Current monitoring and latchup detection circuit and method of operation

An apparatus for monitoring a load current drawn by an electrical circuit in a wire includes: 1) a Lorentz force MOS transistor having a first drain current (ID

1) and a second drain current (ID

2), wherein the Lorentz force MOS transistor is disposed proximate the wire carrying the load current and wherein a magnetic force generated by the load current increases a first current difference between the first drain current and a second drain current; 2) a current difference amplification circuit for detecting the first current difference between the first drain current and the second drain current and generating an amplified output signal; and 3) a current monitoring circuit coupled to the current difference amplification circuit capable of detecting and measuring the amplified output signal.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, and in which:

FIG. 1 illustrates an exemplary prior art magnetic field detection transistor (or MagFET);

FIG. 2 illustrates a current difference detection circuit using the exemplary MagFET according to one embodiment of the present invention;

FIG. 3 illustrates a monitoring circuit capable of monitoring the current drawn by an active circuit and detecting a latchup or other over-current condition, according to one embodiment of the present invention;

FIGS. 4A and 4B illustrate different configurations of current-carrying wires monitored by the exemplary MagFET according to alternate embodiments of the present invention; and

FIG. 5 is a flow diagram illustrating the operation of the exemplary monitoring circuit in FIG. 3 according to one embodiment of the present invention.

1. An apparatus for monitoring a load current drawn by an electrical circuit in a wire, said apparatus comprising:

2. The apparatus as set forth in claim 1 wherein said current detection circuit further comprises:

3. The apparatus as set forth in claim 1 wherein said Lorentz force MOS transistor is disposed within a loop formed by said wire.

4. The apparatus as set forth in claim 3 wherein said Lorentz force MOS transistor is disposed within a plurality of concentric loops formed by said wire.

5. An apparatus for monitoring a load current drawn by an electrical circuit in a wire, said apparatus comprising:

6. The apparatus as set forth in claim 5 further comprising a switch controlled by said current monitoring circuit capable of coupling said wire to a power supply.

7. The apparatus as set forth in claim 6 wherein said current monitoring circuit opens said switch and measures said amplified output signal when said load current is zero to thereby determine an initial current difference reference.

8. The apparatus as set forth in claim 7 wherein said current monitoring circuit closes said switch and measures said amplified output signal to determine said first current difference.

9. An integrated circuit comprising:

10. The integrated circuit as set forth in claim 9 wherein said current detection circuit further comprises:

11. The integrated circuit as set forth in claim 9 wherein said Lorentz force MOS transistor is disposed within a loop formed by said power supply wire.

12. The integrated circuit as set forth in claim 11 wherein said Lorentz force MOS transistor is disposed within a plurality of concentric loops formed by said power supply wire.

13. An integrated circuit comprising:

14. The integrated circuit as set forth in claim 13 further comprising a switch controlled by said current monitoring circuit capable of coupling said power supply wire to a power supply.

15. The integrated circuit as set forth in claim 14 wherein said current monitoring circuit opens said switch and measures said amplified output signal when said load current is zero to thereby determine an initial current difference reference.

16. The integrated circuit as set forth in claim 15 wherein said current monitoring circuit closes said switch and measures said amplified output signal to determine said first current difference.

17. A method for monitoring a load current in a power supply wire coupling a power supply and electrical circuit, wherein the wire is disposed proximate a Lorentz force MOS transistor having a first drain current (ID

1) and a second drain current (ID

2), the method comprising the steps of:

18. The method as set forth in claim 17 wherein the steps of detecting the first current difference and generating the output signal comprises the sub-steps of amplifying the first current difference in a differential amplifier stage and generating a differential output voltage corresponding to the first current difference.

19. The method as set forth in claim 17 wherein the Lorentz force MOS transistor is disposed within a loop formed by the power supply wire.

20. The method as set forth in claim 19 wherein the Lorentz force MOS transistor is disposed within a plurality of concentric loops formed by the power supply wire.

21. A method for monitoring a load current in a power supply wire coupling a power supply and electrical circuit, wherein the wire is disposed proximate a Lorentz force MOS transistor having a first drain current (ID

1) and a second drain current (ID

2), the method comprising the steps of: