Computer real time clockpower supply circuit

• US 5,778,239 A
• Filed: 03/11/1997
• Issued: 07/07/1998
• Est. Priority Date: 12/30/1994
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Cox, B. Tod
• Primary Examiner(s): AUVE, GLENN ALLEN
• Application Number:
  US08/814,557
• Time in Patent Office: 483 Days
• Field of Search: 395/750, 395/750.08, 364/707, 307/64-66
• US Class Current: 713/340
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision

Abstract

A power supply circuit is provided for a battery powered real time clock in a microprocessor based computer system. The power supply circuit monitors the output of the original battery and provides a warning indication when the battery output begins to drift or fade. A replacement battery may then be connected to the circuit. The circuit then substitutes power from the replacement battery for that from the original battery.

Claims

1. A power supply circuit for a real time clock in a computer system for automatically substituting a replacement clock battery for an original clock battery providing electrical power at a supply outlet to the real time clock, comprising:

first voltage monitor means for sensing the output of an original clock battery and monitoring the status of such original clock battery output;

connector means for receiving a replacement clock battery to receive electrical power therefrom; and

means for switching supply of power at the supply outlet from an original clock battery to a replacement clock battery once a replacement clock battery is attached to said connector means without removing said original clock battery from the computer system.

2. The circuit of claim 1, further including:

second voltage monitor means connected to said connector means for sensing the output of the replacement battery when same is connected to said connector means.

3. The circuit of claim 2, further including:

a replacement battery connected to said second voltage monitor means.

4. The circuit of claim 3, wherein:

said replacement battery comprises a rechargeable battery.

5. The circuit of claim 1, further including:

means responsive to said first voltage monitor means for indicating an unsatisfactory output status of the original battery.

6. The circuit of claim 1, wherein:

said connector means comprises a plurality of battery connectors connected in parallel, each adapted to receive electrical power from a replacement battery.

7. The circuit of claim 1, wherein:

said switch means comprises an automatically operable electrical switch.

8. The circuit of claim 1, wherein:

said switch means comprises a manually operable switch.

9. The circuit of claim 1, wherein said switch means comprises:

an automatically operable electrical switch; and

a manually operable switch;

each of said switches operable to switch supply of power at the supply outlet.

10. The circuit of claim 1, further including:

disabling means connected to said means for switching for disabling connection of the output of the original battery to the supply outlet when a replacement battery is attached to said connector means.

11. The circuit of claim 1, further including:

a battery connected to said first voltage monitor means.

12. In a computer system having a real time clock and an original clock battery powering the real time clock, a power supply circuit for automatically substituting a rechargeable battery for a non-chargeable battery providing electrical power at a supply outlet to the real time clock, comprising:

a clock battery to supply power to the real time clock as the original clock battery;

first voltage monitor means for sensing the output of the original clock battery and monitoring the status of the original clock battery output;

connector means for receiving a replacement clock battery to receive electrical power therefrom; and

means for switching supply of power at the supply outlet from said original clock battery to said connector means once a replacement clock battery is attached to said connector means without removing said original clock battery from the computer system.

13. The computer system of claim 12, further including:

second voltage monitor means connected to said connector means for sensing the output of the replacement battery when same is connected to said connector means.

14. The computer system of claim 13, further including:

a replacement battery connected to said second voltage monitor means.

15. The system of claim 14, wherein:

said replacement battery comprises a rechargeable battery.

16. The system of claim 12, further including:

means responsive to said first voltage monitor means for indicating an unsatisfactory output status of the original battery.

17. The system of claim 12, wherein:

said connector means comprises a plurality of battery connectors connected in parallel, each adapted to receive electrical power from a replacement battery.

18. The system of claim 12, wherein:

said switch means comprises an automatically operable electrical switch.

19. The system of claim 12, wherein:

said switch means comprises a manually operable switch.

20. The system of claim 12, wherein said switch means comprises:

an automatically operable electrical switch; and

a manually operable switch;

each of said switches operable to switch supply of power at the supply outlet.

21. The system of claim 12, further including:

disabling means connected to said means for switching for disabling connection of the output of the original battery to the supply outlet when a replacement battery is attached to said connector means.

22. The computer system of claim 12, wherein the computer system has a supply of regular power for the real time clock when the computer is operating and further including:

a circuit connected to the supply outlet for furnishing regular computer power to the real time clock when the computer is operating.

23. The computer system of claim 22, further including:

protective means for isolating said first voltage monitor means from the regular computer system power supply.

24. The computer system of claim 22, including:

protective means for isolating said first voltage monitor means from the regular computer system power supply;

second voltage monitor means connected to said connector means for sensing the output of the replacement clock battery when same is connected to said connector means; and

protective means for isolating said second voltage monitor means from the regular computer system power supply.

25. A method of automatically substituting a replacement clock battery for an original clock battery, the computer system having a supply outlet for providing power to a real time clock, comprising the steps of:

sensing the output of an original clock battery;

monitoring the status of the output of the original clock battery;

switching power at the supply outlet from the original clock battery to a replacement clock battery; and

maintaining the original clock battery in the computer system.

26. The method of claim 25, further comprising the step of:

maintaining power at the supply outlet at the replacement clock battery such that power at the supply outlet is not switched back to the original clock battery.

27. The method of claim 26, wherein the original clock battery is a non-rechargeable battery.

28. The method of claim 25, wherein the replacement clock battery is a rechargeable battery.

29. The method of claim 25, wherein said step of monitoring original clock battery status comprises monitoring the original clock battery status to detect a variance in the output of the original clock battery.

30. The method of claim 29, wherein a variance in the original clock battery output is detected during said step of monitoring, and wherein:

said step of switching is performed without removing the original clock battery.

