Semiconductor memory device including an on-die ecc engine

Abstract

A semiconductor memory device includes a memory cell array, an on-die error correction code (ECC) engine and a control logic circuit. The on-die ECC engine includes a first latch and a second latch. The control logic circuit sets the semiconductor memory device to a test mode in response to a first mode register set command. The on-die ECC engine, in the test mode, cuts off a connection with the memory cell array, receives a test data, stores the test data in the first latch, performs an ECC decoding on the test data stored in the first latch and a test parity data, stored in the second latch in response to a read command and provides an external device with a severity signal indicating whether the test data and the test parity data includes at least one error bit and the at least one error bit is correctable.