Patent attributes
A Flash memory system and a method for data management using the embodiments of the invention use special test cells with Early Degradation Detection (EDD) circuitry instead of using the actual user-data storage cells are described. The Flash memory test cells can be made to serve as a “canary in a coal mine” by being made more sensitive than the standard cells by using experimentally determined sensitive write VT and variable read VT. Techniques for early degradation detection (EDD) in Flash memories measure the dispersion of the threshold voltages (VT's), of a set (e.g. page) of NAND Flash memory cells during read operations. In an embodiment of the invention the time-to-completion (TTC) values for the read operation for the memory cells are used as a proxy for dispersion of the threshold voltages (VT's). A Dispersion Analyzer determines the dispersion of the set of TTC values.
