HK1188883A - Physical layer device auto-adjustment based on power over ethernet magnetic heating - Google Patents

Abstract

Embodiments of the present invention are directed to physical layer device auto-adjustment based on power over Ethernet (PoE) magnetic heating. In one embodiment, information generated by a PoE module that is indicative of the PoE operation over the network cable (e.g., level of current, heating, etc.) is made available to the physical layer device (PHY). This information enables the PHY to infer a change in the level of inductance on the line. In response, the PHY can then adjust a characteristic of transmission by the PHY.

Description

Automatic adjustment of physical layer device based on heating and power supply of Ethernet magnetic element

This application claims priority from united states provisional patent application No. 61/658,996 filed on day 6/13 2012 and united states patent application No. 13/535,469 filed on day 6/28 2012.

Technical Field

The present invention relates generally to network power systems and methods, and more particularly to physical layer device autotuning based on power over ethernet magnetics heating.

Background

Power over ethernet (PoE) provides a framework for transferring power from a Power Sourcing Equipment (PSE) to a Powered Device (PD) over an ethernet cable. There are a variety of PDs including voice over IP (VoIP) phones, wireless LAN access points, bluetooth access points, webcams, computing devices, etc.

In PoE applications such as described in IEEE802.3af (now part of IEEE802.3 version and its modifications) and 802.3at specifications, a PSE may transfer power to a PD over multiple wire pairs. According to ieee802.3af, the PSE may transfer up to 15.4W of power over two pairs to a single PD. On the other hand, according to ieee802.3at, the PSE can transfer up to 30W of power to a single PD over two pairs. Other proprietary solutions may potentially deliver higher or different levels of power to the PD. The PSE may also be configured to transfer power to the PD using four wire pairs.

Disclosure of Invention

According to an aspect of the invention, there is provided a method comprising: receiving, in a physical layer device, information generated by a power over ethernet module, the information representing a current level transmitted over a plurality of twisted wire pairs coupled to the physical layer device via a corresponding plurality of data converters, the power over ethernet module coupled to a center tap of the plurality of data converters; and adjusting, by the physical layer device, a transmission characteristic in response to the information generated by the power over ethernet module.

Preferably, the method further comprises determining a change in inductance of the data converter based on the information generated by the power over ethernet module. Wherein the determining comprises: based on the current level, a heating level of the data converter is determined.

Preferably, the adjusting comprises: adjusting a transmission voltage envelope of the physical layer device.

Preferably, the adjusting comprises: adjusting a transmission current envelope of the physical layer device.

Preferably, the adjusting comprises: adjusting a waveform output by the physical layer device.

According to yet another aspect of the invention, there is provided a method comprising: receiving, in a physical layer device, information indicative of a heating level of a data converter coupling the physical layer device to a twisted wire pair, wherein a center tap of the data converter is coupled to a power over ethernet module that facilitates transmitting power over the twisted wire pair; and adjusting, by the physical layer device, a transmission characteristic in response to the information indicative of the level of heating of the data converter.

Preferably, the method further comprises: based on said information indicative of the heating level of the data converter, a change in inductance of the data converter is determined.

Preferably, said information indicative of the heating level of the data converter is a temperature sensor reading.

Preferably, said information indicative of the heating level of the data converter is the current level through said data converter.

Preferably, the adjusting comprises: adjusting a transmission voltage envelope of the physical layer device.

Preferably, the adjusting comprises: adjusting a transmission current envelope of the physical layer device.

Preferably, the adjusting comprises: adjusting a waveform output by the physical layer device.

Preferably, the power over ethernet module is a power supply device that transmits power over the twisted wire pair.

Preferably, the power over ethernet module is a powered device that receives power over the twisted wire pair.

According to still another aspect of the present invention, there is provided a physical layer apparatus including: an interface to cause the physical layer device to receive information indicative of an operating condition of a data converter coupling the physical layer device to a twisted wire pair, wherein a center tap of the data converter is coupled to a power over ethernet module that facilitates transmission of power over the twisted wire pair; and a controller to adjust, by the physical layer device, a transmission characteristic in response to the information indicative of an operating condition of the data converter.

Preferably, the controller adjusts a transmission voltage envelope of the physical layer device.

Preferably, the controller adjusts a transmission current envelope of the physical layer device.

Preferably, the controller adjusts a waveform output through the physical layer device.

Drawings

In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings. In the drawings:

fig. 1 illustrates an exemplary embodiment of a power over ethernet system transmitting power over a wire pair used by a data transmission system.

FIG. 2 illustrates an exemplary embodiment of a control mechanism in a physical layer device that is responsive to information reflective of the operating conditions of the magnetic element.

Fig. 3 illustrates an exemplary embodiment of communication operation information between a power over ethernet module and a data transmission system.

