Abstract: Circuitry and methodology for providing data transmission in a Power over Ethernet (PoE) system having a Power Sourcing Equipment (PSE) for providing power to a PoE link, and a Powered Device (PD) coupled to the PoE link for receiving the power from the PSE. The PSE and PD support data communication with each other in a common mode between two pairs of lines in an Ethernet twisted pair cable.

Abstract: A system for providing power to a load, having first and second power supply inputs respectively responsive to first and second input signals from first and second power supply sources to supply power to the load. For example, the first power supply input may be configured for supplying the load with power received from a communication link, such as an Ethernet link, and the second power supply input may be configured for supplying the load with power from an auxiliary power source. A power converter is provided to produce an output signal for supplying power to the load in response to the second input signal. The power converter is controlled to produce the output signal in accordance with a value of the first input signal.

Abstract: A system for providing power to a powered device over a communication cable has a cable resistance measuring mechanism that determines values of response signals detected in response to supplying each of at least three reference signals over the communication cable, and determines the resistance of a pair of wires in the cable based on these values. The cable resistance measuring mechanism may be configured for determining resistance of an Ethernet cable that delivers power to the powered device in a Power over Ethernet system.

Abstract: A system for providing power to a load, having first and second power supply inputs respectively responsive to first and second input signals from first and second power supply sources to supply power to the load. For example, the first power supply input may be configured for supplying the load with power received from a communication link, such as an Ethernet link, and the second power supply input may be configured for supplying the load with power from an auxiliary power source. A power converter is provided to produce an output signal for supplying power to the load in response to the second input signal. The power converter is controlled to produce the output signal in accordance with a value of the first input signal.

Abstract: A system for providing power to a load, having first and second power supply inputs respectively responsive to first and second input signals from first and second power supply sources to supply power to the load. For example, the first power supply input may be configured for supplying the load with power received from a communication link, such as an Ethernet link, and the second power supply input may be configured for supplying the load with power from an auxiliary power source. A power converter is provided to produce an output signal for supplying power to the load in response to the second input signal. The power converter is controlled to produce the output signal in accordance with a value of the first input signal.

Abstract: Novel system and methodology for detecting a Powered Device (PD) in a Power over Ethernet (PoE) system. A PD probing circuit generates a detection signal supplied to the PD and determines a PD response signal produced in response to the detection signal. Based on the PD response signal, the control circuit determines a detection value for identifying the PD. In particular, the control circuit concludes that the PD is a device satisfying a PoE standard if the detection value is in a first predetermined range, and concludes that the PD is a legacy PD device if the detection value is in a second predetermined range outside of the first predetermined range.

Abstract: A system for providing power to a powered device over a communication cable has a cable resistance measuring mechanism that determines values of response signals detected in response to supplying each of at least three reference signals over the communication cable, and determines the resistance of a pair of wires in the cable based on these values. The cable resistance measuring mechanism may be configured for determining resistance of an Ethernet cable that delivers power to the powered device in a Power over Ethernet system.

Abstract: A novel system for supplying power to a powered device over a communication link, such as an Ethernet link, has a current control mechanism that combines low-side current control circuitry with high-side current control circuitry. The low-side current control circuitry is coupled to a low-side power supply line for controlling low-side current flowing in the low-side power supply line. The high-side current control circuitry is coupled to a high-side power supply line for controlling high-side current in the high-side power supply line.

Abstract: A novel system and methodology for controlling an output of Power Sourcing Equipment in a Power over Ethernet system based on a current limit threshold. The PSE has an auto-zero circuit for comparing a monitored output current of the PSE with the current limit threshold to control the output of the PSE.

Abstract: Novel circuitry and methodology for detecting a Powered Device (PD) in a system for providing power to the PD. PD detection circuitry detects the PD in a first mode by providing detection current to probe the PD, and in a second mode by providing detection voltage to probe the PD. A control circuit determines that the PD is a valid device if the PD is detected both in the first mode and in the second mode.

Abstract: Novel system and methodology for distinguishing a Network Interface Card (NIC) from a short circuit condition in a Power over Ethernet (PoE) system. A system for providing power to a powered device (PD) includes a PD probing circuit that generates a detection signal supplied to a device being probed and determines a response signal produced in response to the detection signal, and a control circuit that determines a detection value based on the response signal. The control circuit detects a short circuit if the detection value is in a first predetermined range, and detects a NIC if the detection value is in a second predetermined range outside of the first predetermined range.

Abstract: A power management mechanism for a multi-port IEEE 802.3af-compliant Power Sourcing Equipment (PSE) device supplying power to multiple links. The power management mechanism has an analog bus shared by PSE controllers for receiving current proportional to amount of power demanded by a respective link. A comparator associated with a PSE controller compares a bus voltage proportional to a total amount of power demanded from the system with a predetermined value indicating the maximum power demand that can be supported by the controller, in order to determine whether to provide power to a newly detected Powered Device (PD) requesting power. The PSE controller provides the PD with a demanded amount of power if the voltage of the bus does not exceed the predetermined value, and denies a request of the PD for power if the voltage exceeds the predetermined value.