IS42S83200B,
IS42S16160B
ISSI
®
DEVICE OVERVIEW
The 256Mb SDRAM is a high speed CMOS, dynamic
random-access memory designed to operate in 3.3V V
DD
and 3.3V V
DDQ
memory systems containing 268,435,456
bits. Internally configured as a quad-bank DRAM with a
synchronous interface. Each 67,108,864-bit bank is orga-
nized as 8,192 rows by 512 columns by 16 bits or 8,192 rows
by 1,024 columns by 8 bits.
The 256Mb SDRAM includes an AUTO REFRESH MODE,
and a power-saving, power-down mode. All signals are
registered on the positive edge of the clock signal, CLK. All
inputs and outputs are LVTTL compatible.
The 256Mb SDRAM has the ability to synchronously burst
data at a high data rate with automatic column-address
generation, the ability to interleave between internal banks
to hide precharge time and the capability to randomly
change column addresses on each clock cycle during burst
access.
A self-timed row precharge initiated at the end of the burst
sequence is available with the AUTO PRECHARGE func-
tion enabled. Precharge one bank while accessing one of the
other three banks will hide the precharge cycles and provide
seamless, high-speed, random-access operation.
SDRAM read and write accesses are burst oriented starting at
a selected location and continuing for a programmed num-
ber of locations in a programmed sequence. The registra-
tion of an ACTIVE command begins accesses, followed by
a READ or WRITE command. The ACTIVE command in
conjunction with address bits registered are used to select
the bank and row to be accessed (BA0, BA1 select the
bank; A0-A12 select the row). The READ or WRITE
commands in conjunction with address bits registered are
used to select the starting column location for the burst
access.
Programmable READ or WRITE burst lengths consist of 1,
2, 4 and 8 locations or full page, with a burst terminate
option.
FUNCTIONAL BLOCK DIAGRAM (FOR 4MX16X4 BANKS SHOWN)
CLK
CKE
CS
RAS
CAS
WE
DQML
DQMH
COMMAND
DECODER
&
CLOCK
GENERATOR
DATA IN
BUFFER
16
16
2
MODE
REGISTER
13
REFRESH
CONTROLLER
DQ 0-15
SELF
REFRESH
CONTROLLER
A10
A12
A11
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
BA0
BA1
DATA OUT
BUFFER
16
16
V
DD
/V
DDQ
V
ss
/V
ss
Q
REFRESH
COUNTER
8192
8192
8192
8192
ROW DECODER
MULTIPLEXER
MEMORY CELL
ARRAY
13
13
ROW
ADDRESS
LATCH
13
ROW
ADDRESS
BUFFER
BANK 0
SENSE AMP I/O GATE
COLUMN
ADDRESS LATCH
9
512
(x 16)
BANK CONTROL LOGIC
BURST COUNTER
COLUMN DECODER
COLUMN
ADDRESS BUFFER
9
2
Integrated Silicon Solution, Inc. — www.issi.com —
1-800-379-4774
PRELIMINARY INFORMATION Rev. 00E
05/25/06
ISSI [ INTEGRATED SILICON SOLUTION, INC ]
