Patent ID: 7944744

Claim:
A method of determining values related to discharge of charge-storing memory cells in a storage device, the method comprising: in a storage device having a plurality of charge-storing memory cells including n (n≧1) groups of one or more charge-storing memory cells, performing, by a controller of the storage device, programming the charge-storing memory cells of the n groups of charge-storing memory cells, with each of the charge-storing memory cells of each of the n groups being initially programmed to a respective particular one of N (N≧2) binary states by storing therein an amount of electric charge proportional to a voltage higher than a threshold voltage corresponding to the particular binary state, whereby, over time, the respective charge-storing memory cell undergoes self discharge; determining a value related to the self-discharge undergone by the charge-storing memory cells of the n groups, the determining being performed at a given time by, (i) detecting, for each of the n groups, a respective distribution of binary states of the programmed charge-storing memory cells relative to initially programmed binary states thereof; (ii) calculating, for each of the n groups, a value representative of the respective distribution of binary states to generate calculated values; and (iii) converting the calculated values to a discharge-determining condition.