IS42S32400E-7BL ISSI, Integrated Silicon Solution Inc, IS42S32400E-7BL Datasheet - Page 25

• Manufacturer Part Number: IS42S32400E-7BL
• Description: IC SDRAM 128MBIT 143MHZ 90FBGA
• Manufacturer: ISSI, Integrated Silicon Solution Inc

Specifications of IS42S32400E-7BL

• Format - Memory: RAM
• Memory Type: SDRAM
• Memory Size: 128M (4Mx32)
• Speed: 143MHz
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 90-FBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 706-1065; IS42S32400E-7BL

CAS LATENCY
IS42S32400E
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 CAS
Latency diagrams. The Allowable Operating Frequency
table indicates the operating frequencies at which each
CAS latency setting can be used.
Reserved states should not be used as unknown operation
or incompatibility with future versions may result.
Integrated Silicon Solution, Inc. - www.issi.com
Rev. 00C
08/01/08
COMMAND
COMMAND
CLK
CLK
DQ
DQ
READ
READ
T0
T0
CAS Latency - 2
NOP
NOP
CAS Latency - 3
T1
T1
t
LZ
t
AC
CAS Latency
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 be-
cause 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.
Speed
NOP
NOP
Allowable Operating Frequency (MHz)
T2
T2
-6
-7
D
OUT
t
t
OH
LZ
t
AC
NOP
T3
T3
CAS Latency = 2
D
DON'T CARE
UNDEFINED
OUT
t
OH
125
100
T4
CAS Latency = 3
166
143
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