Adaptive Refresh Apparatus and Method

Abstract

The invention discloses an adaptive refreshing device and method. The device and method are suitable for a flash memory array. The flash memory array comprises a first array area, a first monitoring line is located at a side of the memory array in the first array area, the first array area comprises a selective block and a first non-selective block, and the first monitoring line comprises multiple first monitoring units pre-written in a first logic level. The adaptive refreshing device comprises a detection unit, a control unit and a refreshing unit. The detection unit is used for detecting if one of the first monitoring units is transferred to a second logic level from the first logic level. When the detection unit finds that one of the first monitoring units is located in the second logic level, the control unit sets a first refreshing label. According to the first refreshing label, the first monitoring unit in the second logic level is written in the first logic level and the first non-selective block is refreshed, and after refreshing, the first refreshing label is removed. Compared with the prior art, the device and method can reduce erasure time.

Description

Technical field [0001] The present invention relates to a flash memory refresh method, in particular to an adaptive refresh device and method of a flash memory. Background technique [0002] Flash memory is a special type of non-volatile memory, and its logic data is stored in memory cells. Generally, flash memory places memory cells in rows and columns, where each column represents a bit line of data. The flash memory uses voltage to be applied to the memory cell to set its threshold voltage, and the level of the threshold voltage represents the data stored in the memory cell. By applying different voltages to the gates of selected memory cells, the threshold voltage levels of the memory cells after writing, erasing, and over-erased can be verified. When the voltage applied to the gate is sufficient to exceed the threshold voltage, the transistor turns on and generates current; on the contrary, when the voltage applied to the gate cannot exceed the threshold voltage, the trans...

AI Technical Summary

Problems solved by technology

However, the actions during refresh are usually performed for all non-selected blocks, which will lengthen the operation time, and also cause write disturbance to the memory cells in the surrounding rows and columns during the refresh process, thereby changing their memory cells. Threshold voltage

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