W987D6HBGX6E-TR Datasheet, PDF (22/68 Pages) Winbond – 128Mb Mobile LPSDR

W987D6HB / W987D2HB
128Mb Mobile LPSDR
7.1.21 Data Write/Output Enable, Data Mask/Output Disable Command
(DQM = L/H or LDQM, UDQM = L/H or DQM0-3=L/H)
During a Write cycle, the DQM or LDQM, UDQM or DQM0-3 signals mask write data. Each of these signals control the input buffers
per byte. During a Read cycle, the DQM or LDQM, UDQM or DQM0-3 signals control of the output buffers per byte.
I/O Org.
× 16
× 32
MASK PIN
LDQM
UDQM:
DQM0:
DQM1:
DQM2:
DQM3:
MASKED DQs
DQ0~DQ7
DQ8~DQ15
DQ0~DQ7
DQ8~DQ15
DQ16~DQ23
DQ24~DQ31
8. OPERATION
8.1 Read Operation
Issuing the Bank Activate command to the idle bank puts it into the active state. When the Read command is issued after tRCD from the
Bank Activate command, the data is read out sequentially, synchronized to the positive edges of CLK (a Burst Read operation). The
initial read data becomes available after CAS Latency from the issuing of the Read command. The CAS latency must be set in the
Mode Register at power-up. In addition, the burst length of read data and Addressing Mode must be set. Each bank is held in the active
state unless the Precharge command is issued, so that the sense amplifiers can be used as secondary cache.
When the Read with Auto Precharge command is issued, the Precharge operation is performed automatically after the Read cycle, then
the bank is switched to the idle state. This command cannot be interrupted by any other commands. Also, when the Burst Length is 1
and tRCD (min), the timing from the RAS command to the start of the Auto Precharge operation is shorter than tRAS (min). In this case,
tRAS (min) must be satisfied by extending tRCD.
When the Precharge operation is performed on a bank during a Burst Read operation, the Burst operation is terminated.
When the Burst Length is full-page, column data is repeatedly read out until the Burst Stop command or Precharge command is issued.
8.2 Write Operation
Issuing the Write command after tRCD from the Bank Activate command, the input data is latched sequentially, synchronizing with the
positive edges of CLK after the Write command (Burst Write operation). The burst length of the Write data (Burst Length) and Addressing
Mode must be set in the Mode Register at power-up.
When the Write with Auto Precharge command is issued, the Precharge operation is performed automatically after the Write cycle, then
the bank is switched to the idle state. This command cannot be interrupted by any other command for the entire burst data duration.
Also, when the Burst Length is 1 and tRCD (min), the timing from the RAS command to the start of the Auto Precharge operation is
shorter than tRAS (min). In this case, tRAS (min) must be satisfied by extending tRCD.
When the Precharge operation is performed in a bank during a Burst Write operation, the Burst operation is terminated.
When the Burst Length is full-page, the input data is repeatedly latched until the Burst Stop command or the Precharge command is
issued.
When the Burst Read and Single Write mode is selected, the write burst length is 1 regardless of the read burst length.
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Publication Release Date: Jun. 09, 2011
Revision A01-002