Abstract: One or more Power Sourcing Equipment (PSE) are coupled to points in a network of interconnected nodes. Each node has a first port and a second port. Assume the first port of a first node is receiving DC power from the PSE. The first node, at its second port, then detects an electrical signature from a first port of an adjacent second node. If the proper electrical signature is presented by the adjacent second node, the powered first node closes a switch to pass power between its first port and second port to power the second node via the first port of the second node. All nodes in the network are then sequentially powered up in this manner. If there is a fault between the first node and the second node, the second node will be powered by another node connected to the second port of the second node.

Abstract: The invention pertains to systems where DC power is supplied by a PSE to a PD, such as over differential data wire pairs. IEEE standards require a minimum current to be drawn from the PD in order for the PSE to continue supplying the DC voltage. If the PD is in a low power mode, the PSE will normally discontinue supplying the DC voltage, which then requires a new detection and classification routine for powering up again. To avoid this, a “maintain power signature” controller provides a periodic current pulse by a current source connected between the PD input and the PD's full bridge rectifier. Any droop in the DC voltage that reverse biases the full bridge rectifier while the PD is in its low power mode will not affect the current pulse, so the PSE continues to supply the DC voltage.

Abstract: In one embodiment, a PoDL system includes a PSE that uses high side and low side circuit breakers that uncouple the PSE voltage source from the wire pair in the event that a fault is detected. Faults may include a temporary short to ground, or to a battery voltage, or between the wires. The breakers perform an automatic retry operation in the event the fault has been removed. The voltages on the wires in the wire pair may be monitored to determine whether the voltages are within a normal range or indicative of a fault condition. Other embodiments are disclosed.

Abstract: Circuits and techniques are described for detecting a ground fault leak between the PSE and the PD. Prior to PoDL voltage being applied to the PD, a test switch is temporarily closed for sensing a voltage drop in a loop between the positive terminal of the PSE voltage source and any ground leakage path between the PSE and the PD. If the resistance of the ground leakage path is below a certain threshold, a fault is declared. A similar test may be performed without a test switch by supplying a known test current through the loop and sensing the voltage drop. Another test is to connect the positive terminal of the PSE voltage source to the loop and sense the resulting current. After the full PoDL voltage is applied to the PD, a ground fault may be detected by sensing the equivalence between the source and return PSE currents.

Abstract: One or more Power Sourcing Equipment (PSE) are coupled to points in a network of interconnected nodes. Each node has a first port and a second port. Assume the first port of a first node is receiving DC power from the PSE. The first node, at its second port, then detects an electrical signature from a first port of an adjacent second node. If the proper electrical signature is presented by the adjacent second node, the powered first node closes a switch to pass power between its first port and second port to power the second node via the first port of the second node. All nodes in the network are then sequentially powered up in this manner. If there is a fault between the first node and the second node, the second node will be powered by another node connected to the second port of the second node.

Abstract: A Power Over Data Lines (PoDL) system includes Power Sourcing Equipment (PSE) supplying DC power and differential Ethernet data over a single twisted wire pair to a Powered Device (PD). Due to start-up perturbations, PD load current variations, and other causes, dV/dt noise is introduced in the power signal. Such noise may be misinterpreted as data unless mitigated somehow. Rather than increasing the values of the passive filtering components conventionally used for decoupling/coupling the power and data from/to the wire pair, active circuitry is provided in the PSE, PD, or both to limit dV/dt in the power signal. Such circuitry may be implemented on the same chip as the PSE controller or PD controller. Therefore, the sizes of the passive components in the decoupling/coupling networks may be reduced.

Abstract: The invention pertains to systems where DC power is supplied by a PSE to a PD, such as over differential data wire pairs. IEEE standards require a minimum current to be drawn from the PD in order for the PSE to continue supplying the DC voltage. If the PD is in a low power mode, the PSE will normally discontinue supplying the DC voltage, which then requires a new detection and classification routine for powering up again. To avoid this, a “maintain power signature” controller provides a periodic current pulse by a current source connected between the PD input and the PD's full bridge rectifier. Any droop in the DC voltage that reverse biases the full bridge rectifier while the PD is in its low power mode will not affect the current pulse, so the PSE continues to supply the DC voltage.

