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US4958255A
Expired / Lapsed
US
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Electrostatic discharge and electromagnetic interference protection circuit
Assignee: HP Inc
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Filing: 1988-12-28
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Granted: 1990-09-18
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Expires: 2008-12-28
Abstract
Abstract The protection circuit of the invention connects differentiated grounds in an electronic system either by a single diode, or by two diodes arranged in a back-to-back, parallel fashion. The differentiated grounds may include a chassis ground, a logic ground and an earth ground. The circuit locally connects two of the differentiated grounds, thereby providing a low inductance path for the fast discharging of electrostatic charge build-ups, with the diode(s) therein providing the electrical separation necessary to provide proper local isolation between the interconnected grounds to enable filtering out of electromagnetic interference potentials.
Inventors
- 👤 Thomas B. Pritchard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:26
CPC Classifications
H; H05; H05F; H05F3/00; H05F3/02
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
38 words
In an electronic system: a first ground; a second ground; and a conductive protection circuit including discharge means connected between said two grounds for conducting electrostatic discharge between said two grounds while providing isolation of electromagnetic interference potentials.
Claim 2
Dependent Claim
38 words
In an electronic system: a first ground; a second ground; and a conductive protection circuit including discharge means connected between said two grounds for conducting electrostatic discharge between said two grounds while providing isolation of electromagnetic interference potentials.
Claim 3
Dependent Claim
21 words
The circuit of claim 1, wherein one of said grounds is a logic ground and the other is a chassis ground.
Claim 4
Dependent Claim
18 words
The circuit of claim 1, wherein said discharge means comprises two diodes connected in a back-to-back, parallel fashion.
Claim 5
Dependent Claim
13 words
The circuit of claim 1, wherein said discharge means comprises a single diode.
Claim 6
Dependent Claim
17 words
The circuit of claim 1, wherein said discharge means is characterized bidirectionally by a preconduction threshold potential.
Claim 7
Dependent Claim
21 words
The circuit of claim 5, wherein one of said grounds is a logic ground and the other is a chassis ground.
Claim 8
Dependent Claim
18 words
The circuit of claim 5, wherein said discharge means comprises two diodes connected in a back-to-back, parallel fashion.
Claim 9
Dependent Claim
52 words
In an electronic system: a first node nominally bearing a predetermined electrical potential; a second node also nominally bearing such predetermined electrical potential; and a conductive protection circuit including discharge means connected between said nodes for conducting electrostatic discharge between said two nodes while providing isolation of electromagnetic interference between said nodes.
Claim 10
Dependent Claim
52 words
In an electronic system: a first node nominally bearing a predetermined electrical potential; a second node also nominally bearing such predetermined electrical potential; and a conductive protection circuit including discharge means connected between said nodes for conducting electrostatic discharge between said two nodes while providing isolation of electromagnetic interference between said nodes.
Claim 11
Dependent Claim
18 words
The circuit of claim 8, wherein said discharge means comprises two diodes connected in a back-to-back, parallel fashion.
Claim 12
Dependent Claim
13 words
The circuit of claim 8, wherein said discharge means comprises a single diode.
Claim 13
Dependent Claim
17 words
The circuit of claim 8, wherein said discharge means is characterized bidirectionally by a preconduction threshold potential.
Claim 14
Dependent Claim
18 words
The circuit of claim 11, wherein said discharge means comprises two diodes connected in a back-to-back, parallel fashion.
Claim 15
Dependent Claim
56 words
In an electronic system: an output signal conductor; system logic block means for producing a signal on said conductor; a first ground conductively connected to said system logic block means; a filter conductively connected to said conductor, including a second ground; and back-to-back diodes conductively connected in a parallel fashion between said first and second grounds.
Claim 16
Dependent Claim
56 words
In an electronic system: an output signal conductor; system logic block means for producing a signal on said conductor; a first ground conductively connected to said system logic block means; a filter conductively connected to said conductor, including a second ground; and back-to-back diodes conductively connected in a parallel fashion between said first and second grounds.
Claim 17
Dependent Claim
20 words
The circuit of 13, wherein said first ground is a logic ground and said second ground is a chassis ground.
Claim 18
Dependent Claim
20 words
The circuit of 13, wherein said first ground is a logic ground and said second ground is a chassis ground.
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) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |