| 摘要 |
PURPOSE:To make it possible to measure a refresh interval at a self-refresh time, by judging the sum of the number of refreshes by the writing and reading thereof from/to a refresh address using counter check function. CONSTITUTION:At the beginning, data 0 is written in all of memory cells. Next, (x) data 1 are continuously written using counter check function as the second operation. In the third, pulse refresh is performed 256-x-y times to increase one refresh address. In the fourth, self-refresh operation is performed for an arbitrary time and, in the fifth, counter check function is used to once read data 1. By this method, if the number of times of self-refreshes performed in the fourth time are between y-times and y+x-z times, pass is judged. Therefore, in this testing method, it can be judged whether the refresh interval at the time of self-refresh fulls within a set condition range by one test and the measurement thereof is enabled.
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