Detecting aircraft 28V discrete inputs
AssigneeHamilton Sundstrand Corporation
InventorRicha Verma
Life of this patent
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Abstract
A circuit for detecting discrete inputs includes a first line replaceable unit (LRU). A second LRU includes an LRU circuit that includes a power source, a diode set coupled to the power source, a resistor R3 connecting from a node Vc between the diode set and the first LRU to ground, and a logic detection and processing circuit. The logic detection and processing circuit is operably connected to the diode set, and is configured to detect a state of the first LRU based on a detected voltage. The detected voltage is either open, or 28-Volts.
Claims20
A circuit for detecting discrete inputs, the circuit comprising:
- a first line replaceable unit (LRU);
- and
- a second LRU including an LRU circuit, the LRU circuit including:
- a power source;
- a diode set coupled to the power source;
- a first resistor connecting from a node to ground, wherein the node is in series between the diode set and the first LRU;
- and
- a logic detection and processing circuit operably connected to the diode set and configured to detect a state of the first LRU based on a detected voltage, wherein the detected voltage is either open or 28-Volts;
- and
- wherein the diode set includes at least a first Zener diode and a second Zener diode connected in series with one another and connected in series between the power source and the logic detection and processing circuit, the second Zener diode having an anode connected to the logic detection and processing circuit.
A method comprising:
- detecting a state of a line replaceable unit (LRU) using a logic detection and processing circuit;
- providing power to a circuit;
- receiving a discrete input;
- detecting, by the logic detection and processing circuit, the discrete input over a path that maintains a constant voltage, wherein the discrete input is either open or 28-Volts;
- and
- processing, by the logic detection and processing circuit, the discrete input;
- wherein processing the discrete input comprises determining that the discrete input is open by detecting, using the logic detection and processing circuit, voltage that is below a specified threshold at a first node, the voltage at the first node based on leakage current multiplied by a resistance of a first resistor that connects between the first node and ground, the leakage current including a sum of leakage currents in the logic detection and processing circuit and at least two Zener diodes in the path, one of the at least two Zener diodes having an anode connected to the logic detection and processing circuit at the first node.
Dependencies are inferred from the claim text.