US4589049A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Protection circuit for integrated circuits
Assignee: Telefunken Electronic GmbH
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Filing: 1984-10-12
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Granted: 1986-05-13
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Expires: 2004-10-12
Abstract
Abstract A protection circuit for an integrated circuit that is connected across a power source includes a first transistor and a zener diode or equivalent circuit arrangement for causing the first transistor to conduct if the integrated circuit receives an excessive voltage from the power source. A measuring resistor is connected to the emitter of the first transistor, and a voltage drop appears across the measuring resistor if the first transistor conducts. A comparator is provided to compare the voltage across the measuring resistor to a reference voltage. The output of the comparator drives the base of a second transistor, the emitter of which is connected to the collector of the first transistor and the collector of which is connected to the base of the first transistor. Current through the second transistor renders the first transistor more conductive.
Inventors
- 👤 Gerhard Krumrein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:05
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/04; H02H9/041
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
133 words
A protection circuit for an integrated circuit, in particular, for integrated circuits for motor vehicles, said circuit comprising a first transistor having a collector, base, and emitter, a second transistor having a collector, base, and emitter, a comparator, a measuring resistor preceding the emitter of the first transistor, and means for causing the first transistor to conduct when the protection circuit is exposed to a predetermined voltage, wherein the voltage dropping at the measuring resistor is compared to a reference voltage by means of the comparator, wherein the output signal of the comparator drives the base of the second transistor, wherein the base of the first transistor is connected to the collector of the second transistor, and wherein the collector of the first transistor is connected to the emitter of the second transistor.
Claim 2
Dependent Claim
133 words
A protection circuit for an integrated circuit, in particular, for integrated circuits for motor vehicles, said circuit comprising a first transistor having a collector, base, and emitter, a second transistor having a collector, base, and emitter, a comparator, a measuring resistor preceding the emitter of the first transistor, and means for causing the first transistor to conduct when the protection circuit is exposed to a predetermined voltage, wherein the voltage dropping at the measuring resistor is compared to a reference voltage by means of the comparator, wherein the output signal of the comparator drives the base of the second transistor, wherein the base of the first transistor is connected to the collector of the second transistor, and wherein the collector of the first transistor is connected to the emitter of the second transistor.
Claim 3
Dependent Claim
42 words
A protection circuit according to claim 1, wherein the means for causing the first transistor to conduct comprises a circuit arrangement exhibiting the characteristics of a zener diode, the circuit arrangement being connected between the base and collector of the first transistor.
Claim 4
Dependent Claim
34 words
A protection circuit according to claim 2, wherein the circuit arrangement comprises the emitter base sections of a plurality of transistors connected in series between the base and the collector of the first transistor.
Claim 5
Dependent Claim
19 words
A protection circuit according to claim 3, wherein the circuit arrangement comprises the emitter base sections of three transistors.
Claim 6
Dependent Claim
15 words
A protection circuit according to claim 1, wherein a transistor is provided as the comparator.
Claim 7
Dependent Claim
20 words
A protection circuit according to claim 1, wherein the first transistor forms together with a further transistor a Darlington circuit.
Claim 8
Dependent Claim
31 words
A protection circuit according to claim 1, wherein the means for causing the first transistor to conduct comprises a zener diode connected between the base and collector of the first transistor.
References Cited (Backward Citations)
US3626249A
Cited
US4005342A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-12 | 1989-11-11 | 1990-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-12 | 1993-11-11 | 1994-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-12 | 1997-11-11 | 1998-05-13 | $7700.00 | Window Closed / Lapsed |