W989D6DB Datasheet, PDF (15/64 Pages) Winbond – Standard Self Refresh Mode

W989D6DB / W989D2DB
7.1.4 Bank Activate Command
( RAS = L, CAS = H, WE = H, BA0, BA1 = Bank, A0~An = Row Address)
The Bank Activate command activates the bank designated by the BA (Bank Select) signal.
Row addresses are latched on A0~An when this command is issued and the cell data is read out to the sense
amplifiers. The maximum time that each bank can be held in the active state is specified as tRAS (max).
7.1.5 Bank Precharge Command
( RAS = L, CAS = H, WE = L, BA0, BA1 = Bank, A10 = L)
The Bank Precharge command is used to close (or precharge) the bank that is activated. Using this command,
systems can designated the bank to be closed by specifying the BA address bit setting in the command set. A
Precharge command can be used to precharge each bank separately (Bank Precharge) or all four banks
simultaneously (Precharge All). After the Bank Precharge command is issued, any one bank can close, and the
closed bank transitions from the active state to the idle state. To re-activate the closed bank, a system has to wait
the minimum tRP delay after issuing the Precharge command before issuing the Active Command for the device
to complete the Precharge operation.
7.1.6 Precharge All Command
( RAS = L, CAS = H, WE = L, BA0, BA1 = Don’t care, A10 = H)
The Precharge All command is used to precharge all banks simultaneously. After this command is issued, all four
banks close and transition from the active state to the idle state.
7.1.7 Write Command
( RAS = H, CAS = L, WE = L, BA0, BA1 = Bank, A10 = L)
The Write command initiates a Write operation to the bank selected by BA0 and BA1 address inputs. The write
data is latched at the positive edge of CLK. Users should preprogram the length of the write data (Burst Length)
and the column access sequence (Addressing Mode) by setting the Mode Resister at power-up prior to using the
Write command.
7.1.8 Write with Auto Precharge Command
( RAS = H, CAS = L, WE = L, BA0, BA1 = Bank, A10 = H)
The Write with Auto Precharge command performs the Precharge operation automatically after the Write
operation. The internal precharge starts in the cycles immediately following the cycle in which the last data is
written independent of CAS Latency.
7.1.9 Read Command
( RAS = H, CAS = L, WE = H, BA0, BA1 = Bank, A10 = L)
The Read command performs a Read operation to the bank designated by BA0-1. The read data is issued
sequentially synchronized to the positive edges of CLK. The length of read data (Burst Length), Addressing Mode
and CAS Latency (access time from CAS command in a clock cycle) must be programmed in the Mode Register
at power-up prior to the Write operation.
7.1.10 Read with Auto Precharge Command
( RAS = H, CAS = L, WE = H, BA0, BA1 = Bank, A10 = H)
The Read with Auto Precharge command automatically performs the Precharge operation after the Read
operation. When the CAS Latency = 3, the internal precharge starts two cycles before the last data is output.
When the CAS Latency = 2, the internal precharge starts one cycle before the last data is output.
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Publication Release Date: Mar. 19, 2014
Revision: A01-001