Abstract: A technique for combining power to a single load from multiple power supplies using power over Ethernet (PoE) is disclosed. Each power supply is coupled to associated power sourcing equipment (PSE) providing PoE, and each PSE has a current limit. The power supplies supply approximately the same voltage, but the output voltages are typically not exactly equal. All the power supplies are connected via diodes to a common load terminal. The power supply outputting the highest voltage first supplies power to the load terminal, since only its diode is forward biased, until a PoE current limit is reached. Then its duty cycle is limited. The load terminal voltage is then inherently lowered to cause the diode of the power supply with the next highest output voltage to connect it to the load to supply additional power to the load as the first power supply continues to supply its limited current.

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: System and methodology for managing power supplied to powered devices over communication links, such as Ethernet links. A power supply system has multiple power supply ports for providing power to respective powered devices via multiple communication links. A power-in-use bus shared by the multiple power supply ports is configured for receiving a power-in-use signal representing total amount of power being used by the powered devices. Multiple port control circuits associated with the power supply ports are responsive to the power-in-use signal for controlling supply of power to the respective powered devices.

Abstract: Novel system and protocol for controlling a sequence of events. The sequencing system has a master circuit for providing sequencing information defining a sequence of events using a sequencing signal, and at least one slave circuit responsive to the sequencing signal for producing at least one event signal defining an event. The master and slave circuits are configured for providing a bidirectional transfer of the sequencing information via a single wire.

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 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: A novel system for providing power over the Ethernet includes a current limit circuit for preventing an output current from exceeding a current threshold set at a prescribed level, and a foldback circuit for reducing the current threshold when an output voltage is lower than a prescribed voltage value. The foldback circuit may be controlled to operate in a high-power mode to increase the current threshold above the prescribed level.

Abstract: System and methodology for supplying power to a load using a pass device for connecting the load. A current limit circuit prevents current supplied to the load from exceeding a current threshold. A foldback circuit modifies the current threshold in accordance with a prescribed condition. The foldback circuit is configured to vary the current threshold in accordance with an approximate safe operating area of the pass device.

Abstract: System and methodology for driving an inductive load using a pass device for providing hot swap connection to the load. A current limit circuit prevents current supplied to the load from exceeding a current threshold. A foldback circuit controls the current limit circuit to reduce the current threshold when a voltage across the pass device is above a prescribed value. A filter circuit is coupled to the foldback circuit for reducing oscillations when the inductive load is connected to the pass device.

Abstract: A system for supplying power to a load over a communication link has high-side current sensing circuitry for measuring a high-side current value, low-side current sensing circuitry for measuring a low-side current value, and control circuitry responsive to both the high-side current value and the low-side current value to detect a fault condition, detect information from the load, and/or transmit information to the load by creating a prescribed unbalance between the high-side current and the low-side current.

Abstract: A level shifting circuit and methodology involving a switching current generator responsive to switching of an input signal for producing a switching current to switch an output signal, and a holding current generator for producing a holding current to hold the logic level of the output signal in accordance with the logic level of the input signal. The holding current is produced independently of the switching current.

Abstract: System and methodology for driving an inductive load using a pass device for providing hot swap connection to the load. A current limit circuit prevents current supplied to the load from exceeding a current threshold. A foldback circuit controls the current limit circuit to reduce the current threshold when a voltage across the pass device is above a prescribed value. A filter circuit is coupled to the foldback circuit for reducing oscillations when the inductive load is connected to the pass device.

Abstract: System and methodology for supplying power to a load using a pass device for connecting the load. A current limit circuit prevents current supplied to the load from exceeding a current threshold. A foldback circuit modifies the current threshold in accordance with a prescribed condition. The foldback circuit is configured to vary the current threshold in accordance with an approximate safe operating area of the pass device.

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: An interface device connects a camcorder to a camera operating in the non-visible electromagnetic spectrum to form a portable unitary system. The interface device provides a mechanical connection between the camcorder and the camera. A video cable carries video image data from the camera to the camcorder. A control connection additionally may be provided between the camcorder and the camera through the interface device, to allow the camera to be controlled through controls on the camcorder itself. A power connection may be provided between the camcorder and the camera through the interface device, to allow the camera to draw power from the camcorder.