FIG. 4 shows a flowchart of an exemplary process according to the present invention.

Detailed Description

The following describes in detail various embodiments of the present invention. While specific embodiments are discussed, it should be understood that this is for exemplary purposes only. One of ordinary skill in the art will recognize that other components and configurations may be used without departing from the spirit and scope of the present invention.

Data communication over ethernet connections assumes a certain and minimum inductance on the line. At higher frequencies, such as those supported by 10GBASE-T, the inductance of the data converter is much lower to allow for a manufacturable magnetic element. In power over ethernet (PoE) applications, a current imbalance may occur in the data converter, which may result in a bias current being present on the data converter in the PoE current path. As the current applied to the network cable increases due to higher power PoE applications, a corresponding decrease in the inductance of the data converter results. These reductions can result in increased Bit Error Rates (BER) for data transmission systems that are sensitive to the level of inductance on the line.

In one embodiment of the invention, information generated by the PoE module (e.g., current level, heat generation, etc.) indicative of PoE operation over the network cable is made available to the physical layer device (PHY). This information will enable the PHY to infer changes in the inductance level on the wire. In response, the PHY may then adjust the transmission characteristics of the PHY. In various embodiments, the PHY may adjust a transmit voltage envelope, a transmit current envelope, a transmit waveform, echo cancellation, and the like.

PoE may be used to transmit power over a pair of wires for data transmission. PoE may be applied in a variety of situations and may be used with data transmission standards such as 10BASE-T, 100BASE-TX, 1000BASE-T, 10GBASE-T, 40GBASE-T or higher data rate transmission systems. In addition to isolation, the data converter used can also be characterized by open circuit inductance (OCL).

In the 100BASE-TX specification, the minimum inductance measured at the transmit pin should be greater than or equal to 350 μ H and a DC bias current of between 0-8mA is injected. Generally, the 100BASE-TX specification of minimum inductance of the data converter on the transmit side is designed to exhibit sufficient inductance that will overcome the killer pattern causing baseline wander to enable the receiver to recover. This specified minimum inductance level ensures compatibility with PHY receivers that expect to see effective inductance on the channel, so that the signal quality and BER of the link are not affected.

Because the inductance requirements are implementation-oriented, the newer 1000BASE-T, 10GBASE-T, 40GBASE-T specifications can identify transmitter sag test requirements. The droop test requirement is a signal characteristic requirement and is related to the OCL of the data converter. With the aid of droop test requirements, newer PHY implementations (e.g., 1000BASE-T, 10GBASE-T, 40GBASE-T, etc.) have been allowed to use lower inductance data converters that can meet the specified signal characteristics.

In the present invention, it is recognized that the lower inductance data converters used in newer PHYs may vary significantly depending on the operating conditions (e.g., temperature, bias current, etc.) of the data converter when used to support PoE applications. This is especially true when considering higher power PoE applications capable of supporting the delivery of near 1A power through a data converter. When such high levels of power are transmitted over the pairs used for data transmission, the corresponding change in inductance of the data converter can greatly affect data transmission system performance.

Before describing the details of the present invention, reference is first made to fig. 1, which fig. 1 shows an exemplary embodiment of a PoE system that transmits power over two wire pairs used by a data transmission system. As shown, the PoE system includes a PSE110 that transfers power to a PD120 over two wire pairs that are also used for data transmission. As will be appreciated, PY specifications such as 1000BASE-T and 10GBASE-T are configured to use four wire pairs. Further, some PoE systems may be configured to transmit power over four wire pairs. For purposes of illustration, only two wire pairs are shown in FIG. 1 for simplicity.

Power transfer by the PSE110 to the PD120 is provided by applying a voltage across the center taps of the data converter 112 and the data converter 114, where the data converter 112 is coupled to the Transmit (TX) wire pairs in the Ethernet cable and the data converter 114 is coupled to the Receive (RX) wire pairs. At the other end of the network link, PD120 receives power through a center tap of data converter 131 and data converter 134.

In general, the PD120 may include a PoE module 142 containing electronics that will cause the PD120 to communicate with the PSE110 in accordance with ieee802.3af, 802.3at, conventional PoE transmissions, or any other type of PoE transmissions. The PD120 also includes a controller 144 (e.g., a pulse width modulation DC: DC controller) that controls a power transistor 146 (e.g., a Field Effect Transistor (FET)), the power transistor 146 providing constant power to a load 150.

Based on ieee802.3at, data communications between PHY110 and PHY130 are typically designed to operate with increasingly more affected data converters and/or signal specifications that do not have to account for high level power. Specifically, an increase in DC current imbalance in the data converter due to transmission of high-level DC power through the network cable with a load current that can reach 1A is not considered. Generally, as the DC bias current through the data converter increases, the OCL of the data converter will decrease. Additionally, as the temperature of the data converter increases for a given DC bias current, the OCL of the data converter will decrease. Thus, the OCL of the data converter can be significantly reduced by the effect of the increased DC bias current and increased temperature that can result from applying PoE to the network cable. Since PHY assumes a certain and minimum inductance on the line, a reduction in OCL of the data converter may result in an increase in BER in the data transmission system.

