HM5225165B/HM5225805B/HM5225405B-75/A6/B6
DQM Control
The DQM mask the DQ data. The DQMU and DQML mask the upper and lower bytes of the DQ data,
respectively. The timing of DQMU/DQML is different during reading and writing.
Reading: When data is read, the output buffer can be controlled by DQM, DQMU/DQML. By setting
DQM, DQMU/DQML to Low, the output buffer becomes Low-Z, enabling data output. By setting DQM,
DQMU/DQML to High, the output buffer becomes High-Z, and the corresponding data is not output.
However, internal reading operations continue. The latency of DQM, DQMU/DQML during reading is 2
clocks.
Writing: Input data can be masked by DQM, DQMU/DQML. By setting DQM, DQMU/DQML to Low,
data can be written. In addition, when DQM, DQMU/DQML is set to High, the corresponding data is not
written, and the previous data is held. The latency of DQM, DQMU/DQML during writing is 0 clock.
Reading
CLK
DQM,
DQMU/DQML
High-Z
DQ (output)
out 0
l
out 1
out 3
= 2 Latency
DOD
Writing
CLK
DQM,
DQMU/DQML
DQ (input)
in 3
in 0
in 1
l
= 0 Latency
DID
Data Sheet E0082H10
39
ELPIDA [ ELPIDA MEMORY ]
