Components having actively controlled circuit elements

1. Apparatus comprising

two or more electronic components, each of the components having an internal circuit having a controlled element and a control element, and terminals coupled to the internal circuit and adapted for surface mounting on a circuit board,

the internal circuits of the components being adapted to be connected in parallel through one of the terminals of each of the internal circuits to a common point of an external circuit and to cooperatively protect the external circuit against occurrence of one or more adverse electrical events, wherein the one or more adverse electrical events comprises the external circuit drawing more than a threshold amount of current,

wherein none of the electronic components has ratings sufficient by itself to protect the external circuit.

2. The apparatus of claim 1 in which one or more of the events comprises a loss of a source of power for the external circuit.

3. The apparatus of claim 1 in which one or more of the events comprises a sudden change in a voltage at a point of load of the external circuit.

4. The apparatus of claim 1 in which the controlled element comprises a FET.

5. The apparatus of claim 1 in which the internal circuit is adapted to detect a current reversal in a path between a power source and the external circuit, and a controlled element is controlled to disconnect the power source from the external circuit in response to the detection.

6. The apparatus of claim 1 in which the internal circuits are connected in parallel between a single power source and the external circuit.

7. The apparatus of claim 1 in which each of the internal circuits includes a voltage generator adapted to derive power from an external source and to provide a voltage to drive the internal circuit.

8. The apparatus of claim 1 in which each of the internal circuits includes circuitry adapted to monitor the voltage across the controlled element.

9. The apparatus of claim 1 in which the internal circuit comprises a FET and a control circuit connected to control the FET.

10. The apparatus of claim 9 in which the FET and the control circuit are formed on a single integrated substrate.

11. The apparatus of claim 9 in which the FET and the control circuit comprise discrete components mounted on a single substrate.

12. The apparatus of claim 10 or 11 in which the FET, the control circuit, and the terminals are part of a micro-lead package.

13. Apparatus comprising:

two or more electronic components, each of the components having

an internal circuit having a controlled element and a control element,

terminals coupled to the internal circuit and adapted for surface mounting on a circuit board, and

elements adapted to pull up a voltage at one of the terminals when the voltage at the terminal drops and elements adapted to pull down the voltage at the one of the terminals when the voltage at the terminal rises,

the internal circuits of the components being adapted to be connected in parallel through one of the terminals of each of the internal circuits to a common point of an external circuit and to cooperatively protect the external circuit against occurrence of an adverse electrical event.

14. The apparatus of claim 13 in which the elements comprise a DC-to-DC converter.

15. The apparatus of claim 14 wherein none of the electronic components has ratings sufficient by itself to protect the external circuit.

16. Apparatus comprising

a protection circuit, and

terminals for connecting the protection circuit respectively to a power source and to an external circuit that is to be powered by the source and protected by the protection circuit against an occurrence of an electrical event,

the protection circuit comprising a first and second protection mechanism, the protection mechanisms being connected to provide different kinds of protection for the external circuit using at least two controlled elements,

wherein the first protection mechanism provides a current drain on the power source to pull the voltage down at a point of load.

17. The apparatus of claim 16 in which the protection mechanisms are connected in series between the power source and the external circuit.

18. The apparatus of claim 16 in which the second protection mechanism includes two FETs connected in series.

19. The apparatus of claim 18 which the FETs are connected in a common drain configuration.

20. The apparatus of claim 18 in which the FETs are connected in a common source configuration.

21. The apparatus of claim 16 in which the protection circuit is adapted to be connected across the external circuit.

22. The apparatus of claim 21 in which the protection mechanisms include a FET.

23. The apparatus of claim 16 , in which the first protection mechanisms shunts current away from the external circuit.

24. The apparatus of claim 16 in which the second protection mechanisms delivers current to the external circuit.

25. The apparatus of claim 16 in which the first protection mechanism shunts current to ground.

26. The apparatus of claim 16 also including an energy reservoir at a predetermined voltage, and in which the first protection mechanism shunts current to the energy reservoir.

27. The apparatus of claim 16 in which the apparatus comprises an energy reservoir at a predetermined voltage, and in which the second protection mechanism delivers current from the energy reservoir.

28. Apparatus comprising

a protection circuit comprising two protection mechanisms connected across an external circuit;

terminals for connecting the protection circuit respectively to a power source and to the external circuit that is to be powered by the source and protected by the protection circuit against an occurrence of an electrical event, the protection circuit being connected to provide two different kinds of protection for the external circuit using at least two controlled elements; and

an energy reservoir at a predetermined voltage, wherein one of the protection mechanisms shunts current away from the external circuit to the energy reservoir.

29. Apparatus comprising

a protection circuit comprising two protection mechanisms connected across an external circuit;

terminals for connecting the protection circuit respectively to a power source and to the external circuit that is to be powered by the source and protected by the protection circuit against an occurrence of an electrical event, the protection circuit being connected to provide two different kinds of protection for the external circuit using at least two controlled elements; and

an energy reservoir at a predetermined voltage, wherein one of the protection mechanisms delivers current to the energy reservoir.