Discrete voltage/ open input
AssigneeHamilton Sundstrand Corporation
InventorsBrennan Fox, Lon R. Hoegberg
Life of this patent
Estimating the term…
Abstract
An input circuit includes an input line for providing input regarding state of a supply at a first node. An impedance is connected to the input line at a second node for connecting the input line to ground. A Zener diode can be connected in the input line in series between the first and second nodes to impede current flowing through the Zener diode below the Zener voltage thereof in a direction from the first node to the second node, and to allow current above the Zener voltage thereof in the direction from the first node to the second node, wherein the input line is free of any node connecting a power voltage source to the input line between the first and second nodes.
Claims13
An input circuit comprising:
- an input line for providing input regarding state of a supply at a first node;
- a main grounding impedance connected to the input line at a second node for connecting the input line to ground, and wherein the input line is free of any node connecting a power voltage source to the input line between the first and second nodes;
- a Zener diode connected in the input line in series between the first and second nodes to impede current flowing through the Zener diode below the Zener voltage thereof in a direction from the first node to the second node, and to allow current above the Zener voltage thereof in the direction from the first node to the second node;
- a third node in the input line between the Zener diode and the first node;
- a fourth node in the input line between the Zener diode and the third node;
- a first impedance connected in series between the third node and the fourth node;
- a clamp line connected to the third node and to the fourth node in parallel to the input line;
- a resistor connected in series in the clamp line between the third node and the fourth node;
- and
- a clamp diode connected in series in the clamp line between the resistor and the third node, wherein the clamp diode is oriented to ensure current through the clamp line does not flow in a direction from the third node to the fourth node for protecting the input line from transients from a supply connected to the first node.
A method of providing input from a supply to a logic device comprising:
- impeding current through an input line to a logic device with a Zener diode to ensure a logic low is input to the logic device when voltage across the Zener diode is below the Zener voltage of the Zener diode;
- and
- allowing current through the input line to ensure a logic high is input to the logic device when voltage across the Zener diode exceeds the Zener voltage of the Zener diode, without connecting a power voltage source to the input line between the Zener diode and a first node of the input line where the current is input into the input line.
Dependencies are inferred from the claim text.