Power line switching circuit with monitor

• US 5,404,542 A
• Filed: 10/19/1990
• Issued: 04/04/1995
• Est. Priority Date: 10/19/1990
• Status: Expired due to Fees

• Current Assignee: Everex Systems Incorporated (MidgardXXI, Inc.)
• Original Assignee: Everex Systems Incorporated (MidgardXXI, Inc.)
• Inventors: Cheung, Anthony
• Primary Examiner(s): Chun, Debra A.
• Assistant Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US07/600,438
• Time in Patent Office: 1,628 Days
• Field of Search: 395/750, 395/575, 395/275, 364/707, 364/273.5, 364/DIG. 1, 364/948.4, 364/948.91, 364/DIG. 2, 371/66, 371/12, 371/14
• US Class Current: 713/300
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H04L 25/0298 Arrangement for terminating transmission lines

Abstract

A power line coupling and decoupling circuit for furthering peripheral system reliability. The circuit is used in a computer system which includes a host computer attached to a peripheral system via a SCSI communication interface. A light emitting diode is used as a monitor to indicate the power level on the SCSI interface. A mechanical slide switch is used to then couple or decouple a peripheral system'"'"'s power source and the SCSI interface thus preventing electrical short circuits and current surges within the peripheral system. The SCSI interface receives its power directly from the peripheral power source and not from a peripheral device assembled within the peripheral system.

Claims

1. A power line switching circuit for increasing reliability of a peripheral system coupled to a host computer, said power line switching circuit comprising:

(a) a primary power line;

(b) a peripheral power source coupled to said primary power line;

(c) a secondary power line for coupling with a communication interface, said communication interface coupled between said peripheral system and said host computer system;

(d) switching means coupled to said secondary power line and to said primary power line for electrically coupling said primary and said secondary power lines when said switching means is in a closed state in order to couple said communication line to said peripheral power source and for electrically decoupling said primary and secondary power lines when said switching means is in an open state in order to decouple said communication line from said peripheral power source; and

(e) monitor means coupled to said secondary power line for indicating whether or not said secondary power line is coupled to said peripheral power source or any source of power supplied over said communication interface, said monitor means receiving a voltage level on said secondary power line as an input signal.

2. The power line switching circuit as described in claim 1 wherein said switching means is a manually operated mechanical slide switch.

3. The power line switching circuit as described in claim 1 wherein said switching means is an electrically controlled electronic switch.

4. The power line switching circuit as described in claim 1 wherein said switching means is an electrically controlled mechanical switch.

5. The power line switching circuit as described in claim 1 wherein said switching means is a manually operated electronic switch.

6. The power line switching circuit as described in claim 1 wherein said monitor means is a Light Emitting Diode.

7. The power line switching circuit as described in claim 1 wherein a fuse is coupled between said switching means and said secondary power line.

8. The power line switching circuit as described in claim 1 wherein a diode is coupled between said switching means and said secondary power line.

9. The power line switching circuit as described in claim 1 wherein coupled between said switching means and said secondary power line is a series arrangement comprising a diode and a fuse.

10. The power line switching circuit as described in claim 1 wherein said primary power line is additionally coupled to a peripheral device.

11. The power line switching circuit as described in claim 1 wherein said secondary power line is coupled to a SCSI communication interface.

12. The power line switching circuit as described in claim 1 further comprising a Macintosh®

line computer and wherein said secondary power line is coupled to a SCSI communication interface of said Macintosh®

line computer.

13. In a SCSI communication interface, a power line circuit for use within a peripheral system, said peripheral system including a power driven active peripheral device with an output and a peripheral power source for said device, said peripheral system being adapted to interface with a host computer, said power line circuit comprising:

(a) pin means adapted to connect said peripheral system with said host computer over said SCSI communication;

(b) power line means for coupling said pin means with said peripheral power source, said power line means bypassing said peripheral device so as to electrically isolate said output of said device from said pin means;

(c) user replaceable fuse means coupled between said pin means and said peripheral power source;

(d) switching means coupled between said pin means and said peripheral power source for electrically coupling or decoupling said pin means from said peripheral system; and

(e) monitor means coupled between said switching means and said pin means for indicating whether or not said peripheral power source, or any other power source over said SCSI communication interface, is coupled to said pin means.