Abstract: In one embodiment, a PoDL system includes a PSE that uses high side and low side circuit breakers that uncouple the PSE voltage source from the wire pair in the event that a fault is detected. Faults may include a temporary short to ground, or to a battery voltage, or between the wires. The breakers perform an automatic retry operation in the event the fault has been removed. The voltages on the wires in the wire pair may be monitored to determine whether the voltages are within a normal range or indicative of a fault condition. Other embodiments are disclosed.

Abstract: Circuits and techniques are described for detecting a ground fault leak between the PSE and the PD. Prior to PoDL voltage being applied to the PD, a test switch is temporarily closed for sensing a voltage drop in a loop between the positive terminal of the PSE voltage source and any ground leakage path between the PSE and the PD. If the resistance of the ground leakage path is below a certain threshold, a fault is declared. A similar test may be performed without a test switch by supplying a known test current through the loop and sensing the voltage drop. Another test is to connect the positive terminal of the PSE voltage source to the loop and sense the resulting current. After the full PoDL voltage is applied to the PD, a ground fault may be detected by sensing the equivalence between the source and return PSE currents.

Abstract: A Power Over Data Lines (PoDL) system includes Power Sourcing Equipment (PSE) supplying DC power and differential Ethernet data over a single twisted wire pair to a Powered Device (PD). Due to start-up perturbations, PD load current variations, and other causes, dV/dt noise is introduced in the power signal. Such noise may be misinterpreted as data unless mitigated somehow. Rather than increasing the values of the passive filtering components conventionally used for decoupling/coupling the power and data from/to the wire pair, active circuitry is provided in the PSE, PD, or both to limit dV/dt in the power signal. Such circuitry may be implemented on the same chip as the PSE controller or PD controller. Therefore, the sizes of the passive components in the decoupling/coupling networks may be reduced.

Abstract: Microbolometer circuitry and methods are disclosed to allow an individual microbolometer or groups of microbolometers, such as a microbolometer focal plane array, to operate over a wide temperature range. Temperature compensation is provided, such as through circuitry and/or calibration methods, to reduce non-uniform behavior over the desired operating temperatures. For example, the relative mismatch in the temperature coefficient of resistance of an active microbolometer and a reference microbolometer is compensated by employing a variable resistor in series with the active microbolometer. The variable resistor can be calibrated over the desired temperature range to minimize the affect of the relative mismatch. Various other circuit implementations, calibration methods, and processing of the microbolometer circuit output can be employed to provide further compensation.

Abstract: Microbolometer circuitry and methods are disclosed to allow an individual microbolometer or groups of microbolometers, such as a microbolometer focal plane array, to operate over a wide temperature range. Temperature compensation is provided, such as through circuitry and/or calibration methods, to reduce non-uniform behavior over the desired operating temperatures. For example, the relative mismatch in the temperature coefficient of resistance of an active microbolometer and a reference microbolometer is compensated by employing a variable resistor in series with the active microbolometer. The variable resistor can be calibrated over the desired temperature range to minimize the affect of the relative mismatch. Various other circuit implementations, calibration methods, and processing of the microbolometer circuit output can be employed to provide further compensation.

Abstract: A dual sample-and-hold architecture in each unit cell of a read-in-integrated-circuit (RIIC) provides maximum frame rate without frame overlap. Analog pixel signals are updated sequentially in one sample-and-hold capacitor, while an emitter element displays a pixel of a display frame in response to a stored analog signal voltage on an isolated second sample-and-hold capacitor. After all unit cells are updated, the signals on the two capacitors are combined, updating all emitter elements for the next frame. A voltage mode amplifier as an emitter driver provides a more nearly linear dependence of infrared power output on signal voltage than do previous transconductance amplifiers. A digital to analog converter (DAC) on the RIIC substrate results in a simplified interface to the RIIC and in an increased immunity to noise.