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Patent US5021682A successfully refreshed from Google Patents.
US5021682A
Expired / Lapsed
US
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Instantaneous power limiting circuit
Assignee: National Semiconductor Corp
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Filing: 1989-05-11
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Granted: 1991-06-04
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Expires: 2009-05-11
Abstract
Abstract A DMOST driver circuit responds to the current flowing in the DMOST and the voltage appearing across it. The current and voltage are multiplied together in a g m amplifier which is coupled to drive a first input of a diff-amp. The diff-amp has its second input coupled to a source of reference potential. The diff-amp output is coupled to the DMOST gate to create a stabilizing negative feedback loop. The first diff-amp input is also coupled to a reference potential related threshold voltage so that the drive to the DMOST will be controlled by the DMOST power dissipation multiplied by a predetermined constant which is chosen to provide a safe dissipation level.
Inventors
- 👤 Stephen W. Hobrecht
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:31
CPC Classifications
H; H03; H03L; H03L1/00; H03F; H03F1/00; H03F1/52; H03F1/523; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0822
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
93 words
A circuit for limiting the power dissipation in a diffused metal oxide semiconductor transistor or DMOST, which passes a current therethrough and develops a voltage thereacross to a safe value, said circuit comprising: means for sensing the voltage across said DMOST; means for sensing the current passing through said DMOST; means for multiplying said voltage by said current to obtain a power dissipation related current; and means responsive to said dissipation related current to produce a control voltage that is coupled to said DMOST to limit said power dissipation to a safe value.
Claim 2
Dependent Claim
93 words
A circuit for limiting the power dissipation in a diffused metal oxide semiconductor transistor or DMOST, which passes a current therethrough and develops a voltage thereacross to a safe value, said circuit comprising: means for sensing the voltage across said DMOST; means for sensing the current passing through said DMOST; means for multiplying said voltage by said current to obtain a power dissipation related current; and means responsive to said dissipation related current to produce a control voltage that is coupled to said DMOST to limit said power dissipation to a safe value.
Claim 3
Dependent Claim
33 words
The circuit of claim 1 wherein said means for sensing the current comprise a resistor having a value that is small compared with the DMOST on resistance coupled in series with said DMOST.
Claim 4
Dependent Claim
20 words
The circuit of claim 1 wherein said means for sensing voltage comprise a resistor coupled in parallel with said DMOST.
Claim 5
Dependent Claim
12 words
The circuit of claim 2 wherein said resistor is composed of metal.
Claim 6
Dependent Claim
14 words
The circuit of claim 1 wherein said means for multiplying comprise a transconductance amplifier.
Claim 7
Dependent Claim
51 words
The circuit of claim 4 wherein said transconductance amplifier has a differential input that is connected to said means for sensing current and a common input that is connected to said means for sensing voltage whereby said transconductance amplifier output is a current that is proportional to voltage multiplied by current.
Claim 8
Dependent Claim
34 words
The circuit of claim 4 wherein said means for multiplying is a transconductance amplifier that has an inverse temperature coefficient of transconductance that offsets the positive temperature coefficient of resistance in said metal resistor.
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) | 1994-06-03 | 1994-12-03 | 1995-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-03 | 1998-12-03 | 1999-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-03 | 2002-12-03 | 2003-06-04 | $7700.00 | Window Closed / Lapsed |