Printed circuit board having conductors which can be decoupled for isolating inactive integrated circuits connected thereto

• US 5,796,566 A
• Filed: 08/16/1996
• Issued: 08/18/1998
• Est. Priority Date: 08/16/1996
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Clark, Gordon R., Sharma, Dinesh, Alton, Lawrence E.
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US08/695,829
• Time in Patent Office: 732 Days
• Field of Search: 361/18, 361/86, 361/92, 307/85-86, 307/48, 307/64, 307/66, 307/130, 365/226-229
• US Class Current: 361/86
• CPC Class Codes: G06F 13/4081 Live connection to bus, e.g. hot-plugging current or voltage limitation during live insertion H02H9/004
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

A communication system is presented whereby sequences of video screens sent from a host CPU to a video controller can be stored and subsequently retrieved by a terminal located remote from the host CPU. Detection logic, controller memory, processor and a communication unit are compiled as a system configured upon a PCB. The PCB is configured to maintain certain vital functions even if power supplied from an expansion bus ceases. The PCB may employ a battery which maintains processor and controller memory activities and communication therebetween for a period of time sufficient to sustain video screen information stored within the controller memory. Thus, decoupling circuitry is present which prevents drain upon the battery if the communication unit is not being used. The decoupling unit separates power and signal conductors between portions of the printed circuit board. A power status signal is indicative of the voltage level within power conductors of one portion relative to a voltage level within power conductors of another portion to effectuate decoupling therebetween.

Claims

1. A printed circuit board, comprising:

a first power conductor extending across a first portion of said printed circuit board;

a second power conductor extending across a second portion of said printed circuit board;

a decoupling unit connected between said first power conductor and said second power conductor, wherein said decoupling unit causes disconnect of said first power conductor from said second power conductor during times in which voltage within said first power conductor is less than voltage within said second power conductor, and wherein said second portion comprises a switching regulator, a battery, and a processor arranged thereon, and wherein said switching regulator causes coupling of said battery to said processor during times in which voltage within said first power conductor is less than voltage within said second power conductor.

2. A printed circuit board, comprising:

a first power conductor extending across a first portion of said printed circuit board;

a second power conductor extending across a second portion of said printed circuit board;

a decoupling unit connected between said first power conductor and said second power conductor, wherein said decoupling unit causes disconnect of said flat power conductor from said second power conductor during times in which voltage within said first power conductor is less than voltage within said second power conductor; and

a charge conductor extending from said first portion to said second portion for charging a battery arranged within said second portion during times in which voltage within said first power conductor is not less than voltage within said second power conductor by a predetermined amount.

3. A printed circuit board, comprising:

a first power conductor extending across a first portion of said printed circuit board;

a second power conductor extending across a second portion of said printed circuit board;

a decoupling unit connected between said first power conductor and said second power conductor, wherein said decoupling unit causes disconnect of said first power conductor from said second power conductor during times in which voltage within said first power conductor is less than voltage within said second power conductor;

a first signal conductor extending across said first portion, and a second signal conductor extending across said second portion; and

said decoupling unit causes disconnect of said first signal conductor from said second signal conductor during times in which voltage within said first power conductor is less than voltage within said second power conductor.

4. A printed circuit board, comprising:

a first power conductor and a first signal conductor extending across a first portion of said printed circuit board;

a second power conductor and a second signal conductor extending across a second portion of said printed circuit board;

a third power conductor and a third signal conductor extending across a third portion of said printed circuit board;

a first decoupling unit connected between said first power conductor and said second power conductor as well as between said first signal conductor and said second signal conductor;

a second decoupling unit connected between said second power conductor and said third power conductor as well as between said second signal conductor and said third signal conductor;

a power status signal indicative of the voltage level within said first power conductor relative to the voltage level within said second power conductor for causing said first decoupling unit to decouple said first and second power conductors as well as to decouple said first and second signal conductors; and

a communication signal indicative of communication to an integrated circuit arranged within said second portion for causing said second decoupling unit to couple said second and third power conductors as well as to couple said second and third signal conductors.

5. The printed circuit board as recited in claim 4, wherein said power status signal comprises VDDOFF.

6. The printed circuit board as recited in claim 4, wherein said integrated circuit comprises a modem, and wherein said communication signal comprises a ring signal (DRNG) arising from a ring indicator unit arranged upon said printed circuit board.

7. The printed circuit board as recited in claim 6, wherein said ring indicator produces said ring signal upon receiving communication from a terminal arranged remote from said printed circuit board.

8. The printed circuit board as recited in claim 4, wherein said integrated circuit comprises a modem which, upon receiving said communication signal, initiates a modem active signal (MDMACT) to a processor arranged within said second portion, and wherein said processor responds to said modem active signal by sending a modem power signal (MDMPWR) to said second decoupling unit to couple said second and third power conductors as well as to couple said second a third signal conductors.

9. The printed circuit board as recited in claim 4, wherein absence of said communication signal is indicative of non-communication to an integrated circuit arranged within said second portion for causing said second decoupling unit to decouple said second and third power conductors as well as to decouple said second and third signal conductors.

10. The printed circuit board as recited in claim 4, wherein said power status signal is asserted during times in which voltage within said first power conductor is less than voltage within said second power conductor.

11. The printed circuit board as recited in claim 4, wherein said first portion is configured to receive an EISA bus interface unit and an EISA bus buffer.

12. The printed circuit board as recited in claim 4, wherein said second portion is configured to receive a processor and a battery-backed power supply.

13. The printed circuit board as recited in claim 4, wherein the voltage within said second power conductor is supplied from a battery arranged within said second portion.

14. The printed circuit board as recited in claim 4, wherein said second portion comprises a switching regulator, a battery, and a processor arranged thereon, and wherein said switching regulator causes coupling of said battery to said processor during times in which voltage within said first power conductor is less than voltage within said second power conductor.

15. The printed circuit board as recited in claim 4, further comprising a charge conductor extending from said first portion to said second portion for charging a battery arranged within said second portion during times in which voltage within said first power conductor is not less than voltage within said second power conductor by a predetermined amount.

16. A method for providing secondary power to select integrated circuits during times when primary power is removed, comprising:

providing a printed circuit board having a processor integrated circuit and a modem integrated circuit arranged thereon;

forwarding primary power to the processor and modem during a first time period in which said primary power is available;

forwarding secondary power to the processor and modem during a second time period in which said primary power is unavailable and said modem is receiving a ring signal; and

disconnecting said secondary power to said modem during a third time period in which said primary power is unavailable and said modem is not receiving a ring signal.

17. The method as recited in claim 16, wherein said primary power is available through an edge connector arranged near the periphery of said printed circuit board.

18. The method as recited in claim 16, wherein said secondary power is derived from a battery.

19. The method as recited in claim 16, wherein said secondary power comprises a battery charged from said primary power during said first time period.

20. The method as recited in claim 16, wherein said ring signal is provided from a ring detector powered by said secondary power during said second and third time periods.

21. The method as recited in claim 16, wherein said disconnecting said secondary power comprises connecting said secondary power to select conductors extending from said processor during said third time period.

22. The method as recited in claim 21, wherein said connecting comprises tri-stating signals within said select conductors.