Apparatus and method for programming voltage protection in a non-volatile memory system

• US 6,552,933 B2
• Filed: 02/26/2002
• Issued: 04/22/2003
• Est. Priority Date: 01/08/1997
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Roohparvar, Frankie F.
• Primary Examiner(s): Le, Vu Anh
• Application Number:
  US10/082,971
• Publication Number:
  US 20020118571A1
• Time in Patent Office: 420 Days
• Field of Search: 365/185.18, 365/226, 365/228, 365/189.07
• US Class Current: 365/185.18
• CPC Class Codes: G11C 16/12 Programming voltage switching circuits
• CPC Class Codes: G11C 16/225 Preventing erasure, programming or reading when power supply voltages are outside the required ranges
• CPC Class Codes: G11C 5/143 Detection of memory cassette insertion or removal; Continuity checks of supply or ground lines; Detection of supply variations, interruptions or levels G11C5/148 takes precedence; Switching between alternative supplies G11C5/141 takes precedence

Abstract

A memory system including an array of memory cells, a programming voltage node for receiving a first programming voltage, a memory controller which controls memory programming operations on the array of memory cells, and voltage detection circuitry, operably coupled to the memory controller and the programming voltage node, with the voltage detection circuitry being configured to enable the memory controller to initiate one of the programming operations if the first programming voltage exceeds a first voltage level and to continue the programming operation once the programming operation has been initiated if the first programming voltage drops to a second voltage level and to terminate the programming operation once the programming operation has been initiated if the first programming voltage drops below the second voltage level, with the first voltage level being greater than the second voltage level. And a method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising the steps of providing a first programming voltage, initiating a memory programming operation if the first programming voltage magnitude exceeds a first voltage level, continuing the initiated programming operation if the first programming voltage remains greater in magnitude than a second voltage level, with the first voltage level magnitude being greater in magnitude than the second voltage level, and terminating the initiated programming operation if the first programming voltage magnitude drops below the second voltage level.

Claims

1. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage; and

prohibiting initiation of a programming operation if the first programming voltage is lower than a first voltage level and above a second voltage level, or if the first programming voltage is below a third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

2. The method of claim 1, further comprising:

initiating a direct memory programming operation if the first programming voltage exceeds the first voltage level; and

initiating a memory programming operation through a charge pump circuit if the first programming voltage is between the second voltage level and the third voltage level.

3. The method of claim 2, further comprising:

continuing the initiated direct memory programming operation if the first programming voltage remains greater than a second voltage level, with the first voltage level being greater than the second voltage level; and

terminating the initiated direct memory programming operation if the first programming voltage drops below the second voltage level.

4. The method of claim 1, further comprising:

continuing the initiated memory programming operation through the charge pump circuit if the first programming voltage remains greater than a lowest voltage level, with the lowest voltage level below the lower voltage level; and

terminating the initiated memory programming operation through the charge pump circuit if the first programming voltage drops below the lowest voltage level.

5. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage;

sampling the first programming voltage; and

prohibiting initiation of a programming operation if the first programming voltage is lower than a first voltage level and above a second voltage level, or if the first programming voltage is below a third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

6. The method of claim 5, further comprising:

initiating a direct memory programming operation if the first programming voltage exceeds the first voltage level;

continuing the initiated direct memory programming operation if the first programming voltage remains greater than a second voltage level, with the first voltage level being greater than the second voltage level; and

terminating the initiated direct programming operation if the first programming voltage drops below the second voltage level.

7. The method of claim 5, further comprising:

initiating a memory programming operation through a charge pump circuit if the first programming voltage is between the second voltage level and the third voltage level;

continuing the initiated memory programming operation through the charge pump circuit if the first programming voltage remains greater than a lowest voltage level, with the lowest voltage level below the lower voltage level; and

terminating the initiated memory programming operation through the charge pump circuit if the first programming voltage drops below the lowest voltage level.

8. The method of claim 7, further comprising:

activating an error indicator if the initiated memory programming operation through the charge pump circuit is terminated.

9. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage;

generating a logic signal indicative of an unacceptable first programming voltage; and

prohibiting initiation of a programming operation if the first programming voltage is lower than a first voltage level and above a second voltage level, or if the first programming voltage is below a third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

10. The method of claim 9, wherein providing a first programming voltage includes providing the first programming voltage from a source external to an integrated circuit having an array of memory cells comprising a portion of the memory system.

11. The method of claim 10, wherein the memory cells are non-volatile memory cells.

12. The method of claim 9, further comprising:

initiating a direct memory programming operation through a voltage divider circuit if the first programming voltage exceeds a first voltage level; and

initiating a memory programming operation through a charge pump circuit if the first programming voltage is within a voltage range having an upper voltage level and a lower voltage level, the upper voltage level being below the first voltage level.

13. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage;

initiating a direct memory programming operation through a voltage divider circuit if the first programming voltage exceeds a first voltage level; and

prohibiting initiation of a programming operation if the first programming voltage is lower than the first voltage level and above a second voltage level, or if the first programming voltage is below a third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

14. The method of claim 13, wherein the voltage divider circuit may produce at least one signal to initiate the direct memory programming operation if the first programming voltage exceeds the first voltage level.

15. The method of claim 13, wherein the voltage divider circuit may produce at least one signal to continue the direct memory programming operation if the first programming voltage drops below the first voltage level but remains above the second voltage level.

16. The method of claim 13, further comprising:

terminating the initiated direct programming operation if the first programming voltage drops below the second voltage level.

17. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage;

initiating a memory programming operation through a charge pump circuit if the first programming voltage is between a second voltage level and a third voltage level; and

prohibiting initiation of the memory programming operation through the charge pump circuit if the first programming voltage is lower than a first voltage level and above the second voltage level, or if the first programming voltage is below the third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

18. The method of claim 17, further comprising:

continuing the initiated programming operation through the charge pump circuit if the first programming voltage remains greater than a lowest voltage level, with the lowest voltage level below the third voltage level.

19. The method of claim 17, further comprising:

terminating the initiated programming operation through the charge pump circuit if the first programming voltage drops below a lowest voltage level lower than the third voltage level.

20. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage;

initiating a direct memory programming operation through a voltage divider circuit if the first programming voltage exceeds a first voltage level;

terminating the initiated direct programming operation if the first programming voltage drops below a third voltage level lower than the first voltage level;

activating an error indicator if the initiated direct memory programming operation is terminated; and

prohibiting initiation of the direct memory programming operation if the first programming voltage is lower than a first voltage level and above a second voltage level, or if the first programming voltage is below a third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

21. The method of claim 20, further comprising:

initiating a memory programming operation through a charge pump circuit if the first programming voltage is within a voltage range having an upper voltage level and a lower voltage level, the upper voltage level below the first voltage level.

22. The method of claim 21, further comprising:

terminating the initiated programming operation through the charge pump circuit if the first programming voltage drops below a lowest voltage level lower than the third voltage level.

23. A method of controlling the operation of a memory system which comprises an array of memory cells, the method comprising:

providing a first programming voltage; and

prohibiting initiation of a direct programming operation or a programming operation through a charge pump circuit if the first programming voltage is lower than a first voltage level and above a second voltage level, or if the first programming voltage is below a third voltage level, wherein the first voltage level is greater than the second voltage level, and wherein the second voltage level is greater than the third voltage level.

24. The method of claim 23, further comprising:

initiating the direct memory programming operation if the first programming voltage exceeds a first voltage level; and

initiating the memory programming operation through the charge pump circuit if the first programming voltage is within a voltage range having an upper voltage level and a lower voltage level, the upper voltage level below the first voltage level.