Protection circuit for general-purpose digital I/O lines
First Claim
1. An apparatus comprising circuitry for protecting the apparatus from destructive electrical conditions, the apparatus comprising:
- one or more input/output (I/O) lines;
a first protection circuit coupled to an I/O line and operable to provide a primary level of protection for the I/O line, the first protection circuit comprising;
one or more diodes directly connected to the I/O line for voltage clamping, anda current limiting device coupled to the I/O line and to the one or more diodes, wherein the current limiting device is operable to function as a low impedance device in a normal operating range and to function as a controlled power dissipater outside of the normal operating range; and
a second protection circuit coupled to the first protection circuit and to the I/O line, wherein the second protection circuit is operable to provide a secondary level of protection for the I/O line, wherein the second protection circuit comprises one or more diodes directly connected to the I/O line for voltage clamping;
wherein the one or more diodes of the first protection circuit are coupled between the current limiting device and the one or more diodes of the second protection circuit;
wherein the one or more diodes comprised in the first protection circuit have a lower forward voltage drip compared to the one or more diodes comprised in the second protection circuit.
5 Assignments
0 Petitions
Accused Products
Abstract
A protection circuit for protecting a device from destructive electrical conditions, such as ESD, over-voltage, and over-current, while keeping the output impedance of the device'"'"'s I/O lines to a minimum, and self-regulating power dissipation. The device may comprise a first protection circuit and a second protection circuit coupled to each of one or more I/O lines for providing a primary and a secondary level of protection, respectively, for the I/O lines. The first protection circuit of the device may combine the use of Schottky diodes for voltage clamping, with a current limiting device for self-regulating the power dissipation. The current limiting device may be operable to function as a small, low impedance resistor in a normal operating range and as a controlled power dissipater outside the normal operating range. The device may be a data acquisition device comprised in a data acquisition system.
51 Citations
46 Claims
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1. An apparatus comprising circuitry for protecting the apparatus from destructive electrical conditions, the apparatus comprising:
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one or more input/output (I/O) lines; a first protection circuit coupled to an I/O line and operable to provide a primary level of protection for the I/O line, the first protection circuit comprising; one or more diodes directly connected to the I/O line for voltage clamping, and a current limiting device coupled to the I/O line and to the one or more diodes, wherein the current limiting device is operable to function as a low impedance device in a normal operating range and to function as a controlled power dissipater outside of the normal operating range; and a second protection circuit coupled to the first protection circuit and to the I/O line, wherein the second protection circuit is operable to provide a secondary level of protection for the I/O line, wherein the second protection circuit comprises one or more diodes directly connected to the I/O line for voltage clamping; wherein the one or more diodes of the first protection circuit are coupled between the current limiting device and the one or more diodes of the second protection circuit; wherein the one or more diodes comprised in the first protection circuit have a lower forward voltage drip compared to the one or more diodes comprised in the second protection circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A data acquisition device comprising circuitry to protect the device from destructive electrical conditions, the data acquisition device comprising:
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one or more input/output (I/O) lines; a first protection circuit coupled to an I/O line and operable to provide a primary level of protection for the I/O line, the first protection circuit comprising; one or more Schottky diodes directly connected to the I/O line for voltage clamping, and a current limiting device coupled to the I/O line and the one or more Schottky diodes, wherein the current limiting device is operable to function as a low impedance device in a normal operating range and to function as a controlled power dissipater outside of the normal operating range; and a second protection circuit coupled to the first protection circuit and to the I/O line, wherein the second protection circuit is operable to provide a secondary level of protection for the I/O line, the second protection circuit comprising one or more pn-junction diodes directly connected to the I/O line for voltage clamping; wherein the one or more Schottky diodes of the first protection circuit are coupled between the current limiting device and the one or more pn-junction diodes of the second protection circuit. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A data acquisition system, comprising:
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a computer system for processing data obtained from one or more data acquisition processes; and a data acquisition device coupled to the computer system for implementing the data acquisition processes and comprising circuitry to protect the device from destructive electrical conditions, the data acquisition device comprising; one or more input/output (I/O) lines; a first protection circuit coupled to an I/O line and operable to provide a primary level of protection for the I/O line, the protection circuit comprising; one or more Schottky diodes directly connected to the I/O line for voltage clamping, and a current limiting device coupled to the I/O line and the one or more Schottky diodes, wherein the current limiting device is operable to function as a low impedance device in a normal operating range and to function as a controlled power dissipater outside of the normal operating range; and a second protection circuit coupled to the first protection circuit and to the I/O line, wherein the second protection circuit is operable to provide a secondary level of protection for the I/O line, the second protection circuit comprising; one or more pn-junction diodes directly connected to the I/O line for voltage clamping; wherein the one or more Schottky diodes of the first protection circuit are coupled between the current limiting device and the one or more pn-junction diodes of the second protection circuit. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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33. An apparatus comprising circuitry for protecting the apparatus from destructive electrical conditions, the apparatus comprising:
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a plurality of input/output (I/O) lines; a first integrated circuit coupled to the plurality of I/O lines, wherein the first integrated circuit includes a plurality of first protection circuits, each first protection circuit coupled to a corresponding I/O line and operable to provide a primary level of protection for the I/O line, wherein each of the first protection circuits comprises; one or more diodes directly connected to the I/O line for voltage clamping, and a current limiting device coupled to the I/O line and to the one or more diodes, wherein the current limiting device is operable to function as a low impedance device in a normal operating range and to function as a controlled power dissipater outside of the normal operating range; and a second integrated circuit coupled to the first integrated circuit and to the I/O lines, wherein the second integrated circuit includes a plurality of second protection circuits, each second protection circuit coupled to a corresponding first protection circuit and I/O line and operable to provide a secondary level of protection for the I/O line, wherein each of the second protection circuits comprises one or more diodes directly connected to the I/O line for voltage clamping; wherein, for each first protection circuit and corresponding second protection circuit, the one or more diodes of the first protection circuit are coupled between the current limiting device and the one or more diodes of the second protection circuit; the one or more diodes comprised in the first protection circuit have a lower forward voltage drop compared to the one or more diodes comprised in the second protection circuit.
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34. An apparatus comprising circuitry for protecting the apparatus from destructive electrical conditions, the apparatus comprising:
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one or more input/output (I/O) lines; a first protection circuit coupled to an I/O line and operable to provide a primary level of protection for the I/O line, the first protection circuit comprising; one or more diodes connected to the I/O line for voltage clamping, and a current limiting device coupled to the I/O line and to the one or more diodes, wherein the current limiting device is operable to function as a low impedance device in a normal operating range and to function as a controlled power dissipater outside of the normal operating range; a second protection circuit coupled to the first protection circuit and to the I/O line, wherein the second protection circuit is operable to provide a secondary level of protection for the I/O line, wherein the second protection circuit comprises one or more diodes connected to the I/O line for voltage clamping; and a split I/O buffer coupled to the second protection circuit and to the I/O line, wherein the split I/O buffer is configured to control the I/O state of the I/O line; wherein the one or more diodes of the first protection circuit are coupled between the current limiting device and the one or more diodes of the second protection circuit. - View Dependent Claims (35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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Specification