W948D6FBHX5E-TR Datasheet, PDF (15/60 Pages) Winbond – 256Mb Mobile LPDDR

W948D6FB / W948D2FB
256Mb Mobile LPDDR
Notes:
1. For a burst length of two, A1-An selects the two data element block; A0 selects the first access within the block.
2. For a burst length of four, A2-An selects the four data element block; A0-A1 selects the first access within the block.
3. For a burst length of eight, A3-An selects the eight data element block; A0-A2 selects the first access within the block.
4. For the optional burst length of sixteen, A4-An selects the sixteen data element block; A0-A3 selects the first access within the
block.
5. Whenever a boundary of the block is reached within a given sequence, the following access wraps within the block.
When a READ or WRITE command is issued, a block of columns equal to the burst length is effectively selected. All accesses
for that burst take place within the block, meaning that the burst will wrap within the block if a boundary is reached.
The block is uniquely selected by A1-An when the burst length is set to two, by A2-An when the burst length is set to 4, by A3-
An when the burst length is set to 8 and A4-An when the burst length is set to 16(where An is the most significant column
address bit for a given configuration). The remaining (least significant) address bit(s) is (are) used to select the starting location
within the block. The programmed burst length applies to both read and write bursts.
6.4 Burst Type
Accesses within a given burst may be programmed to be either sequential or interleaved; this is referred to as the
burst type and is selected via bit A3. The ordering of accesses within a burst is determined by the burst length, the
burst type and the starting column address, as shown in the previous table.
6.5 Read Latency
The READ latency is the delay between the registration of a READ command and the availability of the first piece of
output data. The latency should be set to 2 or 3 clocks.
If a READ command is registered at a clock edge n and the latency is 3 clocks, the first data element will be valid at
n + 2 tCK + tAC. If a READ command is registered at a clock edge n and the latency is 2 clocks, the first data
element will be valid at n + tCK + tAC.
6.6 Extended Mode Register Description
The Extended Mode Register controls functions beyond those controlled by the Mode Register; these additional
functions include output drive strength selection and Partial Array Self Refresh (PASR). PASR is effective in Self
Refresh mode only.
The Extended Mode Register is programmed via the MODE REGISTER SET command (with BA1=1 and BA0=0)
and will retain the stored information until it is reprogrammed, the device is put in Deep Power Down mode, or the
device loses power.
The Extended Mode Register must be loaded when all banks are idle and no bursts are in progress, and the
controller must wait the specified time tMRD before initiating any subsequent operation. Violating either of these
requirements will result in unspecified operation.
Address bits A0-A2 specify PASR, A5-A7 the Driver Strength. A logic 0 should be programmed to all the undefined
addresses bits to ensure future compatibility.
Reserved states should not be used, as unknown operation or incompatibility with future versions may result.
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Publication Release Date : Oct, 15, 2012
Revision : A01-004