US4914540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overvoltage-protective device
Assignee: Mitsubishi Electric Corp
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Filing: 1988-01-26
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Granted: 1990-04-03
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Expires: 2008-01-26
Abstract
Abstract Voltage-dividing resistors, being connected in parallel to a switching element to be protected, create control voltage which is responsive to voltage applied to the switching element, to supply the same to a gate of a field effect transistor. The field effect transistor is connected in parallel to the switching element, to conduct when the control voltage exceeds a threshold value for passing overvoltage absorbing current, while causing high-frequency shorting across the switching element by its parasitic capacitance.
Inventors
- 👤 Mituharu Tabata
- 👤 Gourab Majumdar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:54
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H03K17/081; H03K17/0814; H03K17/08142; H03K17/08148
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
161 words
An overvoltage-protective device for protecting a device to be protected, being applied with a signal of an arbitrary frequency, against overvoltage, said overvoltage-protective device comprising: means for providing a control signal of voltage value responsive to that of said signal applied to said device to be protected, said means for providing said control signal including voltage-dividing resistors of relatively high resistance values connected in parallel to said device to be protected; and an enhancement field effect transistor which is connected in parallel to said device to be protected, said transistor having a control electrode applied with said control signal to conduct when said voltage value of said control signal is in excess of prescribed value for passing overvoltage absorbing current and having parasitic capacitance so that a signal component of a frequency sufficiently higher than said arbitrary frequency is bypassed through said transistor; wherein said device to be protected includes a switching element which performs switching operation at said arbitrary frequency.
Claim 2
Dependent Claim
161 words
An overvoltage-protective device for protecting a device to be protected, being applied with a signal of an arbitrary frequency, against overvoltage, said overvoltage-protective device comprising: means for providing a control signal of voltage value responsive to that of said signal applied to said device to be protected, said means for providing said control signal including voltage-dividing resistors of relatively high resistance values connected in parallel to said device to be protected; and an enhancement field effect transistor which is connected in parallel to said device to be protected, said transistor having a control electrode applied with said control signal to conduct when said voltage value of said control signal is in excess of prescribed value for passing overvoltage absorbing current and having parasitic capacitance so that a signal component of a frequency sufficiently higher than said arbitrary frequency is bypassed through said transistor; wherein said device to be protected includes a switching element which performs switching operation at said arbitrary frequency.
Claim 3
Dependent Claim
148 words
An overvoltage-protective device for protecting a switching element against overvoltage, said overvoltage-protective device comprising: means for providing a control signal of voltage value responsive to that of a signal applied to said switching element, said means for providing said control signal including voltage-dividing resistors of relatively high resistance values connected in parallel to said switching element; and an enhancement field effect transistor which is connected in parallel to said switching element, said transistor having a control electrode applied with said control signal to conduct when said voltage value of said control signal is in excess of prescribed value for passing overvoltage absorbing current and having parasitic capacitance so that a signal component of a relatively high frequency is bypassed through the transistor; wherein said switching element is switched at a frequency lower than that of said signal component bypassed by said parasitic capacitance of said field effect transistor.
Claim 4
Dependent Claim
148 words
An overvoltage-protective device for protecting a switching element against overvoltage, said overvoltage-protective device comprising: means for providing a control signal of voltage value responsive to that of a signal applied to said switching element, said means for providing said control signal including voltage-dividing resistors of relatively high resistance values connected in parallel to said switching element; and an enhancement field effect transistor which is connected in parallel to said switching element, said transistor having a control electrode applied with said control signal to conduct when said voltage value of said control signal is in excess of prescribed value for passing overvoltage absorbing current and having parasitic capacitance so that a signal component of a relatively high frequency is bypassed through the transistor; wherein said switching element is switched at a frequency lower than that of said signal component bypassed by said parasitic capacitance of said field effect transistor.
Claim 5
Dependent Claim
78 words
An overvoltage-protective device for protecting a device to be protected, comprising: two input terminals connected to terminals of said device to be protected; an enhancement field effect transistor having three terminals, two of said three terminals being connected to said two input terminals; two voltage dividing resistors, each having one terminal in common and one terminal connected to one of said input terminals; said terminal in common being connected to the third terminal of said field effect transistor.
Claim 6
Dependent Claim
78 words
An overvoltage-protective device for protecting a device to be protected, comprising: two input terminals connected to terminals of said device to be protected; an enhancement field effect transistor having three terminals, two of said three terminals being connected to said two input terminals; two voltage dividing resistors, each having one terminal in common and one terminal connected to one of said input terminals; said terminal in common being connected to the third terminal of said field effect transistor.
References Cited (Backward Citations)
DE2148445A1
Cited
US4323942A
Cited
DE3145592A1
Cited
US4449158A
Cited
US4546401A
Cited
US4630162A
Cited
US4658320A
Cited
DE3537419A1
Cited
US4745511A
Cited
US4739437A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-02 | 1993-10-02 | 1994-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-02 | 1997-10-02 | 1998-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-02 | 2001-10-02 | 2002-04-03 | $7700.00 | Window Closed / Lapsed |