US4926109A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low dropout voltage regulator with low common current
Assignee: National Semiconductor Corp
•
Filing: 1989-06-21
•
Granted: 1990-05-15
•
Expires: 2009-06-21
Abstract
Abstract A circuit is shown in which a voltage regulator has an output stage that operates as a Darlington when the input-output differential exceeds a threshold. The circuit automatically switches to a common emitter output and an emitter-follower driver when the differential falls below the threshold. A current limiter prevents excessive common current when the output transistor is saturated.
Inventors
- 👤 Matsuro Koterasawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:12
CPC Classifications
H; H02; H02M; H02M3/00; G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/56
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
147 words
A voltage regulator circuit having a common terminal, an input terminal for receiving an unregulated voltage, and an output terminal for supplying a regulated output voltage, said circuit comprising: output transistor means having a base and having its collector-emitter electrodes connected between said input and output terminals; driver transistor means having a transistor emitter coupled to said base of said output transistor and having collector and base electrodes; control transistor means having a transistor emitter coupled to said base of said driver transistor, a collector returned to said common terminal and a base electrode by which said control transistor means operates as an emitter follower; means, responsive to the potential across said output transistor, for switching the collector of said driver transistor to either said output terminal when said potential is below a predetermined value or to said common terminal when said potential exceeds said predetermined value.
Claim 2
Dependent Claim
147 words
A voltage regulator circuit having a common terminal, an input terminal for receiving an unregulated voltage, and an output terminal for supplying a regulated output voltage, said circuit comprising: output transistor means having a base and having its collector-emitter electrodes connected between said input and output terminals; driver transistor means having a transistor emitter coupled to said base of said output transistor and having collector and base electrodes; control transistor means having a transistor emitter coupled to said base of said driver transistor, a collector returned to said common terminal and a base electrode by which said control transistor means operates as an emitter follower; means, responsive to the potential across said output transistor, for switching the collector of said driver transistor to either said output terminal when said potential is below a predetermined value or to said common terminal when said potential exceeds said predetermined value.
Claim 3
Dependent Claim
53 words
The circuit of claim 1 wherein said collector of said driver transistor is coupled by means of a first diode to said output terminal or to said common terminal by means of a controlled current path wherein said means for switching controls the conduction in said first diode and said controlled current path.
Claim 4
Dependent Claim
45 words
The circuit of claim 2 wherein said means for switching comprise second and third diodes commonly coupled via a constant current path to said input terminal and individually coupled to said collector of said driver transistor and to the input of said controlled current path.
Claim 5
Dependent Claim
68 words
The circuit of claim 1 further comprising a differential amplifier having an output coupled to said base of control transistor means, an inverting input coupled to a source of reference potential and a non-inverting input coupled to the tap on a voltage divider coupled between said output and said common terminals whereby the voltage at said output terminal is determined to a first order by said voltage divider.
Claim 6
Dependent Claim
75 words
The circuit of claim 4 further comprising limiting transistor means having a transistor base coupled to said base of said driver transistor, a collector coupled to said base of said control transistor means and an emitter coupled by way of a fourth diode to said output terminal whereby, when said output transistor goes into saturation, said limiting transistor means conducts and pulls the base of said control transistor towards the collector of said output transistor.
References Cited (Backward Citations)
US3261980A
Cited
US3414802A
Cited
US3541425A
Cited
US4042886A
Cited
US4441070A
Cited
US4613809A
Cited
US4792747A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-14 | 1993-11-13 | 1994-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-14 | 1997-11-13 | 1998-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-14 | 2001-11-13 | 2002-05-15 | $7700.00 | Window Closed / Lapsed |