US5282107A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Power MOSFET safe operating area current limiting device
Assignee: Power Integrations Inc
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Filing: 1992-09-01
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Granted: 1994-01-25
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Expires: 2012-09-01
Abstract
Abstract An embodiment of the present invention is a switching power supply that includes a full-wave bridge rectifier to rectify incoming AC line voltage, a transformer having a primary winding and two secondary windings and a switched mode power supply chip that includes an integrated high voltage power MOSFET with a low voltage tap in the drift region. The MOSFET controls power switching of the primary winding of the transformer and has a high voltage present during initial power-up. This high voltage is dropped across the JFET part of the MOSFET and supplies a safe operating area protection circuit with a low voltage signal that will shut-off the MOSFET if the current passing through the MOSFET produces a voltage drop at the tap that exceeds a predetermined maximum.
Inventors
- 👤 Balu Balakrishnan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:38
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0822
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
119 words
A switched mode power supply chip, comprising: power switching means for switching a primary winding current of a switched mode power supply transformer on and off, the power switching means comprising a first transistor for limiting the voltage applied to a drain of a second transistor; a low voltage tap connected to said drain of said second transistor such that a sense voltage proportional to a current passing through said first and second transistors is output from the low voltage tap when said first and second transistors are turned on; and comparator means for disabling the power switching means whenever said sense voltage exceeds a predetermined maximum wherein the power switching means is operated in its safe operating area.
Claim 2
Dependent Claim
119 words
A switched mode power supply chip, comprising: power switching means for switching a primary winding current of a switched mode power supply transformer on and off, the power switching means comprising a first transistor for limiting the voltage applied to a drain of a second transistor; a low voltage tap connected to said drain of said second transistor such that a sense voltage proportional to a current passing through said first and second transistors is output from the low voltage tap when said first and second transistors are turned on; and comparator means for disabling the power switching means whenever said sense voltage exceeds a predetermined maximum wherein the power switching means is operated in its safe operating area.
Claim 3
Dependent Claim
36 words
The chip of claim 1, wherein: the power switching means is a MOSFET device and said first transistor is a JFET with a grounded gate and said second transistor is an IGFET with a grounded source.
Claim 4
Dependent Claim
39 words
The chip of claim 1, wherein: the comparator means comprises an inverter with an input switching threshold of approximately 2.5 volts and a flip-flop that is reset by said inverter and that drives a gate of said second transistor.
Claim 5
Dependent Claim
69 words
The chip of claim 1, wherein: the power switching means is a MOSFET device and said first transistor is a JFET with a grounded gate and said second transistor is an IGFET with a grounded source; and the comparator means comprises an inverter with an input switching threshold of approximately 2.5 volts and a flip-flop that is reset by said inverter and that drives a gate of said IGFET.
Claim 6
Dependent Claim
122 words
An integrated circuit (IC) with safe operating area protection, the IC comprising: power switching means for switching a high voltage output current connected to the IC on and off, the power switching means including a first transistor for limiting a voltage applied to a drain of a second transistor; a low voltage tap connected to said drain of said second transistor such that a sense voltage proportional to a current passing through said first and second transistors is output from the low voltage tap when said first and second transistors are turned on; and comparator means for disabling the power switching means whenever said sense voltage exceeds a predetermined maximum wherein the power switching means is operated in its safe operating area.
Claim 7
Dependent Claim
122 words
An integrated circuit (IC) with safe operating area protection, the IC comprising: power switching means for switching a high voltage output current connected to the IC on and off, the power switching means including a first transistor for limiting a voltage applied to a drain of a second transistor; a low voltage tap connected to said drain of said second transistor such that a sense voltage proportional to a current passing through said first and second transistors is output from the low voltage tap when said first and second transistors are turned on; and comparator means for disabling the power switching means whenever said sense voltage exceeds a predetermined maximum wherein the power switching means is operated in its safe operating area.
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) | 1997-01-24 | 1997-07-26 | 1998-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-01-24 | 2001-07-26 | 2002-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-01-24 | 2005-07-26 | 2006-01-25 | $7700.00 | Window Closed / Lapsed |