Read disturb detection based on dynamic bit error rate estimation

A method comprising:

• performing a write operation to write data to a first location in a non-volatile memory (NVM);
• counting each of a plurality of read operations applied to the first location after the write operation to obtain a read disturb count (RDC) value;
• accumulating a first bit error statistic (BES) value indicative of a rate of read errors obtained during the plurality of read operations;
• setting a flag value responsive to the RDC value reaching a first threshold;
• reducing the RDC value responsive to the setting of the flag value and responsive to a comparison of the first BES value with a second threshold;
• incrementing the reduced RDC value responsive to each of a plurality of additional read operations applied to the first location after the setting of the flag value;
• accumulating a second BES value indicative of a rate of read errors obtained during the plurality of additional read operations;
• and
• relocating the data from the first location to a second location in the NVM responsive to each of the RDC value subsequently reaching the first threshold a second time, the second BES value exceeding a third threshold less than the second threshold, and the setting of the flag value.

An apparatus comprising:

• a non-volatile memory (NVM);
• a read/write circuit configured to write data to and read data from the NVM;
• and
• a read data disturb (RDD) manager circuit configured to:
• detect a presence of read disturbed data in the NVM by counting a number of read operations applied to a first location in the NVM to maintain an updated read disturb count (RDC) value, by reducing the RDC value to a reduced level responsive to the RDC value reaching a predetermined threshold level and responsive to a bit error statistic (BES) value indicating an acceptable rate of read errors occurred during the application of the number of read operations to the first location, by counting additional read operations applied to the first location after the RDC value has been reduced to increase the RDC value from the reduced level, and by determining the BES value indicates an unacceptable rate of read errors occurred during the application of the additional read operations as the RDC value reaches the predetermined threshold level a second time;
• and
• relocate data from the first location to a second location in the NVM responsive to the detection of the presence of the read disturbed data, the RDD manager circuit comprising a counter circuit configured to count a total number of read operations and a buffer memory which accumulates the RDC value as a multi-bit value, the RDD manager further configured to reduce the RDC value responsive to the toggling of a most significant bit (MSB) value location in the buffer memory by the RDC value.

An apparatus comprising:

• a non-volatile memory (NVM);
• a read/write circuit configured to write data to and read data from the NVM;
• and
• a read data disturb (RDD) manager circuit configured to:
• write data to a first location in the NVM;
• count a number of read operations applied to the first location in the NVM to maintain an updated read disturb count (RDC) value;
• reduce the RDC value to a reduced level responsive to the RDC value reaching a predetermined threshold level and responsive to a first bit error statistic (BES) value indicating an acceptable rate of read errors occurred during the application of the number of read operations to the first location;
• count additional read operations applied to the first location after the RDC value has been reduced;
• determine an updated second BES value by applying a derating factor to smooth out incremental changes in the first BES value from localized increases in bit errors;
• and
• relocate the data from the first location to the second location responsive to the RDC value reaching the predetermined threshold level a second time and the updated second BES value indicating an unacceptable rate of read errors occurred during the application of the additional read operations.