Flash memory device configurable to provide read only memory functionality
View Patent ↗The disclosed embodiments comprise a flash memory device that can be configured to operate as a read only memory device. In some embodiments, the flash memory device can be configured into a flash memory portion and a read only memory portion.
1. A non-volatile memory device comprising:
an array of flash memory cells, the array comprising a first set of rows of flash memory cells and a second set of rows of flash memory cells;
a first set of decoders configured to enable the first set of rows of flash memory cells to be erased and programmed; and
a second set of decoders configured to prevent the second set of rows of flash memory cells from being erased and programmed;
wherein the first set of decoders is responsive to a first set of bits stored in a control portion of the array.
2. The non-volatile memory device of claim 1 , wherein a response to the first set of bits is stored in a latch in the first set of decoders.
3. The non-volatile memory device of claim 1 , wherein the second set of decoders is responsive to a second set of bits stored in the control portion of the array.
4. The non-volatile memory device of claim 3 , wherein a response to the second set of bits is stored in a latch in the second set of decoders.
5. The non-volatile memory device of claim 3 , wherein the control portion contains one or more bits that indicate whether the control portion can be erased and programmed.
6. The non-volatile memory device of claim 5 , wherein the first set of decoders sets voltages for an erase gate, a coupling gate, and a source line for the first set of rows of flash memory cells.
7. The non-volatile memory device of claim 6 , wherein the second set of decoders sets voltages for an erase gate, a coupling gate, and a source line for the second set of rows of flash memory cells.
8. The non-volatile memory device of claim 3 , wherein the first set of bits and the second set of bits are read from the control portion when the non-volatile memory device is powered up.
9. The non-volatile memory device of claim 3 , wherein some of the first set of bits and the second set of bits are read from the control portion when an erase or program command is received.
10. The non-volatile memory device of claim 3 , wherein the first set of bits and the second set of bits are read from the control portion after the control portion is programmed.
11. A non-volatile memory device comprising:
an array of flash memory cells, the array comprising a first set of rows of flash memory cells and a second set of rows of flash memory cells;
a first set of decoders configured to enable the first set of rows of flash memory cells to be erased and programmed;
a second set of decoders configured to prevent the second set of rows of flash memory cells from being erased and programmed; and
a control portion in the array and a control portion sector decoder associated with the control portion.
12. The non-volatile memory device of claim 11 , wherein the control portion sector decoder comprises a latch to disable the erasing and programming of the control portion.
13. A method of operating a non-volatile memory device comprising an array of flash memory cells, the array comprising a first set of rows of flash memory cells and a second set of rows of flash memory cells, the method comprising:
receiving, by a first set of decoders, a first set of bits from a control portion of the array;
receiving, by a second set of decoders, a second set of bits from the control portion of the array;
enabling, by the first set of decoders, the first set of rows of flash memory cells to be erased and programmed; and
disabling, by the second set of decoders, the second set of rows of flash memory cells from being erased and programmed.
14. The method of claim 13 , wherein the control portion contains one or more bits that indicate whether the control portion can be erased and programmed.
15. The method of claim 13 , further comprising:
setting, by the first set of decoders, voltages for an erase gate, a coupling gate, and a source line for the first set of rows of flash memory cells.
16. The method of claim 15 , further comprising:
setting, by the second set of decoders, voltages for an erase gate, a coupling gate, and a source line for the second set of rows of flash memory cells.
17. The method of claim 13 , further comprising:
reading the first set of bits and the second set of bits from the control portion when the non-volatile memory device is powered up.
18. The method of claim 13 , further comprising:
reading some of the first set of bits and the second set of bits from the control portion when an erase or program command is received.
19. The method of claim 13 , further comprising:
reading the first set of bits and the second set of bits from the control portion after the control portion is programmed.
20. The method of claim 13 , wherein each of the flash memory cells is a non-volatile split gate memory cell.
21. The method of claim 13 , wherein the second set of rows of flash memory cells is one time programmable.
22. The method of claim 21 , wherein an OTP bit in an OTP sector in the array enables the second set of rows of flash memory cells to be one time programmable.
23. The method of claim 13 , wherein the number of rows in the second set of rows of memory array is variable.
24. A non-volatile memory device comprising:
an array of flash memory cells, the array comprising a first set of rows of flash memory cells and a second set of rows of flash memory cells;
a first set of decoders configured to enable the first set of rows of flash memory cells to be erased and programmed in response to a first set of bits stored in a control portion of the array; and
a second set of decoders configured to prevent the second set of rows of flash memory cells from being erased and programmed in response to a second set of bits stored in the control portion of the array; and
a security circuit for enabling the control portion to be erased and programmed when a first set of data is received that matches a second set of data stored in the control portion.
25. The non-volatile memory device of claim 24 , wherein the first set of decoders sets voltages for an erase gate, a coupling gate, and a source line for the first set of rows of flash memory cells.
26. The non-volatile memory device of claim 25 , wherein the second set of decoders sets voltages for an erase gate, a coupling gate, and a source line for the second set of rows of flash memory cells.
27. The non-volatile memory device of claim 24 , wherein the first set of bits and the second set of bits are read from the control portion when the non-volatile memory device is powered up.
28. The non-volatile memory device of claim 24 , wherein some of the first set of bits and the second set of bits are read from the control portion when an erase or program command is received.
29. The non-volatile memory device of claim 24 , wherein the first set of bits and the second set of bits are read from the control portion after the control portion is programmed.
30. The non-volatile memory device of claim 24 , wherein each of the flash memory cells is a non-volatile split gate memory cell.
31. A method of operating a non-volatile memory device comprising an array of flash memory cells, the array comprising a first set of rows of flash memory cells and a second set of rows of flash memory cells, the method comprising:
receiving, by a first set of decoders, a first set of bits from a control portion of the array;
receiving, by a second set of decoders, a second set of bits from the control portion of the array;
enabling, by the first set of decoders, the first set of rows of flash memory cells to be erased and programmed;
disabling, by the second set of decoders, the second set of rows of flash memory cells from being erased and programmed; and
receiving, by a security circuit, a first set of data and enabling the control portion to be erased and programmed if the first set of data matches a second set of data stored in the control portion.
32. The method of claim 31 , further comprising:
setting, by the first set of decoders, voltages for an erase gate, a coupling gate, and a source line for the first set of rows of flash memory cells.
33. The method of claim 32 , further comprising:
setting, by the second set of decoders, voltages for an erase gate, a coupling gate, and a source line for the second set of rows of flash memory cells.
34. The method of claim 31 , further comprising:
reading the first set of bits and the second set of bits from the control portion when the non-volatile memory device is powered up.
35. The method of claim 31 , further comprising:
reading some of the first set of bits and the second set of bits from the control portion when the an erase or program command is received.
36. The method of claim 31 , further comprising:
reading the first set of bits and the second set of bits from the control portion after the control portion is programmed.
37. The method of claim 31 , wherein each of the flash memory cells is a non-volatile split gate memory cell.
38. The method of claim 31 , wherein the second set of rows of flash memory cells is one time programmable.
39. The method of claim 38 wherein an OTP bit in an OTP sector in the array enables the second set of rows of flash memory cells to be one time programmable.
40. The method of claim 31 , wherein the number of rows in the second set of rows of memory array is variable.