US4779037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual input low dropout voltage regulator
Assignee: National Semiconductor Corp
•
Filing: 1987-11-17
•
Granted: 1988-10-18
•
Expires: 2007-11-17
Abstract
Abstract A low dropout voltage regulator with a switched redundant input, which has low dropout voltage before, during, and after a switch to the redundant input. In a preferred embodiment, the inventive voltage regulator includes two transistors that are controlled by the output of an error amplifier, and redundant input voltage sources. A first one of the transistors conducts when a first input voltage is greater than a second input voltage. The other transistor conducts when the second input voltage exceeds the first input voltage. When both input voltages are have substantially equal magnitude, both transistors conduct. In a preferred embodiment, one input voltage is supplied by a battery, and the other is supplied by a storage capacitor charged by the battery. When the battery fails, the storage capacitor will discharge, thus serving as a time-varying redundant voltage source in the event of battery failure.
Inventors
- 👤 James J. LoCascio
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:34
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/56; G05F1/565; G05F1/569; H; H02; H02J; H02J9/00; H02J9/04; H02J9/06; H02J9/061
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
110 words
A low dropout, switched redundant input, voltage regulator, including: (a) an output terminal for providing an output voltage; (b) a reference voltage source for providing a reference voltage signal: (c) a first variable current means for generating a first current output signal whose magnitude varies in response to a first input voltage signal and a control signal; (d) a second variable current means for generating a second current output signal whose magnitude varies in reponse to a second input voltage signal and said control signal; (e) means for generating said control signal by comparing said reference voltage signal with the first current output signal and the second current output signal.
Claim 2
Dependent Claim
110 words
A low dropout, switched redundant input, voltage regulator, including: (a) an output terminal for providing an output voltage; (b) a reference voltage source for providing a reference voltage signal: (c) a first variable current means for generating a first current output signal whose magnitude varies in response to a first input voltage signal and a control signal; (d) a second variable current means for generating a second current output signal whose magnitude varies in reponse to a second input voltage signal and said control signal; (e) means for generating said control signal by comparing said reference voltage signal with the first current output signal and the second current output signal.
Claim 3
Dependent Claim
65 words
The apparatus of claim 1, wherein the first variable current means includes a first transistor including a first emitter which receives the first input voltage signal and a first base which receives the control signal, and wherein the second variable current means includes a second transistor including second emitter which receives the second input voltage signal and a second base which receives the control signal.
Claim 4
Dependent Claim
50 words
The apparatus of claim 2, wherein element (e) is an error emplifier including first input terminal for receiving the reference voltage signal and a second input terminal for receiving a feedback signal whose magnitude varies in response to both the first current output signal and the second current output signal.
Claim 5
Dependent Claim
62 words
The apparatus for claim 1, also including: (f) a battery for supplying the first input voltage signal; (g) a storage capacitor for supplying the second input voltage signal; and (h) means for preventing current from flowing from the storage capacitor to the first variable current means when the magnitude of the second voltage signal exceeds the magnitude of the first voltage signal.
Claim 6
Dependent Claim
56 words
The apparatus of claim 1, wherein the magnitude of the control signal varies in response to a bias current at a bias terminal of element (e), and also including: (j) means for generating the bias current in such a manner that the amplitude of the bias current is proportional to the amplitude of the control signal.
Claim 7
Dependent Claim
25 words
The apparatus of claim 5, wherein element (j) includes current mirroring means connected between elements (c) and (d) and the bias terminal of element (e).
Claim 8
Dependent Claim
158 words
A low dropout, switched redundant input, voltage regulator, including: an output terminal for providing an output voltage; a first input voltage terminal for providing a first input voltage signal; a second input voltage terminal for providing a second input voltage signal; a reference voltage source; first variable current means connected between the first input voltage terminal and the output terminal and capable of producing a first output current signal whose magnitude varies in response to a control signal; second variable current means connected between the second input voltage terminal and the output terminal and capable of producing second output current signal whose magnitude varies in response to the control signal; and control means for controlling the first output current signal and the second output current signal by generating the control signal in such a manner that magnitude of the control signal is proportional to the difference between the reference voltage and a signal proportional to the output voltage.
Claim 9
Dependent Claim
158 words
A low dropout, switched redundant input, voltage regulator, including: an output terminal for providing an output voltage; a first input voltage terminal for providing a first input voltage signal; a second input voltage terminal for providing a second input voltage signal; a reference voltage source; first variable current means connected between the first input voltage terminal and the output terminal and capable of producing a first output current signal whose magnitude varies in response to a control signal; second variable current means connected between the second input voltage terminal and the output terminal and capable of producing second output current signal whose magnitude varies in response to the control signal; and control means for controlling the first output current signal and the second output current signal by generating the control signal in such a manner that magnitude of the control signal is proportional to the difference between the reference voltage and a signal proportional to the output voltage.
Claim 10
Dependent Claim
55 words
The apparatus of claim 7, wherein the magnitude of the control signal varies in response to a bias current at a bias terminal of the control means, and including: means for generating the bias current in such a manner that the amplitude of the bias current is proportional to the amplitude of the control signal.
Claim 11
Dependent Claim
41 words
The apparatus of claim 7, wherein the first variable current means includes a first transistor electrically connected with the first input voltage terminal, and the second variable current means includes a second transistor electrically connected with the second input voltage terminal.
Claim 12
Dependent Claim
54 words
The apparatus of claim 9, wherein the first transistor includes a first emitter connected to the first input voltage terminal and a first base which receives the control signal, and wherein the second transistor includes a first emitter connected to the second input voltage terminal and a second base which receives the control signal.
Claim 13
Dependent Claim
20 words
The apparatus of claim 10, wherein the second transistor includes a collector from which the second output current signal emerges.
Claim 14
Dependent Claim
27 words
The apparatus of claim 7, also including: a battery for supplying the first input voltage signal; and a storage capacitor for supplying the second input voltage signal.
Claim 15
Dependent Claim
18 words
The apparatus of claim 12, also including a charge circuit for charging the storage capacitor from the battery.
Claim 16
Dependent Claim
27 words
The apparatus of claim 13, wherein the charge circuit includes a diode which prevents significant current flow from the storage capacitor to the first variable current means.
References Cited (Backward Citations)
US4209710A
Cited
US4384350A
Cited
US4354118A
Cited
US4543522A
Cited
US4645943A
Cited
US4716354A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-18 | 1992-04-18 | 1992-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-18 | 1996-04-18 | 1996-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-18 | 2000-04-18 | 2000-10-18 | $7700.00 | Window Closed / Lapsed |