14. A power line circuit for use within a peripheral system to increase peripheral system reliability, said peripheral system being adapted to interface with a host computer, said power line circuit comprising:

(a) pin means adapted to connect said peripheral system with said host computer, said pin means for coupling to a communication interface, said peripheral system comprising a power driven active peripheral device with an output and a peripheral power source for said peripheral device;

(b) power line means for coupling said pin means with said peripheral power source, said power line means bypassing said peripheral device so as to electrically isolate said peripheral device from said pin means;

(c) switching means coupled between said pin means and said peripheral power source for electrically coupling or decoupling said pin means from said peripheral system; and

(d) monitor means coupled between said switching means and said pin means for indicating whether or not said pin means is coupled to said peripheral power source or any other power source over said communication interface.

15. A power line circuit for use within a peripheral system to increase peripheral system reliability as described in claim 14 wherein said communication interface is a SCSI communication interface.

16. A power line circuit for use within a peripheral system to increase peripheral system reliability as described in claim 15 wherein said peripheral device is a data storage and retrieval device.

17. In a computer system including a host computer, a peripheral system having a peripheral power source, and a communication interface for coupling said host computer with said peripheral system, the improvement for increasing peripheral system reliability, said improvement comprising:

(a) switching means for electrically coupling said peripheral power source to said communication interface and for electrically decoupling said peripheral power source from said communication interface,

(b) a primary line means for coupling said peripheral power source to said switching means, and

(c) a secondary line means for coupling said switching means to said communication interface, and

(d) means for monitoring whether or not said peripheral power source is coupled to said secondary line means or any other power source is coupled to said secondary line means through said communication interface.

18. The improvement as recited by claim 17 wherein said peripheral power source is an integral component of said peripheral system.

19. The computer system as recited by claim 17 wherein said switch means is a manually operated mechanical slide switch.

20. The computer system as recited by claim 17 wherein said monitor means is a Light Emitting Diode.

21. The computer system as recited by claim 17 wherein said host computer is a Macintosh®

computer.

22. The computer system as recited by claim 17 wherein said communication interface is a SCSI standard interface.

23. A peripheral system having increased reliability, said peripheral system comprising:

(a) a power source;

(b) at least one active peripheral device coupled to said power source;

(c) a communication interface pin, said pin for coupling to a first power line of a communication interface between a host computer and said peripheral system;

(d) a switching means for electrically coupling said power source to said communication interface pin and for electrically decoupling said power source from said communication interface pin, said power source is coupled to said switching means by a primary line and wherein said switching means is coupled to said communication interface pin by a secondary power line, and

(e) monitor means coupled to said secondary line for indicating whether or not said power source is connected to said secondary line or if a power source is coupled to said secondary line through said communication interface.

24. The peripheral system as recited in claim 23 wherein said secondary line is coupled to a SCSI communications interface.

25. The peripheral system as recited in claim 23 wherein said monitor means is a Light Emitting Diode.

26. The peripheral system as recited in claim 23 wherein said switch means is a mechanical slide switch.

27. A method of selectively providing power to a SCSI communication interface comprising the steps of:

(a) coupling at least one peripheral system having its own power source to a host computer through a SCSI communication interface, said SCSI communication interface having a number of interconnect pins;

(b) detecting power levels on at least one of the pins of said SCSI communication interface; and

(c) selectively coupling said power source to said SCSI communication interface or decoupling said power source from said SCSI communication interface depending on whether or not there is a power level on said one pin.

28. The method as recited in claim 27 including the step of visually indicating whether or not there is a power level on said one pin.

29. A power line switching circuit for use in supplying power to a particular line in a communication interface cooperating with a peripheral system which peripheral system is adapted to interface with a host computer, said power line switching circuit comprising:

(a) a primary power line;

(b) a peripheral power source coupled to said primary power line;

(c) a secondary power line adapted for connection with said communication interface line;

(d) a manually operated mechanical slide switch coupled to said secondary power line and to said primary power line for electrically coupling said primary and said secondary power lines when said slide switch is in a closed state in order to couple said communication line to said peripheral power source and for electrically decoupling said primary and secondary power lines when said slide switch is in an open state in order to decouple said communication line from said peripheral power source; and

(e) monitor means coupled to said secondary power line for indicating whether or not said secondary power line is coupled to said peripheral power source or any other source of power, said monitor means receiving a voltage level on said secondary power line as an input signal.