US5465188A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit protection device
Assignee: Littelfuse Inc
•
Filing: 1991-12-12
•
Granted: 1995-11-07
•
Expires: 2011-12-12
Abstract
Abstract A circuit protection arrangement that is intended to be series connected in a line of an electrical circuit comprises a transistor switch 1 that controls the circuit current and has a control input, and a control arrangement that controls the voltage of the control input of the switch. The control arrangement comprises a comparator circuit 3 that compares a fraction of the voltage across the switch 1 with a reference voltage, for example supplied by a Zener diode or bandgap diode, and opens the switch if the fraction is greater than the reference voltage. The comparator circuit is powered by the voltage drop in the line across the switch so that the arrangement can be formed as a two-terminal device that requires no external power source. The arrangement has the advantage that it exhibits a relatively small variation in performance with respect to temperature variations.
Inventors
- 👤 Dennis M. Pryor
- 👤 Michael Challis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:21
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/08; H02; H02H; H02H3/00; H02H3/08; H02H3/087; H02H3/02; H02H3/06; H02H3/07
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
103 words
A circuit protection arrangement that is series connected in a line of an electrical circuit to be protected, which comprises a transistor switch that controls the circuit current and has a control input, and a control arrangement that controls the voltage of the control input and is responsive to an overcurrent through the switch, the control arrangement comprising a comparator circuit that compares a fraction of the voltage across the switch with a reference voltage and opens the switch if the fraction is greater than the reference voltage, the comparator circuit being powered by a voltage drop in the line across the switch.
Claim 2
Dependent Claim
103 words
A circuit protection arrangement that is series connected in a line of an electrical circuit to be protected, which comprises a transistor switch that controls the circuit current and has a control input, and a control arrangement that controls the voltage of the control input and is responsive to an overcurrent through the switch, the control arrangement comprising a comparator circuit that compares a fraction of the voltage across the switch with a reference voltage and opens the switch if the fraction is greater than the reference voltage, the comparator circuit being powered by a voltage drop in the line across the switch.
Claim 3
Dependent Claim
21 words
An arrangement as claimed in claim 1, wherein the switch comprises an enhancement mode MOSFET whose gate provides the control input.
Claim 4
Dependent Claim
19 words
An arrangement as claimed in claim 1, wherein the voltage reference comprises a Zener diode or a bandgap device.
Claim 5
Dependent Claim
36 words
An arrangement as claimed in claim 1, which includes a pulse generator which, when the switch has opened, will send one or more pulses to the switch to close or to attempt to close the switch.
Claim 6
Dependent Claim
22 words
An arrangement as claimed in claim 4, wherein the pulse generator comprises a divider whose input is supplied by an astable oscillator.
Claim 7
Dependent Claim
26 words
An arrangement as claimed in claim 4, wherein the or each pulse generated by the pulse generator has a length of not more than 250 ms.
Claim 8
Dependent Claim
20 words
An arrangement as claimed in claim 4, wherein the pulse generator will generate pulses to a predetermined finite maximum number.
Claim 9
Dependent Claim
18 words
An arrangement as claimed in claim 1, which includes no resistive components in series with the transistor switch.
Claim 10
Dependent Claim
19 words
An arrangement as claimed in claim 2, wherein the voltage reference comprises a Zener diode or a bandgap device.
Claim 11
Dependent Claim
36 words
An arrangement as claimed in claim 2, which includes a pulse generator which, when the switch has opened, will send one or more pulses to the switch to close or to attempt to close the switch.
Claim 12
Dependent Claim
36 words
An arrangement as claimed in claim 3, which includes a pulse generator which, when the switch has opened, will send one or more pulses to the switch to close or to attempt to close the switch.
Claim 13
Dependent Claim
36 words
An arrangement as claimed in claim 9, which includes a pulse generator which, when the switch has opened, will send one or more pulses to the switch to close or to attempt to close the switch.
Claim 14
Dependent Claim
26 words
An arrangement as claimed in claim 5, wherein the or each pulse generated by the pulse generator has a length of not more than 250 ms.
Claim 15
Dependent Claim
20 words
An arrangement as claimed in claim 5, wherein the pulse generator will generate pulses to a predetermined finite maximum number.
Claim 16
Dependent Claim
20 words
An arrangement as claimed in claim 6, wherein the pulse generator will generate pulses to a predetermined finite maximum number.
Claim 17
Dependent Claim
18 words
An arrangement as claimed in claim 4, wherein the pulse generator will generate pulses for a predetermined time.
Claim 18
Dependent Claim
18 words
An arrangement as claimed in claim 5, wherein the pulse generator will generate pulses for a predetermined time.
Claim 19
Dependent Claim
18 words
An arrangement as claimed in claim 6, wherein the pulse generator will generate pulses for a predetermined time.
Claim 20
Dependent Claim
23 words
An arrangement as claimed in claim 1, wherein the reference voltage is obtained from the voltage drop in the line across the switch.
References Cited (Backward Citations)
DE1233475B
Cited
GB1467055A
Cited
US3801872A
Cited
GB1481458A
Cited
DE2431167A1
Cited
DE2440947A1
Cited
US4021701A
Cited
US4202023A
Cited
US4241372A
Cited
US4423457A
Cited
US4438473A
Cited
US4513343A
Cited
US4604674A
Cited
DE3433538A1
Cited
WO1986003079A1
Cited
US4771357A
Cited
DE3725390A1
Cited
US4809122A
Cited
US4937697A
Cited
WO1991007403A1
Cited
WO1991007402A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-11-06 | 1999-05-08 | 1999-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-06 | 2003-05-08 | 2003-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-06 | 2007-05-08 | 2007-11-07 | $7700.00 | Window Closed / Lapsed |