N16D1633LPA
Advance Information
NanoAmp Solutions, Inc.
CAS Latency
The CAS latency is the delay, in clock cycles, between the registration of a READ command and the availability of the
first piece of output data. The latency can be set to two or three clocks. If a READ command is registered at clock edge
n, and the latency is m clocks, the data will be available by clock edge n + m. The DQs will start driving as a result of
the clock edge one cycle earlier (n + m - 1), and provided that the relevant access times are met, the data will be valid
by clock edge n + m. For example, assuming that the clock cycle time is such that all relevant access times are met, if
a READ command is registered at T0 and the latency is programmed to two clocks, the DQs will start driving after T1
and the data will be valid by T2, as shown in Figure 2. Reserved states should not be used as unknown operation or
incompatibility with future versions may result.
Figure 7: CAS Latency
T0
T1
T2
T3
CLK
COMMAND
READ
NOP
NOP
tOH
Dout
tLZ
DQ
tAC
CAS Latency=2
T0
T1
T2
T3
T4
CLK
COMMAND
READ
NOP
NOP
NOP
tOH
tLZ
DQ
Dout
tAC
CAS Latency=3
DON’T CARE
UNDEFINED
Operating Mode
The normal operating mode is selected by setting M7 and M8 to zero; the other combinations of values for M7 and M8
are reserved for future use and/or test modes. The programmed burst length applies to both READ and WRITE bursts.
Test modes and reserved states should not be used because unknown operation or incompatibility with future versions
may result.
Write Burst Mode
When M9 = 0, the burst length programmed via M0-M2 applies to both READ and WRITE bursts; when M9 = 1, the
programmed burst length applies to READ bursts, but write accesses are single-location (nonburst) accesses.
Stock No. 23395- Rev I 5/05
11
The specifications of this device are subject to change without notice. For latest documentation see http://www.nanoamp.com.
NANOAMP [ NANOAMP SOLUTIONS, INC. ]
