US5892389A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and circuit for current limiting of DC-DC regulators
Assignee: Semiconductor Components Industries LLC
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Filing: 1997-06-03
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Granted: 1999-04-06
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Expires: 2017-06-03
Abstract
Abstract A method and circuit (10) for limiting current (I COIL ) in a load (16). The current limiting circuit (10) includes a sensing circuit (12) having a current indicator output terminal (20) connected to an inverting input of a comparator (11). A reference voltage node (24) of a reference voltage generator (13) is connected to the non-inverting input of the comparator (11). The comparator (11) generates an output signal in accordance with the current flowing in the load (16). If an overcurrent condition exists, the signal from the comparator (11) disables a control circuit (14) which turns off the sensing circuit (12). With the control circuit (14) disabled and sensing circuit (14) off, the current (I COIL ) is prevented from flowing through the load (16).
Inventors
- 👤 Nelson C. Lai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:29
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/32; H01; H01H; H01H47/00; H01H47/22; H01H47/32; H01H47/325; H03; H03K; H03K17/00; H03K17/08; H03K17/082; H03K17/0822; H01F; H01F7/00; H01F7/06; H01F7/08; H01F7/18; H01F7/1844; H02M1/0003; H02M1/0009; H02M3/00; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155; H02M3/1555; H02M3/156
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
209 words
A current limiting circuit, comprising: a first transistor having a control electrode, first and second current carrying electrodes, and an on-resistance; a second transistor having a control electrode, first and second current carrying electrodes and an on-resistance, wherein the first current carrying electrode of the second transistor is coupled to the first current carrying electrode of the first transistor, and the control electrode of the second transistor is coupled to the control electrode of the first transistor; a third transistor having a control electrode coupled to the control electrodes of the first and second transistors, a first current carrying electrode coupled to the second current carrying electrode of the second transistor, and an on-resistance; a comparator having first and second inputs and an output, wherein the first input is coupled to the first current carrying electrode of the third transistor and the output is coupled to the control electrode of the first transistor; a reference transistor having a control electrode, first and second current carrying electrodes, and an on-resistance, wherein the first current carrying electrode is coupled to the second input of the comparator; and a current source having first and second terminals, wherein the second terminal is coupled to the first current carrying electrode of the reference transistor.
Claim 2
Dependent Claim
209 words
A current limiting circuit, comprising: a first transistor having a control electrode, first and second current carrying electrodes, and an on-resistance; a second transistor having a control electrode, first and second current carrying electrodes and an on-resistance, wherein the first current carrying electrode of the second transistor is coupled to the first current carrying electrode of the first transistor, and the control electrode of the second transistor is coupled to the control electrode of the first transistor; a third transistor having a control electrode coupled to the control electrodes of the first and second transistors, a first current carrying electrode coupled to the second current carrying electrode of the second transistor, and an on-resistance; a comparator having first and second inputs and an output, wherein the first input is coupled to the first current carrying electrode of the third transistor and the output is coupled to the control electrode of the first transistor; a reference transistor having a control electrode, first and second current carrying electrodes, and an on-resistance, wherein the first current carrying electrode is coupled to the second input of the comparator; and a current source having first and second terminals, wherein the second terminal is coupled to the first current carrying electrode of the reference transistor.
Claim 3
Dependent Claim
18 words
The current limiting circuit of claim 1, wherein the current source is a zero temperature coefficient current source.
Claim 4
Dependent Claim
28 words
The current limiting circuit of claim 1, wherein the second current carrying electrodes of the first, third, and reference transistors are coupled to a first power supply terminal.
Claim 5
Dependent Claim
31 words
The current limiting circuit of claim 3, wherein the control electrode of the reference transistor and the first terminal of the current source are coupled to a second power supply terminal.
Claim 6
Dependent Claim
33 words
The current limiting circuit of claim 1, wherein a ratio of the on-resistance of the first transistor to a sum of the on-resistances of the second and third transistors is at least 1:80.
Claim 7
Dependent Claim
25 words
The current limiting circuit of claim 5, wherein the on-resistance of the third transistor to the on-resistance of the reference transistor is at least 1:400.
