MT48H32M32LFB5-6 IT:B Micron, MT48H32M32LFB5-6 IT:B Datasheet - Page 45

• Manufacturer Part Number: MT48H32M32LFB5-6 IT:B
• Manufacturer: Micron

Figure 16: Random READ Accesses
PDF: 09005aef8404b23d
y68m_mobile_lpsdr.pdf – Rev. D 1/11 EN
Note:
Command
Command
Data from any READ burst can be truncated with a subsequent WRITE command, and
data from a fixed-length READ burst can be followed immediately by data from a
WRITE command (subject to bus turnaround limitations). The WRITE burst can be ini-
tiated on the clock edge immediately following the last (or last desired) data element
from the READ burst, provided that I/O contention can be avoided. In a given system
design, there is a possibility that the device driving the input data will go Low-Z before
the DQ go High-Z. In this case, at least a single-cycle delay should occur between the
last read data and the WRITE command.
The DQM input is used to avoid I/O contention, as shown in Figure 17 (page 46) and
Figure 18 (page 47). The DQM signal must be asserted (HIGH) at least two clocks prior
to the WRITE command (DQM latency is two clocks for output buffers) to suppress da-
ta-out from the READ. After the WRITE command is registered, the DQ will go to High-Z
(or remain High-Z), regardless of the state of the DQM signal, provided the DQM was
active on the clock just prior to the WRITE command that truncated the READ com-
mand. If not, the second WRITE will be an invalid WRITE. For example, if DQM was
LOW during T4, then the WRITEs at T5 and T7 would be valid, and the WRITE at T6
would be invalid.
Address
Address
1. Each READ command can be issued to any bank. DQM is LOW.
CLK
CLK
DQ
DQ
T0
T0
READ
Bank,
READ
Bank,
Col n
Col n
CL = 2
T1
T1
READ
READ
Bank,
Bank,
Col a
Col a
CL = 3
45
T2
T2
Bank,
Bank,
READ
READ
Col x
Col x
D
OUT
n
T3
T3
READ
Bank,
Col m
READ
Bank,
Col m
Micron Technology, Inc. reserves the right to change products or specifications without notice.
D
D
OUT
OUT
a
n
1Gb: x32 Mobile LPSDR SDRAM
T4
T4
NOP
NOP
D
D
OUT
OUT
x
a
T5
T5
NOP
NOP
D
D
OUT
m
OUT
x
© 2010 Micron Technology, Inc. All rights reserved.
T6
Don’t Care
READ Operation
NOP
D
OUT
m