W9425G6DH 查看數據表（PDF） - Winbond

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W9425G6DH

4M × 4 BANKS × 16 BITS DDR SDRAM

Winbond 

W9425G6DH

7.2.16 Data Write Enable /Disable Command

(DM = "L/H" or LDM, UDM = "L/H")

During a Write cycle, the DM or LDM, UDM signal functions as Data Mask and can control every

word of the input data. The LDM signal controls DQ0 to DQ7 and UDM signal controls DQ8 to

DQ15.

7.3 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 with both edges of DQS (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.

When the Precharge Operation is performed on a bank during a Burst Read and operation, the Burst

operation is terminated.

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. Refer to the diagrams for Read operation.

7.4 Write Operation

Issuing the Write command after tRCD from the bank activate command. The input data is latched

sequentially, synchronizing with both edges(rising & falling) of DQS 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 Precharge operation is performed in a bank during a Burst Write operation, the Burst

operation is terminated.

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, The Write with Auto-

precharge command cannot be interrupted by any other command for the entire burst data duration.

Refer to the diagrams for Write operation.

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Publication Release Date:Nov. 20, 2007

Revision A7

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