Circuit protection arrangement

• US 5,978,195 A
• Filed: 02/23/1998
• Issued: 11/02/1999
• Est. Priority Date: 02/23/1998
• Status: Expired due to Fees

• Current Assignee: MMC Bidding, Inc.
• Original Assignee: American National Bank And Trust Company Of Chicago
• Inventors: Pelletier, William, Goder, Dimitry
• Primary Examiner(s): Gaffin, Jeffrey
• Assistant Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US09/027,682
• Time in Patent Office: 617 Days
• Field of Search: 361/86, 361/18, 361/71, 361/74, 361/93-94, 323/274-277, 363/50
• US Class Current: 361/94
• CPC Class Codes: H02H 7/1227 responsive to abnormalities in the output circuit, e.g. short circuit
• CPC Class Codes: H02H 9/001 limiting speed of change of electric quantities, e.g. soft switching on or off progressive control of electronic switches for eliminating interferences H03K17/16

Abstract

A fault protection arrangement for protecting power conversion circuits, for example switch mode power supplies and the like, from overcurrent and short circuit faults. The fault protection arrangement includes multiple fault protection features, for example soft-start delay, fault delay and automatic reset, with the timing of each of these three features capable of being set independently of the other two while minimizing integrated circuit (IC) pin count and also minimizing the number of external components required for programming the timing of these features. The fault protection circuit may be used to advantage with any power conversion regulator topology.

Claims

1. A fault protection arrangement, for protecting a power conversion circuit from overcurrents, the power conversion circuit having

a power conversion circuit input, in use, coupled to a power source,

a power conversion circuit output having an output voltage, the power conversion circuit output, in use, coupled to a load, and

control means for controlling operation of the power conversion circuit, the power conversion circuit supplying power to the load when the control means is in an enabled state and not supplying power to the load when the control means is in a disabled state,

the fault protection arrangement comprising

soft-start means for delaying operation of the fault protection arrangement for a first predetermined time when the power conversion circuit is coupled to the power source,

comparison means having a comparison means input and a comparison means output, the comparison means input coupled to the power conversion circuit output, the comparison means output in a normal state when the power conversion circuit output voltage is above a predetermined fault voltage and in a fault state when the power conversion circuit output voltage is below the fault voltage,

a control output coupled to the control means, the control output causing the control means to switch from the enabled state to the disabled state when the comparison means output changes from the normal state to the fault state,

fault delay means for delaying the control output a second predetermined time in changing the control means from the enabled state to the disabled state after the comparison means output changes from the normal state to the fault state, and

reset means for resetting the control means to the enabled state a third predetermined time after the comparison means output changes from the normal state to the fault state,

wherein the first predetermined time, the second predetermined time and the third predetermined time are all determined by a common capacitance.

2. A fault protection arrangement according to claim 1, wherein the first predetermined time is determined by the common capacitance and a first reference voltage, the second predetermined time is determined by the common capacitance and a second reference voltage, and the third predetermined time is determined by the common capacitance and a third reference voltage.

3. A fault protection arrangement according to claim 1, wherein the power conversion circuit is a switch mode power supply.

4. A fault protection arrangement according to claim 1, wherein the comparison means comprises a comparator, the comparator having a first input which is coupled to the power conversion circuit output.

5. A fault protection arrangement according to claim 4, wherein the comparator has a second input which is coupled to a fault reference voltage.

6. A fault protection arrangement according to claim 1, wherein the fault delay means comprises a comparator, the comparator having a first input which is coupled to the common capacitance.

7. A fault protection arrangement according to claim 6, wherein the comparator has a second input which is coupled to a delay reference voltage.

8. A fault protection arrangement according to claim 1, wherein the reset means comprises a comparator, the comparator having a first input which is coupled to the common capacitance.

9. A fault protection arrangement according to claim 8, wherein the comparator has a second input which is coupled to a reset reference voltage.

10. A fault protection arrangement according to claim 1, wherein the soft-start means comprises a comparator, the comparator having a first input which is coupled to the common capacitance.

11. A fault protection arrangement according to claim 10, wherein the comparator has a second input which is coupled to a soft-start reference voltage.

12. A fault protection arrangement according to claim 1 wherein the control output comprises a flip-flop.

13. A fault protection arrangement, for protecting a power conversion circuit from overcurrents, the power conversion circuit having

a power conversion circuit input, in use, coupled to a power source,

a power conversion circuit output having an output voltage, the power conversion circuit output, in use, coupled to a load, and

control means for controlling operation of the power conversion circuit, the power conversion circuit supplying power to the load when the control means is in an enabled state and not supplying power to the load when the control means is in a disabled state,

the fault protection arrangement comprising

soft-start means for delaying operation of the fault protection arrangement for a first predetermined time when the power conversion circuit is coupled to the power source,

comparison means having a comparison means input and a comparison means output, the comparison means input coupled to the power conversion circuit output, the comparison means output in a normal state when the power conversion circuit output voltage is above a predetermined fault voltage and in a fault state when the power conversion circuit output voltage is below the fault voltage,

a control output coupled to the control means, the control output causing the control means to switch from the enabled state to the disabled state when the comparison means output changes from the normal state to the fault state,

fault delay means for delaying the control output a second predetermined time in changing the control means from the enabled state to the disabled state after the comparison means output changes from the normal state to the fault state, and

reset means for resetting the control means to the enabled state a third predetermined time after the comparison means output changes from the normal state to the fault state,

wherein the first predetermined time is determined by a soft-start reference voltage and a common capacitance, the second predetermined time is determined by a fault delay reference voltage and the common capacitance, and the third predetermined time is determined by a reset reference voltage and the common capacitance.

14. A fault protection arrangement, for protecting a power conversion circuit from overcurrents, the power conversion circuit having

a power conversion circuit input, in use, coupled to a power source,

a power conversion circuit output having an output voltage, the power conversion circuit output, in use, coupled to a load, and

control means for controlling operation of the power conversion circuit, the power conversion circuit supplying power to the load when the control means is in an enabled state and not supplying power to the load when the control means is in a disabled state,

the fault protection arrangement comprising

soft-start means for delaying operation of the fault protection arrangement for a first predetermined time when the power conversion circuit is coupled to the power source,

comparison means having a comparison means input and a comparison means output, the comparison means input coupled to the power conversion circuit output, the comparison means output in a normal state when the power conversion circuit output voltage is above a predetermined fault voltage and in a fault state when the power conversion circuit output voltage is below the fault voltage,

a control output coupled to the control means, the control output causing the control means to switch from the enabled state to the disabled state when the comparison means output changes from the normal state to the fault state and,

reset means for resetting the control means to the enabled state a second predetermined time after the comparison means output changes from the normal state to the fault state,

wherein the first predetermined time and the second predetermined time are determined by a common capacitance.

15. A fault protection arrangement according to claim 14, wherein the first predetermined time is determined by the common capacitance and a first reference voltage, and the second predetermined time is determined by the common capacitance and a second reference voltage.