In the present invention, it is recognized that the data converter may represent a fixed part of the data transmission system on the printed circuit board. Thus, the present invention is characterized in that by adjusting the transmission operation of the PHY, variations in the OCL of the data converter due to PoE applied to the relevant pair of wires in the network cable can be compensated for. In one embodiment, the transmission operation of the PHY may be adjusted by modifying the drive strength of the PHY to compensate for changes in the OCL of the data converter. In various examples, the adjustment of drive strength may be characterized by an adjustment of a transmission voltage envelope, a transmission current envelope, an output waveform, and/or the like. It should be understood that the particular mechanism to adjust the drive strength of the PHY will be implementation dependent. Here, the adjustment of the drive strength can be achieved in such a way that known or inferred variations of the inductance on the wire can be best accounted for. The conditioning process may also depend on the particular mode of operation in which the PHY is operating (e.g., 10BASE-T, 100BASE-TX, 1000BASE-T, 10GBASE-T, 40GBASE-T, etc.). In another embodiment, the transmission operation of the PHY may be adjusted by modifying the echo cancellation process.

The adjustment of the transmission operation of the PHY is based on information reflecting the operating conditions of the data converter magnetic elements. Fig. 2 illustrates an example embodiment of a control mechanism in a PHY that responds to such information. As shown, the PHY210 is coupled to the magnetic element 220 via a Media Dependent Interface (MDI). The magnetic element 220 is coupled to an RJ-45 connector 230, the RJ-45 connector 230 facilitating coupling of the PHY210 to a twisted pair (twisted pair) ethernet cable transmission medium.

As further shown in fig. 2, PHY210 includes a transceiver (TX/RX) 212 that transmits and receives data via the MDI. The transmission operation of the transceiver 212 is controlled by a controller 214, and the controller 214 is responsive to operational information received via a data interface 216. Generally, the operational information is based on the operating conditions of the magnetic element 220 and is used by the controller 214 in configuring or controlling the transmission operations of the transceiver 212.

In one embodiment, the operational information may include information reflecting the operating conditions of the magnetic element 220. In one example, the measurement information is indicative of the PoE current level through the magnetic element 220. In another example, the measurement information represents temperature information that may be derived from current measurements, temperature information measured using a temperature sensor proximate to the magnetic element 220, and so forth. In another example, the measurement information may represent inductance information of the magnetic element 220 derived or measured from the operating condition information. In general, the measurement information may represent any information that enables the controller 214 to determine the need to modify the transceiver 212 to compensate for changes in the OCL of the magnetic element 220.

In another embodiment, the operational information may include operational control signals generated in response to the operating conditions of the magnetic element 220. Here, the operation control signal may be generated by a system or module external to the PHY210, wherein the operation control signal is provided to the PHY210 via the interface 216. In this embodiment, receipt of the operation control signal via the interface 216 may be used by the controller 214 in configuring or controlling the transmission operation of the transceiver 212.

As will be appreciated, the particular type of operational information provided to the PHY210 may vary. Of significance, the operational information derived from the operating conditions of the magnetic element 220 is used by the PHY210 in configuring or controlling the transmission operation of the transceiver 212 to compensate for inductance changes in the magnetic element 220.

Fig. 3 illustrates an exemplary embodiment of communication operational information between a power over ethernet module and a switch. As shown, the switch may include PHYs 310-n that are each coupled to a Switch (SW) module 320. For clarity of illustration, only a single pair of data converters is shown coupled to each PHY 310-n.

Each PHY310-n is also connected to a host 330. In one embodiment, host 330 and Ethernet switch 320 and PHY310-n are combined on a single chip. In another embodiment, the Ethernet switch 320 and the PHYs 310-n are combined on a single chip separate from the host 330, wherein communication with the host 330 is accomplished via a serial interface. Also shown in fig. 3 is PSE340, which is powered through the center tap of the data converter. As shown, PSE340 is also coupled to host 330. In one embodiment, PSE340 is coupled to host 330 via optical isolator 350 that facilitates isolating the boundary.

In the exemplary embodiment of fig. 3, PSE340 may be configured to monitor operating conditions of the data converter. In one example, PSE340 may monitor the current level transmitted through the center tap of the data converter. In another embodiment, PSE340 may determine the heat generation of the data converter based on current information or by a temperature sensor located near the data converter.