Claim 8
Dependent Claim
19 words
The current limiting circuit of claim 1, wherein the first, second, third, and reference transistors are field effect transistors.
Claim 9
Dependent Claim
17 words
The current limiting circuit of claim 7, wherein the field effect transistors are N-channel field effect transistors.
Claim 10
Dependent Claim
57 words
The current limiting circuit of claim 1, further including a pulse width modulation control circuit having an input and an output, wherein the input of the pulse width modulation circuit is coupled to the output of the comparator and the output of the pulse width modulation circuit is coupled to the control electrode of the first transistor.
Claim 11
Dependent Claim
29 words
The current limiting circuit of claim 1, further including a power supply terminal coupled to the first current carrying electrodes of the first and second transistors via an inductor.
Claim 12
Dependent Claim
158 words
An on-chip DC-DC regulator, comprising: means for limiting current, wherein the means for limiting current includes: a first transistor having a control electrode and first and second current carrying electrodes; a second transistor having a control electrode and first and second current carrying electrodes, wherein the first current carrying electrodes of the first and second transistors are commonly coupled; and a third transistor having a control electrode and first and second current carrying electrodes, wherein the first current carrying electrode of the third transistor is coupled to the second current carrying electrode of the second transistor, and the control electrodes of the first, second, and third transistors are commonly connected; a comparator having first and second inputs and an output, wherein the first input is coupled to the means for limiting current; a reference voltage generator coupled to the second input of the comparator; and a control circuit coupled between the comparator and the means for limiting current.
Claim 13
Dependent Claim
158 words
An on-chip DC-DC regulator, comprising: means for limiting current, wherein the means for limiting current includes: a first transistor having a control electrode and first and second current carrying electrodes; a second transistor having a control electrode and first and second current carrying electrodes, wherein the first current carrying electrodes of the first and second transistors are commonly coupled; and a third transistor having a control electrode and first and second current carrying electrodes, wherein the first current carrying electrode of the third transistor is coupled to the second current carrying electrode of the second transistor, and the control electrodes of the first, second, and third transistors are commonly connected; a comparator having first and second inputs and an output, wherein the first input is coupled to the means for limiting current; a reference voltage generator coupled to the second input of the comparator; and a control circuit coupled between the comparator and the means for limiting current.
Claim 14
Dependent Claim
71 words
The on-chip DC-DC regulator of claim 11, wherein the reference voltage generator includes: a reference transistor having a control electrode, a first current carrying electrode, and a second current carrying electrode, wherein the first current carrying electrode is coupled to the second input of the comparator; and a current source having first and second terminals, wherein the second terminal is coupled to the first current carrying electrode of the reference transistor.
Claim 15
Dependent Claim
18 words
The on-chip DC-DC regulator of claim 11, wherein the control circuit is a pulse width modulation control circuit.
Claim 16
Dependent Claim
18 words
The on-chip DC-DC regulator of claim 12, wherein the current source is a zero temperature coefficient current source.
Claim 17
Dependent Claim
46 words
The on-chip DC-DC regulator of claim 11, wherein the reference voltage generator includes a reference transistor having a control electrode, a first current carrying electrode, and a second current carrying electrode, wherein the first current carrying electrode is coupled to the second input of the comparator.
Claim 18
Dependent Claim
65 words
The on-chip DC-DC regulator of claim 15, wherein a ratio of an on-resistance of the first transistor to a sum of an on-resistance of the second transistor and an on-resistance of the third transistor is set to a first predetermined ratio and a ratio of the on-resistance of the third transistor to an on-resistance of the reference transistor is set to a second predetermined ratio.
Claim 19
Dependent Claim
21 words
The on-chip DC-DC regulator of claim 16, wherein the first predetermined ratio is 1:100 and the second predetermined ratio is 1:500.
Claim 20
Dependent Claim
24 words
The on-chip DC-DC regulator of claim 11, further including a coil coupled to the first current carrying electrodes of the first and second transistors.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-04-05 | 2002-10-05 | 2003-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-04-05 | 2006-10-05 | 2007-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-04-05 | 2010-10-05 | 2011-04-06 | $7700.00 | Window Closed / Lapsed |