N16D1633LPA
Advance Information
NanoAmp Solutions, Inc.
Burst Length
Read and write accesses to the SDRAM are burst oriented, with the burst length being programmable, as shown in
Figure 1. The burst length determines the maximum number of column locations that can be accessed for a given
READ or WRITE command. Burst lengths of 1, 2, 4 or 8 locations are available for both the sequential and the
interleaved burst types, and a full-page burst is available for the sequential type. The full-page burst is used in
conjunction with the BURST TERMINATE command to generate arbitrary burst lengths.
Reserved states should not be used, as unknown operation or incompatibility with future versions may result. 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 this block, meaning that the burst will wrap within the block if a boundary is reached. The
block is uniquely selected by A1-A7 when the burst length is set to two; by A2-A7 when the burst length is set to four;
and by A3-A7 when the burst length is set to eight. The remaining (least significant) address bit(s) is (are) used to
select the starting location within the block. Full-page bursts wrap within the page if the boundary is reached.
Bank(Row) Active
The Bank Active command is used to activate a row in a specified bank of the device. This command is initiated by
activating /CS, /RAS and deasserting /CAS, /WE at the positive edge of the clock. The value on the A11 selects the
bank, and the value on the A0-A10 selects the row. This row remains active for column access until a precharge
command is issued to that bank. Read and write operations can only be initiated on this activated bank after the
minimum tRCD time is passed from the activate command.
Read
The READ command is used to initiate the burst read of data. This command is initiated by activating /CS, /CAS, and
deasserting /WE, /RAS at the positive edge of the clock. A11 input select the bank, A0-A7 address inputs select the
starting column location. The value on input 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 active for subsequent accesses. The length of burst and the CAS latency will be determined by the
values programmed during the MRS command.
Write
The WRITE command is used to initiate the burst write of data. This command is initiated by activating /CS, /CAS, /WE
and deasserting /RAS at the positive edge of the clock. A11 input select the bank, A0-A7 address inputs select the
starting column location. The value on input 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 WRITE burst; if Auto Precharge is not selected,
the row will remain active for subsequent accesses.
Stock No. 23395- Rev I 5/05
10
The specifications of this device are subject to change without notice. For latest documentation see http://www.nanoamp.com.
NANOAMP [ NANOAMP SOLUTIONS, INC. ]