31. In a computer system having a real time clock and an original clock battery powering the real time clock, a power supply circuit for automatically substituting a replacement clock battery for the original clock battery providing electrical power at a supply outlet to the real time clock, comprising:

an original clock battery to supply power to the real time clock;

voltage monitor means for sensing the output of the original clock battery and monitoring the status of the original clock battery output;

connector means for receiving a replacement clock battery to receive electrical power therefrom;

means for switching supply of power at the supply outlet from said original clock battery to said connector means without removing said original battery when a predetermined variance is detected in the original clock battery output; and

disabling means connected to said switching means for disabling connection of the output of the original clock battery to the supply outlet when a predetermined variance is detected in the original clock battery output.

32. The computer system of claim 31, wherein the replacement clock battery is connected to the connector means.

33. In a computer system having a real time clock and an original clock battery powering the real time clock, a power supply circuit for automatically substituting a replacement clock battery for the original clock battery providing electrical power at a supply outlet to the real time clock, comprising:

an original clock battery to supply power to the real time clock;

voltage monitor means for sensing the output of the original clock battery and monitoring the status of the original clock battery output;

connector means for receiving a replacement clock battery to receive electrical power therefrom;

disabling means for disabling connection of the output of the original clock battery to the supply outlet;

protective means for preventing current from recharging the original clock battery; and

means for switching supply of power at supply outlet from said original clock battery to said connector means without removing said original clock battery when the current is prevented from recharging the original clock battery by said protective means.

34. The computer system of claim 33, wherein the replacement clock battery is connected to the conector means.

35. A power supply circuit for a real time clock in a computer system for automatically substituting a replacement clock battery for an original clock battery providing electrical power at a supply outlet to the real time clock, comprising:

a first voltage monitor for sensing the output of an original clock battery and monitoring the status of such original clock battery output;

a connector for receiving a replacement clock battery to receive electrical power therefrom; and

a switch for switching supply of power at the supply outlet from an original clock battery to a replacement clock battery once a replacement clock battery is attached to said connector means without removing said original clock battery from the computer system.

36. The circuit of claim 35, further including:

a second voltage monitor connected to said connector for sensing the output of a replacement clock battery when same is connected to said connector.

37. The circuit of claim 36, further including:

a replacement clock battery connected to said second voltage monitor.

38. The circuit of claim 37, wherein:

said replacement clock batter comprises a rechargeable battery.

39. The circuit of claim 35, further in including:

battery status logic responsive to said first voltage monitor for indicating an unsatisfactory output status of the original clock battery.

40. The circuit of claim 35, wherein:

said connector comprises a plurality of battery connectors connected in parallel, each adapted to receive electrical power from a replacement clock battery.

41. The circuit of claim 35, wherein:

said switch comprises an automatically operable electrical switch.

42. The circuit of claim 35, wherein:

said switch comprises a manually operable switch.

43. The circuit of claim 35, wherein said switch comprises:

an automatically operable electrical switch; and

a manually operable switch;

each of said switches operable to switch supply of power at the supply outlet.

44. The circuit of claim 35, further including:

disabling logic connected to said switch for disabling connection of the output of the original clock battery to the supply outlet when a replacement clock battery is attached to said connector.

45. The circuit of claim 35, further including:

a clock battery connected to said first voltage monitor.

46. In a computer system having a real time clock and an original clock battery powering the real time clock, a power supply circuit for automatically substituting a rechargeable battery for a non-chargeable battery providing electrical power at a supply outlet to the real time clock, comprising:

a clock battery to supply power to the real time clock as the original clock battery;

a first voltage monitor for sensing the output of the original clock battery and monitoring the status of the original clock battery output;

a connector for receiving a replacement clock battery to receive electrical power therefrom; and

a switch for switching supply of power at the supply outlet from said original clock battery to said connector once a replacement clock battery is attached to said connector without removing said original clock battery from the computer system.

47. The computer system of claim 46, further including:

second voltage monitor connected to said connector for sensing the output of a replacement clock battery when same is connected to said connector.

48. The computer system of claim 47, further including:

a replacement clock battery connected to said second voltage monitor.

49. The computer system of claim 48, wherein:

said replacement clock battery comprises a rechargeable battery.

50. The computer system of claim 46, further including:

status detection logic responsive to said first voltage monitor for indicating an unsatisfactory output status of the original clock battery.

51. The computer system of claim 46, wherein:

said connector comprises a plurality of battery connectors connected in parallel, each adapted to receive electrical power from a replacement clock battery.

52. The computer system of claim 46, wherein:

said switch comprises an automatically operable electrical switch.

53. The computer system of claim 46, wherein:

said switch comprises a manually operable switch.

54. The computer system of claim 46, wherein said switch comprises:

an automatically operable electrical switch; and

a manually operable switch;

each of said switches operable to switch supply of power at the supply outlet.

55. The computer system of claim 46, further including:

disabling logic connected to said switch for disabling connection of the output of the original clock battery to the supply outlet when a replacement clock battery is attached to said connector.

56. The system of claim 46, wherein the computer system has a supply of regular power for the real time clock when the computer is operating and further including:

a circuit connected to the supply outlet for furnishing regular computer power to the real time clock when the computer is operating.

57. The computer system of claim 56, further including:

protection logic for isolating said first voltage monitor from the regular computer system power supply.

58. The computer system of claim 56, further including:

first protection logic for isolating said first voltage monitor from the regular computer system power supply;

second voltage monitor connected to said connector for sensing the output of the replacement clock battery when same is connected to said connector and;

second protection logic for isolating said second voltage monitor from the regular computer system power supply.