参数资料
型号: W989D2CBJX6E
厂商: WINBOND ELECTRONICS CORP
元件分类: DRAM
英文描述: 16M X 32 DDR DRAM, 5.4 ns, PBGA90
封装: 8 X 13 MM, 0.80 MM PITCH, HALOGEN FREE AND LEAD FREE, VFBGA-90
文件页数: 14/67页
文件大小: 1469K
代理商: W989D2CBJX6E
W989D6CB / W989D2CB
512Mb Mobile LPSDR
Publication Release Date: Jun, 27, 2011
- 21 -
Revision A01-004
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.
MASK PIN
MASKED DQs
×16
LDQM
DQ0~DQ7
UDQM:
DQ8~DQ15
×32
DQM0:
DQ0~DQ7
DQM1:
DQ8~DQ15
DQM2:
DQ16~DQ23
DQM3:
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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