Operational information measured or determined by the PSE340 may be provided to the host 330. In one example, host 330 may forward the operational information of the data converter to the associated PHY310-n coupled to the data converter via a data interface between host 330 and PHY 310-n. Based on this operational information, the PHY may then determine how to adjust the transceiver to compensate for the change in inductance represented by the forwarded operational information. In another example, host 330 may process operational information of the data converter to derive control signals that may be used by the associated PHY. In this example, the control signal may be transmitted over the data interface to the associated PHY and used by the PHY to adjust the transceiver to compensate for the inductance change. As will be appreciated, the particular type of operational information transmitted to the PHY will depend on the mechanism used to monitor the operating conditions of the data converter, the capabilities of any intervening processing modules, and the capabilities of the PHY itself.

Having described exemplary embodiments for transferring data converter operational information to a PHY, reference is now made to the flow diagram of fig. 4, and fig. 4 illustrates an exemplary process in accordance with the present invention. As shown, the process begins at step 402, and at step 402, operational information of the data transducer magnetic element is determined. As described above, the particular mechanism used to determine the operational information may vary depending on the implementation. In the example described above with reference to fig. 3, the PoE subsystem can be designed to measure or determine operational information. The PoE subsystem then transmits the operational information to the host module, which is further configured to determine operational information (e.g., control signals) to be transmitted to the PHY. Regardless of the particular implementation, the operational information is ultimately received by the PHY at step 404.

In response to the received operation information, the PHY then adjusts one or more characteristics of the transmission operation of the PHY at step 406. As will be appreciated, the particular mechanism by which the transmission operation (e.g., change in drive strength, change in echo cancellation, etc.) is modified will be implementation dependent. Importantly, the identification of changes in inductance in the data converter due to changes in bias current, heat generation, etc., can be used by the PHY to adjust for changes in inductance in the communication channel.

Here, it should be noted that the variation may be performed at both ends of the channel based on the determined operation information. In one embodiment, the adjustment process may take into account the type of PHY at the far end of the link. For example, when the PHY is coupled to a remote 100BASE-TXPHY as determined by the auto-navigation process, the local transmission system will know that the remote data converter will have an OCL of 350 μ H. This knowledge of the baseline OCL of the remote PHY is useful in determining adjustments to the changes in the inductance of the communication channel. After certain adjustments have been made to the transmission operation of the PHY, operation of the PHY may then begin at step 408. A lower BER will result because the operation is designed to compensate for changes in the inductance of the data converter due to changes in bias current or heating.

Another embodiment of the invention may provide a machine and/or computer readable storage and/or medium having stored thereon a machine code and/or a computer program having at least one code portion executable by a machine and/or computer to cause the machine and/or computer to perform the steps described herein.

These and other aspects of the present invention will become apparent to those of ordinary skill in the art upon review of the foregoing detailed description. While some of the salient features of the invention have been described above, this invention is capable of other embodiments and of being practiced and carried out in various ways that will be apparent to those of ordinary skill in the art upon reading this disclosure, and thus the foregoing description should not be construed as excluding these other embodiments. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

Claims (10)

1. A method, comprising:

receiving, in a physical layer device, information generated by a power over ethernet module, the information representing a current level transmitted over a plurality of twisted wire pairs coupled to the physical layer device via a corresponding plurality of data converters, the power over ethernet module coupled to a center tap of the plurality of data converters; and

adjusting, by the physical layer device, a transmission characteristic in response to the information generated by the power over Ethernet module.

2. The method of claim 1, further comprising: determining a change in inductance of a data converter based on the information generated by the power over Ethernet module.

3. The method of claim 2, wherein the determining comprises: based on the current level, a heating level of the data converter is determined.

4. The method of claim 1, wherein the adjusting comprises: adjusting a transmission voltage envelope of the physical layer device.

5. A method, comprising:

receiving, in a physical layer device, information indicative of a heating level of a data converter coupling the physical layer device to a twisted wire pair, wherein a center tap of the data converter is coupled to a power over ethernet module that facilitates transmitting power over the twisted wire pair; and

adjusting, by the physical layer device, a transmission characteristic in response to the information indicative of the level of heat generation of the data converter.

6. The method of claim 5, further comprising: based on said information indicative of the heating level of the data converter, a change in inductance of the data converter is determined.

7. The method of claim 5, wherein the information indicative of a heating level of a data converter is a temperature sensor reading.

8. The method of claim 5, wherein the information indicative of a heating level of a data converter is a current level through the data converter.

9. The method of claim 5, wherein the adjusting comprises: adjusting a transmission voltage envelope of the physical layer device.

10. A physical layer device, comprising:

an interface to cause the physical layer device to receive information indicative of an operating condition of a data converter coupling the physical layer device to a twisted wire pair, wherein a center tap of the data converter is coupled to a power over ethernet module that facilitates transmission of power over the twisted wire pair; and

a controller to adjust a transmission characteristic by the physical layer device in response to the information indicative of an operating condition of the data converter.