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Patent US4613767A successfully refreshed from Google Patents.
US4613767A
Expired / Lapsed
US
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Low forward-voltage drop SCR
Assignee: Unitrode Corp
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Filing: 1983-10-31
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Granted: 1986-09-23
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Expires: 2003-10-31
Abstract
Abstract An SCR having a reduced forward-voltage drop comprising an independently powered latch circuit driving an output transistor in combination with an additional turn-off transistor. The SCR provides saturated operation of the output transistor and self-commutation which allows for the SCR to turn-off. The present invention is particularly suitable for use in integrated circuit structures having additional circuit functions thereon.
Inventors
- 👤 Varnum S. Holland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:32
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/56; H03K17/72; H03K17/73
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
104 words
A low forward voltage drop SCR, comprising: a latch having an on and an off state providing a latch output signal when in the on state; an output transistor operable in response to said latch output signal and including a saturated condition; and means to turn off said latch when said output transistor is saturated, wherein said output transistor is one of an NPN and a PNP transistor, and said means to turn off said latch comprises a second transistor complementary to said output transistor, wherein said second transistor provides a current flow to turn off said latch when said output transistor is saturated.
Claim 2
Dependent Claim
104 words
A low forward voltage drop SCR, comprising: a latch having an on and an off state providing a latch output signal when in the on state; an output transistor operable in response to said latch output signal and including a saturated condition; and means to turn off said latch when said output transistor is saturated, wherein said output transistor is one of an NPN and a PNP transistor, and said means to turn off said latch comprises a second transistor complementary to said output transistor, wherein said second transistor provides a current flow to turn off said latch when said output transistor is saturated.
Claim 3
Dependent Claim
49 words
The SCR of claim 1, wherein said latch includes a plurality of transistors connected to provide positive feedback therein, having a loop gain in excess of unity; and said second transistor current is operable to reduce said loop gain to less than unity, causing said latch to turn off.
Claim 4
Dependent Claim
75 words
The SCR of claim 1, including a first material comprising an emitter region of said output transistor emitter; a second material comprising a base region of said output transistor and an emitter region of said second transistor; a third material comprising a collector region of said output transistor and a base region of said second transistor; and a fourth material comprising a collector region of said second transistor, being electrically connected to said first material.
Claim 5
Dependent Claim
34 words
The SCR of claim 3, wherein said second transistor is a parasitic transistor formed to include the structure of said output transistor, wherein said fourth material is an isolation barrier for said output transistor.
Claim 6
Dependent Claim
33 words
The SCR of claim 2, wherein said second transistor and said output transistor are included in a portion of an integrated circuit, and said plurality of latch transistors are external to said portion.
Claim 7
Dependent Claim
14 words
The SCR of claim 5, wherein said plurality of latch transistors are discrete transistors.
Claim 8
Independent Claim
67 words
A method of providing a low forward-voltage drop SCR comprising the steps of: latching a circuit into an on state; providing a latch signal when said circuit is on; saturating an output transistor according to said latch signal; receiving excess carriers produced by said output transistor when saturated; providing a current flow in reponse to said excess carriers; and unlatching said circuit according to said current flow.
Claim 9
Independent Claim
67 words
A method of providing a low forward-voltage drop SCR comprising the steps of: latching a circuit into an on state; providing a latch signal when said circuit is on; saturating an output transistor according to said latch signal; receiving excess carriers produced by said output transistor when saturated; providing a current flow in reponse to said excess carriers; and unlatching said circuit according to said current flow.
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) | 1989-09-22 | 1990-03-24 | 1990-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-22 | 1994-03-24 | 1994-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-22 | 1998-03-24 | 1998-09-23 | $7700.00 | Window Closed / Lapsed |