Two stage power supply circuit for independently supplying power to first and second components of a digital processing system

• US 7,076,670 B1
• Filed: 09/07/2000
• Issued: 07/11/2006
• Est. Priority Date: 09/07/2000
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Krause, Peter, Chong, Phuan Boon
• Primary Examiner(s): Browne, Lynne H.
• Assistant Examiner(s): YANCHUS III, PAUL B
• Application Number:
  US09/656,504
• Time in Patent Office: 2,133 Days
• Field of Search: 713/300, 713/320, 713/324, 713/330, 713/310, 345/211, 345/212, 363/21.04, 363/21.12, 363/16, 363/26
• US Class Current: 713/300
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C

Abstract

A power supply circuit for a digital processing system. A first stage of the power supply circuit is used to generate power for a first component of the digital processing system and to drive a second stage of the power supply circuit. The second stage of the power supply circuit supports a second component of the digital processing system. The first and second stages of the power supply circuit are electrically connected to each other.

Claims

1. A power supply circuit for a digital processing system, the circuit comprising:

a first stage having a first output coupled to a first component of the digital processing system, and a second output which is different from the first output, wherein said second output has an output winding;

a second stage associated with a second component of the digital processing system, and having an input winding, wherein said input winding of said second stage is directly connected to said output winding of said first stage through a two wire bus; and

wherein said first stage drives said second stage using the direct two-wire bus connection between said output winding of the second output and said input winding of said second stage, wherein the second stage transforms the second output to generate a third output to drive the second component, and wherein the first output is independent of the second stage.

2. The circuit of claim 1, wherein said first and second stages are separated from each other.

3. The circuit of claim 1, wherein said two wire bus is differentially driven by said first stage.

4. The circuit of claim 2, wherein said first component comprises a display device and said second component comprises a microprocessor.

5. The circuit of claim 4, wherein said first stage is located proximately to said display device and said second stage is located proximately to said microprocessor.

6. The circuit of claim 1, wherein said first stage provides power for said first component and said second stage provides power for said second component.

7. The circuit of claim 6, wherein said first stage comprises a flyback converter and said second stage comprises a portion of a forward converter.

8. The power supply circuit of claim 1, wherein said first output provides a direct (DC) voltage, and wherein said second output provides an alternating current (AC) voltage.

9. A power supply circuit for a computer system, the circuit comprising:

a first circuit having a first output capable of providing power to a first component of the computer system and a second output which is different from the first output, wherein said second output has an output winding; and

a second circuit having an input winding and capable of providing power to a second component of the computer system, wherein said input winding of said second circuit is directly connected to said output winding of said first circuit through a two wire bus;

wherein said first circuit drives the second circuit through the direct two-wire bus connection between said output winding of the second output and said input winding of said second stare, wherein the second circuit transforms the second output to generate a third output to drive the second component, and wherein the first output is independent of the second circuit.

10. The circuit of claim 9, wherein said second circuit and said second component are disposed on a printed circuit board.

11. The circuit of claim 9, wherein said first circuit is located within an enclosure of the computer system and proximately to said first component, and wherein said second circuit is located within said enclosure and proximately to said second component.

12. The circuit of claim 11, wherein said first component comprises a display device and said second component comprises a microprocessor.

13. The circuit of claim 9 wherein said first circuit comprises a flyback converter and said second circuit comprises a final stage of a forward converter.

14. The power supply circuit of claim 9, wherein said first output provides a direct current (DC) voltage and said second output provides an alternating current (AC) voltage.

15. A computer system comprising:

a power supply circuit coupled to a display device and a microprocessor of the computer system, wherein said power supply circuit is capable of supplying power to said display device and said microprocessor using at least two distinct power supply stages;

a main circuit having a first output and a second output, wherein said main circuit is coupled to said display device using said first output; and

a secondary circuit coupled to said microprocessor, said secondary circuit having an input winding, wherein said second output is directly connected to said input winding through a two wire bus; and

wherein said main circuit drives said secondary circuit using the direct two-wire bus connection between said output winding of said second output which is different from the first output, and said input winding of said second stage, wherein said secondary circuit transforms said second output to generate a third output to drive the microprocessor, and wherein the first output is independent of the secondary circuit.

16. The computer system of claim 15, wherein one of said at least two distinct power supply stages includes said main circuit, and wherein another of said at least two distinct power supply stages includes said secondary circuit.

17. The computer system of claim 15, wherein said main circuit and said secondary circuit are physically isolated from each other.

18. The computer system of claim 17, wherein said main circuit and said secondary circuit are electrically coupled to each other.

19. The computer system of claim 15, wherein said main circuit comprises a flyback converter and said secondary circuit comprises a portion of a forward converter.