| 摘要 |
An ECC circuit has an error correction function of N (N is a natural number) bits for output data of a memory cell array. A BIST circuit reads background data out of test target addresses, and writes/reads inverted data of the background data in at least a part of the testing target addresses. An N+1 bit error detection circuit outputs a signal indicative of test NG (defective product) when a total of error bit numbers n 1 and n 2 detected by the ECC circuit during first and second readings exceeds N.
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