Computer memory system with a low power down mode

• US 6,243,315 B1
• Filed: 12/31/1999
• Issued: 06/05/2001
• Est. Priority Date: 12/31/1999
• Status: Expired due to Term

• Current Assignee: James Goodman
• Original Assignee: James Goodman
• Inventors: Goodman, James B.
• Primary Examiner(s): Hoang, Huan
• Time in patent office: 522 Days
• Field of Search: 365/222, 365/51, 365/63, 365/52, 365/230.03, 365/229
• US Class Current: 365/222
• CPC Class Codes: G11C 11/406 Management or control of the refreshing or charge-regeneration cycles
• CPC Class Codes: G11C 11/4072 Circuits for initialization, powering up or down, clearing memory or presetting
• CPC Class Codes: G11C 7/1045 Read-write mode select circuits

Abstract

A memory system for use in a computer system, includes a plurality of volatile solid state memory devices that retain information when an electrical power source is applied to the memory devices within a predetermined voltage range, and are capable of being placed in a self refresh mode. The memory devices have respective address and control lines, and a control device for selectively electrically isolating the memory devices from respective address lines and respective control lines so that when the memory devices are electrically isolated, any signals received on the respective address lines and respective control lines do not reach the memory devices. The memory system includes a memory access enable control device coupled to the control device and to the control lines for determining when the memory system is not being accessed, and for initiating a low power mode for the memory system wherein the control device electrically isolates the memory devices and places the memory devices in the self refresh mode.

Claims

1. A memory system for use in a computer system, said memory system comprising:

a plurality of volatile solid state memory devices that retain information when an electrical power source is applied to said memory devices within a predetermined voltage range and capable of being placed in a self refresh mode;

said memory devices having address lines and control lines;

a control device for selectively electrically isolating said memory devices from respective address lines and respective control lines so that when said memory devices are electrically isolated, any signals received on said respective address lines and respective control lines do not reach said memory devices; and

a memory access enable control device coupled to said control device and to said control lines for determining when said memory system is not being accessed and for initiating a low power mode for said memory system wherein said control device electrically isolates said memory devices and places said memory devices in said self refresh mode, thereby reducing the amount of electrical energy being drawn from an electrical power supply for said computer system.

2. The memory system as claimed in claim 1, wherein said system is compatible with the dimensions and pin assignments an JEDEC industry standard 144 PIN SODIMM connector.

3. The memory system as claimed in claim 1, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 168 PIN DIMM connector.

4. The memory system as claimed in claim 3, said memory system further comprising serial presence detect circuitry in accordance with the JEDEC industry standard.

5. The memory system as claimed in claim 1, wherein the memory devices are DRAM semiconductor microchips.

6. The memory system as claimed in claim 5, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 144 PIN SODIMM connector.

7. The memory system as claimed in claim 6, said memory system further comprising serial presence detect circuitry in accordance with the JEDEC industry standard.

8. The memory system as claimed in claim 5, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 168 PIN DIMM connector.

9. The memory system as claimed in claim 8, said memory system further comprising serial presence detect circuitry in accordance with the JEDEC industry standard.

10. A memory system for use in a computer system, said memory system comprising:

a plurality of volatile solid state memory devices that retain information when an electrical power source having a voltage greater than a predetermined voltage is applied to said devices;

said memory devices having address lines and control lines;

said computer system including a first electrical power source for operating said computer and being capable of producing a first voltage applied to said memory devices;

a control device for monitoring said first voltage to determine when said first voltage is less than said predetermined voltage and for selectively electrically isolating said memory devices from respective address lines and respective control lines so that when said memory devices are electrically isolated, any signals received on said respective address lines and respective control lines do not reach said memory devices; and

a second electrical power source operable for supplying a second voltage to said memory devices greater than said predetermined voltage;

said control device being operable for disconnecting said first electrical power source from said memory devices and connecting said second electrical power source to said memory devices when said first voltage is less than said predetermined voltage;

whereby, data in said memory devices is preserved by said second electrical power source when said first electrical power source fails to maintain at least said predetermined voltage on said memory devices, and said memory devices are isolated from errant signals.

11. The memory system as claimed in claim 10, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 72 PIN SIMM connector.

12. The memory system as claimed in claim 10, wherein said system is compatible with the dimensions and pin assignments an JEDEC industry standard 144 PIN SODIMM connector.

13. The memory system as claimed in claim 12, said memory system further comprising serial presence detect circuitry in accordance with the JEDEC industry standard.

14. The memory system as claimed in claim 10, wherein said system is compatible with the dimensions and pin assignments an JEDEC industry standard 168 PIN DIMM connector.

15. The memory system as claimed in claim 14, said memory system further comprising serial presence detect circuitry in accordance with the JEDEC industry standard.

16. The memory system as claimed in claim 10, wherein said memory devices are DRAM semiconductor microchips.

17. The memory system as claimed in claim 16, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 144 PIN SODIMM connector.

18. The memory system as claimed in claim 16, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 72 PIN SIMM connector.

19. The memory system as claimed in claim 16, wherein said system is compatible with the dimensions and pin assignments in accordance with JEDEC industry standard 168 PIN DIMM connector.

20. The memory system as claimed in claim 19, said memory system further comprising serial presence detect circuitry in accordance with the JEDEC industry standard.