US4023111A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Current limiting driver circuit
Assignee: National Semiconductor Corp
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Filing: 1976-06-03
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Granted: 1977-05-10
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Expires: 1996-06-03
Abstract
Abstract A driver circuit in which the output current is limited to a particular value. A very low value resistance in the output stage senses the current and modulates the conduction to a diode-amplifier combination. The combination employs ratioed emitter areas and currents and can respond to potentials at P-N junction contact potential level. The circuit has a dynamic voltage range that extends to within almost the emitter-collector saturation of a single transistor of zero.
Inventors
- 👤 Helge H. Mortensen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:18
CPC Classifications
H; H03; H03G; H03G11/00; H03G11/002; H03F; H03F1/00; H03F1/52
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
220 words
An amplifier circuit having a limited and well defined output current and a large dynamic output voltage range comprising: an output stage including output transistor means having emitter, base and collector terminals, means for coupling said collector terminal to a load element whereby said load element may be energized in combination with a power supply from said output stage, current sensing resistor means coupled to said emitter whereby said current sensing resistor means develops a potential proportional to the current in said load element, a feedback stage including a common emitter connected transistor having a base terminal and collector terminal, said collector terminal being coupled to said output stage base terminal and said base terminal coupled by means of a forward biased diode to said output stage emitter terminal and said current sensing resistor, and a driver stage including dual collector common emitter connected transistor means having a base terminal and two collector terminals, said base terminal being coupled to comprise the input of said amplifier, one of said collector terminals being coupled to said base terminal of said output transistor and the collector terminal of said feedback stage transistor, and the other of said collector terminals being coupled to the base of terminal of said feedback stage transistors whereby said output current is sharply limited at a predetermined value.
Claim 2
Dependent Claim
220 words
An amplifier circuit having a limited and well defined output current and a large dynamic output voltage range comprising: an output stage including output transistor means having emitter, base and collector terminals, means for coupling said collector terminal to a load element whereby said load element may be energized in combination with a power supply from said output stage, current sensing resistor means coupled to said emitter whereby said current sensing resistor means develops a potential proportional to the current in said load element, a feedback stage including a common emitter connected transistor having a base terminal and collector terminal, said collector terminal being coupled to said output stage base terminal and said base terminal coupled by means of a forward biased diode to said output stage emitter terminal and said current sensing resistor, and a driver stage including dual collector common emitter connected transistor means having a base terminal and two collector terminals, said base terminal being coupled to comprise the input of said amplifier, one of said collector terminals being coupled to said base terminal of said output transistor and the collector terminal of said feedback stage transistor, and the other of said collector terminals being coupled to the base of terminal of said feedback stage transistors whereby said output current is sharply limited at a predetermined value.
Claim 3
Dependent Claim
66 words
The amplifier of claim 1 wherein the collectors of said driver transistor and the emitter areas of said diode and said feedback stage transistor are scaled to that when the ratio of the currents in said feedback transistor collector and said diode is multiplied by the ratio of the areas of said emitters of said feedback transistor and said diode the result is greater than unity.
Claim 4
Dependent Claim
22 words
The amplifier of claim 2 wherein the emitter of said diode is made greater than the area of said feedback transistor emitter.
Claim 5
Dependent Claim
21 words
The amplifier of claim 2 wherein the current through said diode is made smaller than the current through said feedback transistor.
Claim 6
Dependent Claim
38 words
The amplifier of claim 2 wherein the area of said diode emitter is greater than the area of said feedback transistor emitter and the current through said diode is made smaller than the current through said feedback transistor.
References Cited (Backward Citations)
US2847519A
Cited
US3668545A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-09 | 1980-11-08 | 1981-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-09 | 1984-11-08 | 1985-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-09 | 1988-11-08 | 1989-05-10 | $7700.00 | Window Closed / Lapsed |