Powered Device Power Requirement Reporting via Isolation Barrier
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Solution Overview
Problem
In modular PD systems, existing technologies are inadequate for dynamically determining and communicating the varying power requirements of sub-modules, such as radios in access point systems, due to the isolation barrier between the Ethernet line side and primary power supply, and the need to ensure compliance with 802.3af or 802.3at power levels.
Innovation Solution
A powered device with a microcontroller on the Ethernet line side determines module population and power requirements by sending a signal across an isolation barrier and communicating these requirements to an external power source, using a circuit that generates a square wave to identify module resistances and calculates power levels, and an optical link to communicate with the host system controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed classification reporting is used in modular PD systems, then the device complexity is reduced and ease of manufacture is improved, but the adaptability to different power requirements of sub-modules deteriorates
Solution Approach 1:
The patent implements dynamic classification reporting where the powered device determines the actual power requirements of installed sub-modules and reports the appropriate classification level accordingly, rather than using a fixed hard-coded classification. This allows the system to adapt to different module configurations while maintaining manageable device complexity through automated detection and reporting mechanisms.
2Adaptability or versatility
If dynamic classification request based on module population is implemented, then the adaptability to different power requirements is improved, but the device complexity increases due to isolation barrier and signal communication requirements
Solution Approach 1:
The patent uses the Ethernet communication interface as an intermediary to transmit power requirement information across the isolation barrier. The line side controller communicates with the isolated side controller through standardized Ethernet protocols, eliminating the need for complex dedicated signaling circuits while maintaining adaptability to different module configurations.
Solution Approach 2:
The patent leverages the existing Ethernet communication infrastructure to serve multiple functions: data transmission, power negotiation, and power requirement reporting. By using the same communication interface for multiple purposes, the system achieves dynamic classification without adding significant device complexity.
3Adaptability or versatility
If the classification hardware determines module power requirements across an isolation barrier, then the adaptability is improved, but the difficulty of detecting and measuring power requirements increases
Solution Approach 1:
The patent replaces physical electrical connection methods for power requirement detection with electronic communication through the Ethernet interface. Instead of using dedicated measurement circuits across the isolation barrier, the system uses digital communication to exchange power requirement information, significantly reducing the difficulty of detection and measurement.
4Reliability
If the powered device communicates power requirements to the external power source, then the reliability of power delivery is improved, but the loss of time for determination and communication increases
Solution Approach 1:
The patent performs power requirement determination and classification reporting during the initial connection phase, before power delivery begins. By completing the power negotiation and classification communication in advance, the system ensures reliable power matching without causing delays in actual power delivery operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and efficient determination and communication of power requirements, allowing for appropriate power level requests and module configuration to match available power, ensuring compliance with 802.3af or 802.3at standards and optimizing power usage within the 5 ms required for 802.3af systems.
Implementation Method 1
A circuit on the line side is configured to send a first signal across the isolation barrier to the installed module. The circuit is configured to determine a power requirement for the installed module based upon a response to the first signal.
Implementation Method 2
an optical link to communicate with the host system controller
Data Source
AI summary
In one embodiment, a powered device is configured to determine module population and the appropriate power requirements for installed modules. The power requirements can be communicated to the power sourcing equipment for the powered device. Optionally, the powered device can receive data representative of available power from the power sourcing equipment and the powered device is responsive to operate accordingly.