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Patent US4423457A successfully refreshed from Google Patents.
US4423457A
Expired / Lapsed
US
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Overload protection circuit for a semiconductor switch
Assignee: Siemens AG
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Filing: 1982-01-29
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Granted: 1983-12-27
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Expires: 2002-01-29
Abstract
Abstract An overload protection circuit for a semiconductor switch has a control line which can be shorted, via the collector-emitter path of a transistor, to the ground. The base of the transistor is connected to the output of a comparison stage. One input of the comparison stage is connected via a resistor to the control line, via a diode to the lead of the semiconductor switch facing away from the ground potential, and via a capacitor to ground. A fixed reference voltage is applied to the second input of the comparator stage. In this circuit, a control pulse is shorted as soon as the voltage across the semiconductor switch exceeds a given value because of overcurrent. The short circuit of the addressing pulse is cancelled again as soon as the latter goes back to zero.
Inventors
- 👤 Antonio Brajder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 19:30
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0826
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
165 words
An overload protection circuit for a semiconductor switch, the semiconductor switch having a control input, a connection to ground, and a third lead, the overload protection circuit comprising: a control line coupled to the control input of the semiconductor switch; a transistor having a base and a collector-emitter path coupled between the control line and ground; a comparison stage for detecting an overload, the comparison stage having a first input, a second input and an output, the first input of the comparison stage being coupled via a resistor to the control line of the semiconductor switch, via a diode to the third lead of the semiconductor switch, and via a first capacitor to ground; the second input of the comparison stage being coupled to a reference voltage; and the output of the comparison stage being coupled to the base of the transistor; and a shunt circuit having a second diode coupled across the resistor, the cathode of the second diode coupled to the control line.
Claim 2
Dependent Claim
165 words
An overload protection circuit for a semiconductor switch, the semiconductor switch having a control input, a connection to ground, and a third lead, the overload protection circuit comprising: a control line coupled to the control input of the semiconductor switch; a transistor having a base and a collector-emitter path coupled between the control line and ground; a comparison stage for detecting an overload, the comparison stage having a first input, a second input and an output, the first input of the comparison stage being coupled via a resistor to the control line of the semiconductor switch, via a diode to the third lead of the semiconductor switch, and via a first capacitor to ground; the second input of the comparison stage being coupled to a reference voltage; and the output of the comparison stage being coupled to the base of the transistor; and a shunt circuit having a second diode coupled across the resistor, the cathode of the second diode coupled to the control line.
Claim 3
Dependent Claim
56 words
An overload protection circuit for a semiconductor switch in accordance with claim 1, and further comprising: a second capacitor connected in the shunt circuit in series with the second diode and a second resistor connected in parallel with the second diode, the second capacitor having a capacitance which is larger than that of the first capacitor.
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) | 1986-12-26 | 1987-06-27 | 1987-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-26 | 1991-06-27 | 1991-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-26 | 1995-06-27 | 1995-12-27 | $7700.00 | Window Closed / Lapsed |