EDS2504ACTA/08ACTA/16ACTA, EDS2504APTA/08APTA/16APTA
DQM Control
The DQM mask the DQ data. The UDQM and LDQM mask the upper and lower bytes of the DQ data, respectively.
The timing of UDQM/LDQM is different during reading and writing.
Reading
When data is read, the output buffer can be controlled by DQM. By setting DQM to Low, the output buffer becomes
Low-Z, enabling data output. By setting DQM to High, the output buffer becomes High-Z, and the corresponding
data is not output. However, internal reading operations continue. The latency of DQM during reading is 2 clocks.
Writing
Input data can be masked by DQM. By setting DQM to Low, data can be written. In addition, when DQM is set to
High, the corresponding data is not written, and the previous data is held. The latency of DQM during writing is 0
clock.
CLK
DQM
High-Z
DQ
out 0
out 1
out 3
lDOD = 2 Latency
Reading
CLK
DQM
DQ
in 3
in 0
in 1
lDID = 0 Latency
Writing
Data Sheet E0110E30 (Ver. 3.0)
40
ELPIDA [ ELPIDA MEMORY ]
