US4047233A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Short circuit protection circuit
Assignee: Lear Corp EEDS and Interiors
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Filing: 1976-04-14
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Granted: 1977-09-06
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Expires: 1996-04-14
Abstract
Abstract In a circuit of the type in which a command signal actuates a semiconductor switch which, in turn, actuates a load device and in which a clock signal is available, a protection circuit for protecting the semiconductor switch located in series with the load from excessive current in the event the load device is short circuited. The protection circuit includes a sensing circuit for sensing the voltage level at a point intermediate the semiconductor switch and the load. The protection circuit interfaces between the command signal and the clock signal in such a manner that the semiconductor switch is repeatedly momentarily energized if the load is shorted and a command signal is present.
Inventors
- 👤 Robert G. Yorks
- 👤 David W. Junker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:13
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0826; H02; H02H; H02H3/00; H02H3/02; H02H3/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
213 words
In a switching circuit for controlling the application of power to a load including a semiconductor switch in series with said load connected across a source of power, means for providing a clock signal switching between first and second states, means for providing a command signal switching from a first state to a second state when it is desired to energize said load, a protection circuit for protecting said semiconductor switch in the event said load is short circuited, comprising: sensing circuit means for sensing the voltage across said load and for providing an output signal indicative of whether or not said load is shorted; and circuit means responsive to the output signal of said sensing circuit, said command signal and said clock signal for actuating said semiconductor switch when said command signal switches from said first state to said second state or shortly thereafter, said circuit means thereafter maintaining said semiconductor switch in said actuated state as long as said command signal remains in said second state and the output of said sensing circuit means indicates said load is not shorted, said circuit means momentarily energizing said semiconductor switch when said command signal is in said second state and the output of said sensing circuit means indicates said load is short circuited.
Claim 2
Dependent Claim
213 words
In a switching circuit for controlling the application of power to a load including a semiconductor switch in series with said load connected across a source of power, means for providing a clock signal switching between first and second states, means for providing a command signal switching from a first state to a second state when it is desired to energize said load, a protection circuit for protecting said semiconductor switch in the event said load is short circuited, comprising: sensing circuit means for sensing the voltage across said load and for providing an output signal indicative of whether or not said load is shorted; and circuit means responsive to the output signal of said sensing circuit, said command signal and said clock signal for actuating said semiconductor switch when said command signal switches from said first state to said second state or shortly thereafter, said circuit means thereafter maintaining said semiconductor switch in said actuated state as long as said command signal remains in said second state and the output of said sensing circuit means indicates said load is not shorted, said circuit means momentarily energizing said semiconductor switch when said command signal is in said second state and the output of said sensing circuit means indicates said load is short circuited.
Claim 3
Dependent Claim
110 words
The protection circuit as claimed in claim 1, wherein said circuit means comprises: first logic circuit means responsive to said clock signal and the output signal of said sensing circuit means for providing a high output signal when the output of sensing circuit is high or when clock signal is high; second logic circuit means responsive to the output signal of first logic circuit means and said command signal for providing a high output signal when first logic circuit means has a high output signal and said command signal is high and circuit means for energizing said electronic switch when the output signal from second logic circuit means is high.
Claim 4
Dependent Claim
17 words
A protection circuit as claimed in claim 1, wherein said sensing circuit responds to predetermined voltage threshold.
Claim 5
Dependent Claim
26 words
A protection circuit as claimed in claim 1, wherein said sensing circuit includes time delay means for delaying the application of continuous power to said load.
Claim 6
Dependent Claim
37 words
A protection circuit as claimed in claim 1, wherein the pulse duration and the pulse repetition rate of said clock signal is selected so that the power dissipation of the output switching device remains within safe limits.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-05 | 1981-03-07 | 1981-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-05 | 1985-03-07 | 1985-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-05 | 1989-03-07 | 1989-09-06 | $7700.00 | Window Closed / Lapsed |