Power Over Coax Detection Circuit for Safe Device Powering
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Solution Overview
Problem
Power over Coaxial (PoC) systems face challenges in determining the type of powered device and managing power supply to prevent damage, especially when devices are not powered up or are powered by external sources, and in accurately detecting load disconnection.
Innovation Solution
The power sourcing equipment includes a device detection circuit to identify the type of powered device based on electrical parameters and a load detection circuit to determine load disconnection using different criteria depending on whether the device is powered by the PoC system or an external source, ensuring safe and accurate power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power sourcing equipment transmits power signal to the powered device via coaxial cable, then the powered device can be powered on, but the powered device may be damaged if it is already powered by an external power supply
Solution Approach 1:
The system performs preliminary detection of the powered device type and power state before transmitting power signal. The detection circuit checks whether the powered device is already powered by external power supply or is a non-PoC device, and only transmits power signal when safe, preventing device damage before it occurs
Solution Approach 2:
The system uses detection circuits to continuously monitor the powered device state and provides feedback to the power transmission control. Based on the feedback about device type and power state, the system dynamically adjusts whether to transmit power signal, ensuring safe operation while managing complexity through automated feedback-based control
2Reliability
If the power sourcing equipment detects device type and power state, then power can be supplied safely, but the system complexity increases due to additional detection circuits and control logic
Solution Approach 1:
The detection circuit serves multiple functions: it detects powered device type (PoC device vs. non-PoC device), detects power state (powered by external supply or not), and provides feedback for power transmission control. By making the detection circuit multi-functional, the patent reduces the need for separate dedicated circuits for each detection task, thereby managing complexity while achieving comprehensive safety
Solution Approach 2:
The powered device itself provides detection information through its electrical characteristics (such as impedance, power consumption patterns, or communication signals) that the detection circuit analyzes. The device essentially serves its own identification and status reporting function, reducing the need for complex active sensing mechanisms in the power sourcing equipment
3Duration of action of stationary object
If the power sourcing equipment supplies power signal continuously, then powered devices can operate without interruption, but power may be wasted when devices are disconnected or do not require power
Solution Approach 1:
Instead of continuous power transmission, the system periodically detects the powered device state (connection status, power requirements) and transmits power signal only when needed. This periodic detection and conditional power transmission reduces energy waste while ensuring continuous operation when required, balancing duration of action with energy efficiency
Data Source
AI summary
A power sourcing equipment is provided. The power sourcing equipment may include an input terminal, an output terminal, a switch, and a device detection circuit. The input terminal may receive a power signal. The output terminal may be electrically coupled to a powered device via a coaxial cable, which transmits the power signal from the power sourcing equipment to the powered device or a data signal from the powered device to the power sourcing equipment. The switch may control an electrical connection between the input and output terminal(s). The device detection circuit may detect whether the data signal is being transmitted from the powered device to the power sourcing equipment. If the data signal is not being transmitted from the powered device to the power sourcing equipment, the device detection circuit may control an operation of the switch based on an electrical parameter associated with the powered device.