Patent US4405964A successfully refreshed from Google Patents.
US4405964A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Over voltage circuit for a switching regulator power supply
Assignee: Zenith Electronics LLC
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Filing: 1982-03-29
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Granted: 1983-09-20
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Expires: 2002-03-29
Abstract
Abstract A protection circuit for a switching regulator power supply comprises a series-pass transistor having a collector-emitter circuit connected between a source of DC operating potential and the power supply. A bootstrap signal developed by the power supply and having a voltage level greater than the potential of the DC source is fed back to the base of the series-pass transistor for rendering the transistor fully conductive under normal operating conditions and to improve performance under marginally low levels of the DC source. A reverse biased diode is connected between the base of the series-pass transistor and the DC source to limit the transistor's base drive via the feedback path to a safe level. A shunting transistor is responsive to an overvoltage condition of the DC source for reducing the base drive of the series-pass transistor to limit the DC potential supplied to the power supply to a safe level.
Inventors
- 👤 Jonathan L. Woods
- 👤 Leroy A. Sutton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:40
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
177 words
A protection circuit for a switching regulator power supply operable in response to a source of DC potential V b for developing a bootstrap signal having a voltage level greater than V b , said protection circuit comprising: a series-pass transistor having a collector-emitter circuit connected between said source of DC potential and said power supply; means for coupling said bootstrap signal to the base of said series-pass transistor; a shunting transistor having a collector-emitter circuit connected between the base of said series-pass transistor and a point of reference potential; and a voltage divider connected between said source of DC potential and said reference potential for coupling a control voltage to the base of said shunting transistor, said control voltage causing said shunting transistor to be non-conductive for values of V b less than a predetermined threshold value and to be conductive for values V b greater than said predetermined threshold value so as to reduce the base drive of said series-pass transistor for limiting the DC potential supplied to said power supply to a safe level.
Claim 2
Dependent Claim
177 words
A protection circuit for a switching regulator power supply operable in response to a source of DC potential V b for developing a bootstrap signal having a voltage level greater than V b , said protection circuit comprising: a series-pass transistor having a collector-emitter circuit connected between said source of DC potential and said power supply; means for coupling said bootstrap signal to the base of said series-pass transistor; a shunting transistor having a collector-emitter circuit connected between the base of said series-pass transistor and a point of reference potential; and a voltage divider connected between said source of DC potential and said reference potential for coupling a control voltage to the base of said shunting transistor, said control voltage causing said shunting transistor to be non-conductive for values of V b less than a predetermined threshold value and to be conductive for values V b greater than said predetermined threshold value so as to reduce the base drive of said series-pass transistor for limiting the DC potential supplied to said power supply to a safe level.
Claim 3
Dependent Claim
64 words
A protection circuit according to claim 1 wherein the collector and emitter of said series-pass transistor are respectively coupled to said source of DC potential and said power supply and further including a diode connected between the base of said series-pass transistor and said source of DC potential for limiting said bootstrap signal at the base of said series-pass transistor to a safe level.
Claim 4
Dependent Claim
49 words
A protection circuit according to claim 2 wherein said bootstrap signal has a voltage level at least two diode voltage drops greater than V b and wherein said means for coupling comprises at least one rectifying diode and a filter circuit connected to the base of said series-pass transistor.
Claim 5
Dependent Claim
41 words
A protection circuit according to claim 2 wherein said bootstrap signal comprises a regulated output voltage of said power supply and including a power supply start-up resistor connected between said source of DC potential and the base of said series-pass transistor.
Claim 6
Dependent Claim
162 words
A protection circuit for a switching regulator power supply operable in response to a source of DC potential V b for developing a bootstrap signal having a voltage level greater than V b , said protection circuit comprising: a series-pass transistor having a collector connected to said source of DC potential and an emitter connected to said power supply; means for coupling said bootstrap signal to the base of said series-pass transistor; diode means connected between the base of said series-pass transistor and said source of DC potential for limiting the voltage developed at the base of said series-pass transistor to a safe level; means for developing a control signal representative of the voltage of said source of DC potential V b ; and a shunting transistor operable in response to said control signal exceeding a predetermined threshold level for reducing the base drive of said series-pass transistor for limiting the DC potential supplied to said power supply to a safe level.
