrates and describes aspects
of the present invention. Additionally, the disclosure shows and
describes only preferred embodiments, but as aforementioned, it is
to be understood that the invention is capable of use in various
other combinations, modifications, and environments and is capable
of changes or modifications within the scope of the inventive
concept as expressed herein, commensurate with the above teachings,
and/or the skill or knowledge of the relevant art.
[0052] For example, one skilled in the art would understand that
instead of PD power consumption information, PD current consumption
information may be acquired by a PD controller and transferred to a
PSE. Further, detailed information on characteristics of a
particular PD may be acquired by an external controller remote with
respect to the PD. For example, the external controller may be
provided at a node of a local area network, or at a network hub,
together with the PSE.
[0053] The embodiments described hereinabove are further intended
to explain best modes known of practicing the invention and to
enable others skilled in the art to utilize the invention in such,
or other, embodiments and with the various modifications required
by the particular applications or uses of the invention.
[0054] Accordingly, the description is not intended to limit the
invention to the form disclosed herein. Also, it is intended that
the appended claims be construed to include alternative
embodiments.
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