US3777251A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Constant current regulating circuit
Assignee: Motorola Solutions Inc
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Filing: 1972-10-03
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Granted: 1973-12-04
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Expires: 1992-10-03
Abstract
Abstract Circuitry for providing a constant current to a load includes a source of current and a regulating circuit interposed between the current source and the load. The regulating circuit includes a current shunting transistor coupled to the output of the current source and a feedback transistor also coupled to the output of the current source and to the base of the current shunting transistor. A diode connected between the current shunting transistor and the current source is chosen to have a dynamic admittance substantially equal to the transconductance of the current shunting transistor to provide the latter with unity voltage gain. A variation in current output of the source is accommodated by the current shunting transistor so that a substantially constant voltage at the output thereof is maintained. An output circuit including a transistor, coupled to the output of the current shunting transistor and to the load, and controlled by the output voltage, provides a substantially constant current to the load despite current variations from the current source.
Inventors
- 👤 J Cecil
- 👤 W Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 06:36
CPC Classifications
G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/22; G05F3/222; G05F3/227
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
192 words
Circuitry for regulating the output current of a current source to provide a substantially constant current to a load, the current source being connected to a reference potential, the improvement comprising: a. a junction point; b. a P-N semiconductive junction device, connected to the current source, and oriented to pass current to the junction point; c. a current shunting semiconductive device having a first main electrode connected to the junction point, a second main electrode connected to a common reference point, and a control electrode, the dynamic electrical characteristics of the current shunting semiconductor device and the P-N junction semiconductive device being equal for providing the former with unity gain; d. feedback circuit means connected to the connection between the current source and the P-N junction semiconductive device and the control electrode of the current shunting semiconductive device for providing the latter with signals representative of changes in current supplied by the current source for maintaining the junction point at a constant voltage; and e. output circuit means connected to the load and to the junction point, responsive to the voltage at the junction point, for providing constant current to the load.
Claim 2
Dependent Claim
192 words
Circuitry for regulating the output current of a current source to provide a substantially constant current to a load, the current source being connected to a reference potential, the improvement comprising: a. a junction point; b. a P-N semiconductive junction device, connected to the current source, and oriented to pass current to the junction point; c. a current shunting semiconductive device having a first main electrode connected to the junction point, a second main electrode connected to a common reference point, and a control electrode, the dynamic electrical characteristics of the current shunting semiconductor device and the P-N junction semiconductive device being equal for providing the former with unity gain; d. feedback circuit means connected to the connection between the current source and the P-N junction semiconductive device and the control electrode of the current shunting semiconductive device for providing the latter with signals representative of changes in current supplied by the current source for maintaining the junction point at a constant voltage; and e. output circuit means connected to the load and to the junction point, responsive to the voltage at the junction point, for providing constant current to the load.
Claim 3
Dependent Claim
57 words
The circuit of claim 1 wherein the feedback circuit means further comprise a semiconductive device having a first main electrode connected to the reference potential, a control electrode connected to the connection between the current source and the semiconductive junction device, and a second main electrode connected to the control electrode of the current shunting semiconductive device.
Claim 4
Dependent Claim
45 words
The circuit of claim 2 wherein the output circuit means further comprises a semiconductive device having a first maiN electrode connected to the load, a second main electrode electrically coupled to the common reference point and a control electrode electrically connected to the junction point.
Claim 5
Dependent Claim
58 words
The regulating circuitry of claim 1 wherein the current shunting semiconductive device is a transistor, the collector and emitter thereof being the first and second main electrodes and the base being the control electrode, and wherein the P-N junction semiconductive device is a diode whose dynamic admittance is substantially equal to the transconductance of the current shunting transistor.
Claim 6
Dependent Claim
32 words
The regulating circuitry of claim 2 wherein the feedback semiconductive device is a transistor whose collector and emitter are the first and second main electrodes and whose base is the control electrode.
Claim 7
Dependent Claim
33 words
The regulating circuitry of claim 3 wherein the output circuit semiconductive device is a transistor whose collector and emitter are the first and second main electrodes and whose base is the control electrode.
Claim 8
Dependent Claim
32 words
The regulating circuitry of claim 4 wherein the feedback semiconductive device is a transistor whose collector and emitter are the first and second main electrodes and whose base is the control electrode.
Claim 9
Dependent Claim
33 words
The regulating circuitry of claim 5 wherein the output circuit semiconductive device is a transistor whose collector and emitter are the first and second main electrodes and whose base is the control electrode.
Claim 10
Dependent Claim
26 words
Circuitry of the type claimed in claim 8 wherein said constant current source comprises a field effect transistor connected to provide a relatively constant current output.
References Cited (Backward Citations)
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US3303413A
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US3588672A
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US3681623A
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US3629692A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |