Datasheet

bank
Figure 10 — Active Command
Figure 11 — Bank Activation Command Cycle
7.5. Read
The READ command (see Figure 12) is used to initiate a burst read access to an active row, with a burst length as set in the
Mode Register. BA0 and BA1 select the bank, and the address inputs select the starting column location. The value of A10
determines whether or not Auto Precharge is used. If Auto Precharge is selected, the row being accessed will be precharged at
the end of the read burst; if Auto Precharge is not selected, the row will remain open for subsequent accesses.
The basic Read timing parameters for DQs are
shown in Figure 13; they apply to all Read operations.
During Read bursts, DQS is driven by the LPDDR SDRAM along with the output data. The initial Low state of the DQS is known
as the read preamble; the Low state coincident with last data-out element is known as the read postamble. The first data-out
element is edge aligned with the first rising edge of DQS and the successive data-out elements are edge aligned to successive
edges of DQS. This is shown in Figure 14 with a CAS latency of 2 and 3.
Upon completion of a read burst, assuming no other READ command has been initiated, the DQs will go to High-Z.
AS4C16M16MD1
256Mb MOBILE DDR SDRAM
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