Patent US5386188A successfully refreshed from Google Patents.
US5386188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
In-circuit current measurement
Assignee: Keithley Instruments LLC
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Filing: 1993-01-15
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Granted: 1995-01-31
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Expires: 2013-01-15
Abstract
Abstract A current in a circuit is measured without breaking the circuit. A relatively low resistance element in the circuit such as a component lead is chosen. A current is forced through the element and the voltage drop measured. Another current is forced through the element and the voltage drop measured. The values of these currents and voltages are used to determine the original current in the circuit.
Inventors
- 👤 Michael Minneman
- 👤 Kenneth A. Reindel
- 👤 John G. Banaska
- 👤 Gary K. Bish
- 👤 Andy J. Creque
- 👤 Michael Atwell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:50
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/2801; G01R31/2818; G01R19/00; G01R19/0092; G01R1/00; G01R1/20; G01R1/203; G01R27/00; G01R27/02; G01R27/16
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
260 words
A method for measuring current I 0 in a circuit, comprising: selecting an element in said circuit having a low resistance with respect to a remainder of the circuit, said element remaining connected in said circuit; connecting a current source in parallel with said element, said current source having an output current and a current control input for controlling said output current; connecting a voltage measuring device in parallel with both said element and said current source, said voltage measuring device having a voltage measurement output for providing a voltage measurement across said element and a voltage measurement control input for controlling said voltage measurement; providing a control device connected to said current control input and said voltage measurement control input; providing a calculation device having a calculation control input connected to said control device; driving a first current I 1 through the element with said current source and measuring a first voltage V 1 across the element with said measuring device, all in response to said control device, said first current being at or near zero; driving a second current I 2 through the element with said current source and measuring a second voltage V 2 across the element with said measuring device, all in response to said control device, said second current being greater than said first current; calculating a value for the current I 0 with said calculation device in response to said control device according to ##EQU8## providing the calculated value to a user or to an automated test system in response to said control device.
Claim 2
Independent Claim
260 words
A method for measuring current I 0 in a circuit, comprising: selecting an element in said circuit having a low resistance with respect to a remainder of the circuit, said element remaining connected in said circuit; connecting a current source in parallel with said element, said current source having an output current and a current control input for controlling said output current; connecting a voltage measuring device in parallel with both said element and said current source, said voltage measuring device having a voltage measurement output for providing a voltage measurement across said element and a voltage measurement control input for controlling said voltage measurement; providing a control device connected to said current control input and said voltage measurement control input; providing a calculation device having a calculation control input connected to said control device; driving a first current I 1 through the element with said current source and measuring a first voltage V 1 across the element with said measuring device, all in response to said control device, said first current being at or near zero; driving a second current I 2 through the element with said current source and measuring a second voltage V 2 across the element with said measuring device, all in response to said control device, said second current being greater than said first current; calculating a value for the current I 0 with said calculation device in response to said control device according to ##EQU8## providing the calculated value to a user or to an automated test system in response to said control device.
Claim 3
Dependent Claim
14 words
A method according to claim 1, wherein all of said currents are direct current.
Claim 4
Dependent Claim
18 words
A method according to claim 1, wherein said element is a printed circuit trace or a portion thereof.
Claim 5
Dependent Claim
17 words
A method according to claim 1, wherein said element is a component lead or a portion thereof.
Claim 6
Dependent Claim
16 words
A method according to claim 1, wherein said element is a wire or a portion thereof.
Claim 7
Dependent Claim
17 words
A method according to claim 1, wherein said element has a resistance of less than 10 ohms.
Claim 8
Dependent Claim
14 words
A method according to claim 6, wherein V 1 is less than 0.2 volts.
Claim 9
Independent Claim
267 words
A method for measuring current I 0 in a circuit, comprising: selecting an element in said circuit having a low resistance with respect to a remainder of the circuit, said element remaining connected in said circuit; connecting a current source in parallel with said element, said current source having an output current and a current control input for controlling said output current; connecting a voltage measuring device in parallel with both said element and said current source, said voltage measuring device having a voltage measurement output for providing a voltage measurement across said element and a voltage measurement control input for controlling said voltage measurement; providing a control device connected to said current control input and said voltage measurement control input; providing a calculation device having a calculation control input connected to said control device; measuring an initial voltage V 0 across the element in response to said measuring device; driving a first current I 1 through the element with said current source and measuring a first voltage V 1 across the element with said measuring device, all in response to said control device; driving a second current I 2 through the element with said current source and measuring a second voltage V 2 across the element with said measuring device, all in response to said control device, said second current being greater than said first current; calculating a value for the current I 0 with said calculation device in response to said control device according to ##EQU9## providing the calculated value to a user or to an automated test system in response to said control device.
Claim 10
Independent Claim
267 words
A method for measuring current I 0 in a circuit, comprising: selecting an element in said circuit having a low resistance with respect to a remainder of the circuit, said element remaining connected in said circuit; connecting a current source in parallel with said element, said current source having an output current and a current control input for controlling said output current; connecting a voltage measuring device in parallel with both said element and said current source, said voltage measuring device having a voltage measurement output for providing a voltage measurement across said element and a voltage measurement control input for controlling said voltage measurement; providing a control device connected to said current control input and said voltage measurement control input; providing a calculation device having a calculation control input connected to said control device; measuring an initial voltage V 0 across the element in response to said measuring device; driving a first current I 1 through the element with said current source and measuring a first voltage V 1 across the element with said measuring device, all in response to said control device; driving a second current I 2 through the element with said current source and measuring a second voltage V 2 across the element with said measuring device, all in response to said control device, said second current being greater than said first current; calculating a value for the current I 0 with said calculation device in response to said control device according to ##EQU9## providing the calculated value to a user or to an automated test system in response to said control device.
Claim 11
Dependent Claim
14 words
A method according to claim 8, wherein all of said currents are direct currents.
Claim 12
Dependent Claim
18 words
A method according to claim 8, wherein said element is a printed circuit trace or a portion thereof.
Claim 13
Dependent Claim
17 words
A method according to claim 8, wherein said element is a component lead or a portion thereof.
Claim 14
Dependent Claim
16 words
A method according to claim 8, wherein said element is a wire or a portion thereof.
Claim 15
Dependent Claim
17 words
A method according to claim 8, wherein said element has a resistance of less than 10 ohms.
Claim 16
Dependent Claim
14 words
A method according to claim 13, wherein V 0 is less than 0.2 volts.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |