Patent US4538198A successfully refreshed from Google Patents.
US4538198A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protection circuit for an output transistor
Assignee: Toshiba Corp
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Filing: 1984-07-21
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Granted: 1985-08-27
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Expires: 2004-07-21
Abstract
Abstract A protection circuit for an output transistor which produces a protecting signal representing the power consumption of the output transistor, namely the product of collector current and collector to emitter voltage of the output transistor, thereby protecting the output transistor over a broad operating range.
Inventors
- 👤 Kazuo Imanishi
- 👤 Masaru Hashimoto
- 👤 Makoto Mori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:43
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
263 words
A protection circuit for an output transistor having a base electrode, an emitter electrode, and a collector electrode, comprising: a first terminal coupled to the collector electrode of said output transistor; a second terminal coupled to the emitter electrode of said output terminal; a first transistor having a base electrode, an emitter electrode and a collector electrode; first means for connecting the base electrode of said first transistor to the base electrode of said output transistor; first resistor means coupled between said emitter electrode and said second terminal for reducing a collector current of said first transistor; second means comprising first diode means and second resistor means for connecting said collector electrode of said first transistor to said first terminal for producing a voltage being equal to the base to emitter voltage of said output transistor; a second transistor having a base electrode, an emitter electrode and a collector electrode; third means for connecting the base electrode of said second transistor to the collector electrode of said first transistor; fourth means for connecting the collector electrode of said second transistor to said first terminal; third resistor means coupled between said emitter electrode of said second transistor and said second terminal; a fourth transistor having a base electrode, an emitter electrode and a collector electrode; fifth means for connecting the base electrode of said fourth transistor to the emitter electrode of said third transistor; and second diode means coupled between said emitter electrode of said third transistor and said first terminal, thereby producing a protecting signal from the collector electrode of said third transistor.
Claim 2
Dependent Claim
263 words
A protection circuit for an output transistor having a base electrode, an emitter electrode, and a collector electrode, comprising: a first terminal coupled to the collector electrode of said output transistor; a second terminal coupled to the emitter electrode of said output terminal; a first transistor having a base electrode, an emitter electrode and a collector electrode; first means for connecting the base electrode of said first transistor to the base electrode of said output transistor; first resistor means coupled between said emitter electrode and said second terminal for reducing a collector current of said first transistor; second means comprising first diode means and second resistor means for connecting said collector electrode of said first transistor to said first terminal for producing a voltage being equal to the base to emitter voltage of said output transistor; a second transistor having a base electrode, an emitter electrode and a collector electrode; third means for connecting the base electrode of said second transistor to the collector electrode of said first transistor; fourth means for connecting the collector electrode of said second transistor to said first terminal; third resistor means coupled between said emitter electrode of said second transistor and said second terminal; a fourth transistor having a base electrode, an emitter electrode and a collector electrode; fifth means for connecting the base electrode of said fourth transistor to the emitter electrode of said third transistor; and second diode means coupled between said emitter electrode of said third transistor and said first terminal, thereby producing a protecting signal from the collector electrode of said third transistor.
Claim 3
Dependent Claim
28 words
A protection circuit for an output transistor according to claim 1, wherein the emitter area of said first transistor is formed smaller than that of said output transistor.
Claim 4
Dependent Claim
192 words
A protection circuit for an output transistor having a base electrode, an emitter electrode and a collector electrode, comprising: a first terminal coupled to the collector electrode of said output transistor; a second terminal coupled to the emitter electrode of said output transistor; a first transistor having a base electrode, an emitter electrode and a collector electrode; first means for connecting the base electrode of said first transistor to the base electrode of said output transistor; first resistor means coupled between said emitter electrode of said first transistor and said second terminal for reducing a collector current of said first transistor; a second transistor having a base electrode, an emitter electrode and a collector electrode; second resistor means coupled between said collector electrodes of said first transistor and the emitter electrode of said second transistor; second means for connecting the collector electrode of said second transistor to said first terminal; first diode means coupled between said base electrode of said second transistor and said first terminal; third resistor means coupled between said first diode means and said second terminal; output signal producing means connected to the collector electrode of said first transistor.
Claim 5
Dependent Claim
192 words
A protection circuit for an output transistor having a base electrode, an emitter electrode and a collector electrode, comprising: a first terminal coupled to the collector electrode of said output transistor; a second terminal coupled to the emitter electrode of said output transistor; a first transistor having a base electrode, an emitter electrode and a collector electrode; first means for connecting the base electrode of said first transistor to the base electrode of said output transistor; first resistor means coupled between said emitter electrode of said first transistor and said second terminal for reducing a collector current of said first transistor; a second transistor having a base electrode, an emitter electrode and a collector electrode; second resistor means coupled between said collector electrodes of said first transistor and the emitter electrode of said second transistor; second means for connecting the collector electrode of said second transistor to said first terminal; first diode means coupled between said base electrode of said second transistor and said first terminal; third resistor means coupled between said first diode means and said second terminal; output signal producing means connected to the collector electrode of said first transistor.
Claim 6
Dependent Claim
28 words
A protection circuit for an output transistor according to claim 3, wherein the emitter area of said first transistor is formed smaller than that of said output transistor.
References Cited (Backward Citations)
US4355341A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-08-26 | 1989-02-25 | 1989-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-26 | 1993-02-25 | 1993-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-26 | 1997-02-25 | 1997-08-27 | $7700.00 | Window Closed / Lapsed |