Claim 7
Dependent Claim
162 words
A protection circuit for a switching regulator power supply operable in response to a source of DC potential V b for developing a bootstrap signal having a voltage level greater than V b , said protection circuit comprising: a series-pass transistor having a collector connected to said source of DC potential and an emitter connected to said power supply; means for coupling said bootstrap signal to the base of said series-pass transistor; diode means connected between the base of said series-pass transistor and said source of DC potential for limiting the voltage developed at the base of said series-pass transistor to a safe level; means for developing a control signal representative of the voltage of said source of DC potential V b ; and a shunting transistor operable in response to said control signal exceeding a predetermined threshold level for reducing the base drive of said series-pass transistor for limiting the DC potential supplied to said power supply to a safe level.
Claim 8
Dependent Claim
53 words
A protection circuit according to claim 5 wherein said control signal developing means comprises a voltage divider connected between said source of DC potential and a point of reference potential and wherein said shunting transistor includes a collector-emitter circuit connected between the base of said series-pass transistor and said point of reference potential.
Claim 9
Dependent Claim
49 words
A protection circuit according to claim 5 wherein said bootstrap signal has a voltage level at least two diode voltage drops greater than V b and wherein said means for coupling comprises at least one rectifying diode and a filter circuit connected to the base of said series-pass transistor.
Claim 10
Dependent Claim
41 words
A protection circuit according to claim 5 wherein said bootstrap signal comprises a regulated output voltage of said power supply and including a power supply start-up resistor connected between said source of DC potential and the base of said series-pass transistor.
Claim 11
Dependent Claim
212 words
A protection circuit for a switching regulator power supply operable in response to a source of DC potential V b for developing a bootstrap signal having a voltage level greater than V b , said protection circuit comprising: a series-pass transistor having a collector connected to said source of DC potential and an emitter connected to said power supply; means for coupling said bootstrap signal to the base of said series-pass transistor; diode means connected between the base of said series-pass transistor and said source of DC potential for limiting the voltage developed at the base of said series-pass transistor to a safe level; a shunting transistor having a collector-emitter circuit connected between the base of said series-pass transistor and a point of reference potential; and a voltage divider connected between said source of DC potential and said reference potential for coupling a control voltage to the base of said shunting transistor, said control voltage causing said shunting transistor to be non-conductive for values of V b less than predetermined threshold value and to be conductive for values of V b greater than said predetermined threshold value so as to reduce the base drive of said series-pass transistor for limiting the DC potential supplied to said power supply to a safe level.
Claim 12
Dependent Claim
212 words
A protection circuit for a switching regulator power supply operable in response to a source of DC potential V b for developing a bootstrap signal having a voltage level greater than V b , said protection circuit comprising: a series-pass transistor having a collector connected to said source of DC potential and an emitter connected to said power supply; means for coupling said bootstrap signal to the base of said series-pass transistor; diode means connected between the base of said series-pass transistor and said source of DC potential for limiting the voltage developed at the base of said series-pass transistor to a safe level; a shunting transistor having a collector-emitter circuit connected between the base of said series-pass transistor and a point of reference potential; and a voltage divider connected between said source of DC potential and said reference potential for coupling a control voltage to the base of said shunting transistor, said control voltage causing said shunting transistor to be non-conductive for values of V b less than predetermined threshold value and to be conductive for values of V b greater than said predetermined threshold value so as to reduce the base drive of said series-pass transistor for limiting the DC potential supplied to said power supply to a safe level.
Claim 13
Dependent Claim
49 words
A protection circuit according to claim 9 wherein said bootstrap signal has a voltage level at least two diode voltage drops greater than V b and wherein said means for coupling comprises at least one rectifying diode and a filter circuit connected to the base of said series-pass transistor.
Claim 14
Dependent Claim
41 words
A protection circuit according to claim 9 wherein said bootstrap signal comprises a regulated output voltage of said power supply and including a power supply start-up resistor connected between said source of DC potential and the base of said series-pass transistor.
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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) | 1986-09-19 | 1987-03-21 | 1987-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-19 | 1991-03-21 | 1991-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-19 | 1995-03-21 | 1995-09-20 | $7700.00 | Window Closed / Lapsed |