US4779027A
Expired / Lapsed
US
⏱️ 0.0 years remaining
DC to DC converter with overvoltage protection circuit
Assignee: Tomar Electronics Inc
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Filing: 1987-04-24
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Granted: 1988-10-18
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Expires: 2007-04-24
Abstract
Abstract An overvoltage protection circuit limits the output voltage of a DC to DC converter to a maximum desired output voltage. An output voltage sensing circuit includes a semiconductor device such as a sidac having a normal resistive region of operation as well as a negative resistance region of operation which begins at a breakover voltage and extends into a foldback region. One terminal of the sidac is coupled to sense the converter output voltage while the second terminal opposite end of the sidac is coupled to a biasing device in the form of a resistor which generates an overvoltage signal when the sidac conducts current. The overvoltage signal from the biasing resistor is coupled to a converter switching transistor disabling circuit which reduces the converter output voltage to a level below the maximum desired output voltage in response to the overvoltage signal.
Inventors
- 👤 Scott T. Sikora
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:02
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
302 words
An overvoltage protection circuit for limiting the output voltage of a power supply energizing a capacitive load to a maximum desired output voltage, comprising: a. output voltage sensing means including i. semiconductor means having first and second terminals coupled to sense an applied voltage and including a resistive region of operation beginning at a breakover voltage and extending into a foldback region, said semiconductor means conducting a significant level of current while operating in the negative resistance foldback region for a defined time interval beginning as the applied voltage reaches the breakover voltage and ending as a lower operating limit voltage within the foldback region is reached where said semiconductor means transitions out of the negative resistance foldback region and resumes operation in the resisting region; ii. voltage scaling means for coupling the first terminal of said semiconductor means to sense the output voltage of said power supply and for scaling the output voltage such that the power supply voltage transmitted to the first terminal of said semiconductor means equals the breakover voltage of said semiconductor means when the output voltage of said power supply reaches the maximum desired output voltage; iii. biasing means having an input terminal coupled to the second terminal of said semiconductor means and an output terminal, said biasing means generating an overvoltage signal when said semiconductor means conducts current while operating in the foldback region and preventing operation of said semiconductor means in the negative resistance region beyond the foldback region; and b. power supply disabling means coupled to the second terminal of said biasing means and to said power supply and being responsive to the overvoltage signal from said biasing means for decreasing the power supply output voltage to a level below the maximum desired output voltage when said semiconductor means operates within the foldback region.
Claim 2
Dependent Claim
302 words
An overvoltage protection circuit for limiting the output voltage of a power supply energizing a capacitive load to a maximum desired output voltage, comprising: a. output voltage sensing means including i. semiconductor means having first and second terminals coupled to sense an applied voltage and including a resistive region of operation beginning at a breakover voltage and extending into a foldback region, said semiconductor means conducting a significant level of current while operating in the negative resistance foldback region for a defined time interval beginning as the applied voltage reaches the breakover voltage and ending as a lower operating limit voltage within the foldback region is reached where said semiconductor means transitions out of the negative resistance foldback region and resumes operation in the resisting region; ii. voltage scaling means for coupling the first terminal of said semiconductor means to sense the output voltage of said power supply and for scaling the output voltage such that the power supply voltage transmitted to the first terminal of said semiconductor means equals the breakover voltage of said semiconductor means when the output voltage of said power supply reaches the maximum desired output voltage; iii. biasing means having an input terminal coupled to the second terminal of said semiconductor means and an output terminal, said biasing means generating an overvoltage signal when said semiconductor means conducts current while operating in the foldback region and preventing operation of said semiconductor means in the negative resistance region beyond the foldback region; and b. power supply disabling means coupled to the second terminal of said biasing means and to said power supply and being responsive to the overvoltage signal from said biasing means for decreasing the power supply output voltage to a level below the maximum desired output voltage when said semiconductor means operates within the foldback region.
Claim 3
Dependent Claim
38 words
The overvoltage protection circuit of claim 1 wherein said output voltage sensing means continues to generate the overvoltage signal until the power supply output voltage has been decreased to a predetermined level below the maximum desired output voltage.
Claim 4
Dependent Claim
36 words
The overvoltage protection circuit of claim 2 wherein said biasing means discontinues generation of the overvoltage signal as said semiconductor means transitions from operation in the negative resistance foldback region to operation in the resistive region.
Claim 5
Dependent Claim
14 words
The overvoltage protection circuit of claim 3 wherein said semiconductor means includes a sidac.
Claim 6
Dependent Claim
14 words
The overvoltage protection circuit of claim 3 wherien said semiconductor means includes a diac.
Claim 7
Dependent Claim
16 words
The overvoltage protection circuit of claim 3 wherein said semiconductor means includes a silicon bilateral switch.
Claim 8
Dependent Claim
14 words
The overvoltage protection circuit of claim 4 wherein said biasing means inlcudes a resistor.
Claim 9
Dependent Claim
47 words
The overvoltage protection circuit of claim 3 wherein said power supply further includes a switching transistor operating in response to a base drive current and wherein said power supply disabling means shunts the base drive current away from said switching transistor in response to the overvoltage signal.
Claim 10
Dependent Claim
14 words
The overvoltage protection circuit of claim 8 wherein said semiconductor means includes a sidac.
Claim 11
Dependent Claim
35 words
The overvoltage protection circuit of cliam 9 said sidac includes first and second terminals and wherein said voltage scaling means couples the first terminal of said sidac to directly sense the power supply output voltage.
Claim 12
Dependent Claim
35 words
The overvoltage protection circuit of cliam 9 said sidac includes first and second terminals and wherein said voltage scaling means couples the first terminal of said sidac to directly sense the power supply output voltage.
Claim 13
Dependent Claim
19 words
The overvoltage protection circuit of cliam 8 wherein said semiconductor means includes first and second sidacs coupled in series.
Claim 14
Dependent Claim
19 words
The overvoltage protection circuit of cliam 8 wherein said semiconductor means includes first and second sidacs coupled in series.
Claim 15
Dependent Claim
32 words
The overvoltage protection circuit of claim 4 wherein said voltage scaling means includes a voltage conductor for couplng the first terminal of said sidac to directly sense the power supply output voltage.
Claim 16
Dependent Claim
61 words
The overvoltage protection circuit of claim 1 wherein said power supply includes: a. a coupled inductor including a primary winding and a feedback winding; and b. a switching transistor having base, collector and emitter terminals and being coupled in series with said primary winding for switching between conductive and non-conductive states to control the flow of current through said primary winding.
Claim 17
Dependent Claim
46 words
The overvoltage protection circuit of claim 13 wherein said disabling means includes means for switching the base terminal of said switching transistor to ground in response to the overvoltage signal to thereby switch said switching transistor out of the conductive state and into the non-conductive state.
Claim 18
Dependent Claim
51 words
The overvoltage protection circuit of claim 14 wherein said disabling means further includes means for shunting current away from the base terminal of said switching transistor when the primary winding current reaches a predetermined valve to thereby switch said switching transistor out of the conductive state and into the non-conductive state.
Claim 19
Dependent Claim
31 words
The overvoltage protection circuit of claim 14 wherein said capacitive load receives energy stored in said inductor after said switching transistor is switched into the non-conductive state by said shunting means.
Claim 20
Dependent Claim
14 words
The overvoltage protection circuit of claim 16 wherein said semiconductor means includes a sidac.
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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) | 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 |