Flash memory organization

• US 8,245,112 B2
• Filed: 06/04/2009
• Issued: 08/14/2012
• Est. Priority Date: 06/04/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Hicken, Michael, Dell, Martin
• Primary Examiner(s): Chase, Shelly A
• Application Number:
  US12/478,013
• Publication Number:
  US 20100313100A1
• Time in Patent Office: 1,167 Days
• Field of Search: 714763-764, 714/766, 714/777, 714/782
• US Class Current: 714/766
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/403 Error protection encoding, e.g. using parity or ECC codes
• CPC Class Codes: G06F 2212/7207 management of metadata or control data
• CPC Class Codes: H03M 13/15 Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes H03M13/17 takes precedence
• CPC Class Codes: H03M 13/152 Bose-Chaudhuri-Hocquenghem [BCH] codes

Abstract

A flash-memory system is organized into a plurality of blocks and a plurality of pages in each block, each page having 2^N data locations and K spare locations. At least one page in the memory has 2^M−1 user data sectors and each sector has 2^N-M+L locations therein. Error-correction code (ECC) data related to the user data is calculated and stored in at least the 2^M user data locations unused by the 2^M−1 user data sectors. Because L is at least 1 but less than 2^N-M (N>M), at least a portion of one user data sector is stored in the spare memory locations. Additional locations in each page are available to allow for the ECC data to have additional redundancy bits added per sector, thereby making the flash memory system more robust and reliable.

Claims

1. A flash memory system having a plurality of pages, each page having 2^N data locations and K spare locations, and at least one page comprising:

2^M−

1 or less user data sectors, each sector having 2^N-M+L locations therein; and

error-correction code (ECC) data related to the user data and stored in at least the 2^M user data locations unused by the 2^M−

1 user data sectors;

wherein M, N, L, and K are positive integers, N>

M, M≧

1, 1≦

L<

2^N-M, and wherein at least a portion of one user data sector is stored in the spare locations.

2. The memory system of claim 1, wherein the ECC data comprises 2^M−

1 ECC data segments, each segment corresponding to one of the user data sectors.

3. The memory system of claim 2, wherein at least a portion of an ECC data segment is stored in the spare locations.

4. The memory system of claim 2, wherein the ECC data segments are stored adjacent to the corresponding user data sectors.

5. The memory system of claim 1, wherein the ECC data is calculated using a 1-lamming-class code.

6. The memory system of claim 5, wherein the 1-lamming-class code is a BCH code having at least 392 bits of redundancy per user data sector.

7. The memory system of claim 1, wherein the memory is arranged in bytes, and L=2^P, where P is a positive integer.

8. The memory system of claim 7, wherein M=3, N=12, P=3 or 4, and K=224.

9. The memory system of claim 7, wherein M=4, N=13, P=3, 4, or 5, and K=520.

10. A method comprising:

providing a flash memory system having a plurality of pages, each page having 2^N data locations and K spare locations, at least one page storing no more than 2^M−

1 user data sectors therein;

storing user data in at least one of the 2^M−

1 user data sectors, each of the user data sectors having 2^N-M+1, locations therein;

calculating error-correction code (ECC) data related to the stored user data; and

storing the ECC data in at least the 2^M user data locations unused by the 2^M−

1 user data sectors;

wherein M, N, L, and K are positive integers, N>

M, M≧

1, 1≦

L<

2^N-M, and wherein at least a portion of one user data sector is stored in the spare locations.

11. The method of claim 10, further comprising the step of reading at least one of the 2^M−

1 user data sectors and corresponding ECC data.

12. The method of claim 11, further comprising the step of checking and, if required, correcting the read user data.

13. The method of claim 10, wherein at least a portion of an ECC data segment is stored in the spare locations.

14. The method of claim 10, wherein the ECC data are configured into 2^M−

1 segments, each segment corresponding to one of the user data sectors.

15. The method of claim 10, wherein the ECC data are calculated using a Hamming-class code.

16. The method of claim 15, wherein the Hamming-class code is a BCH code having at least 392 bits of redundancy per user data sector.

17. The method of claim 10, wherein the memory is arranged in bytes, and L=2^P, where P is a positive integer.

18. The method of claim 17, wherein M=3, N=12, P=3 or 4, and K=224.

19. The method of claim 17, wherein M=4, N=13, P=3, 4, or 5, and K=520.

20. A method comprising:

providing a flash memory system having a plurality of pages, each page having 2^N data locations and K spare locations, at least one page storing no more than 2^M−

1 user data sectors therein;

storing user data in at least one of the 2^M−

1 user data sectors, each of the user data sectors having 2_N-M+L locations therein;

calculating error-correction code (ECC) data related to the stored user data;

reading at least one of the 2^M−

1 user data sectors and corresponding ECC data; and

checking and, if required, correcting the read user data;

storing the ECC data in at least the 2^M user data locations unused by the 2^M−

1 user data sectors;

wherein M, N, L, and K are positive integers, N>

M, M≧

1, 1≦

L<

2^N-M, and wherein at least a portion of one user data sector is stored in the spare locations, and wherein the ECC data calculated using a BCH code having at least 392 bits of redundancy per user data sector.

21. The method of claim 20, wherein the memory is arranged in bytes, M=3, N=12, L=2^P, P=3 or 4, and K=224.