time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are
advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products.
Integrated Silicon Solution, Inc. — www.issi.com
Rev. D
07/28/08
1
IS42S83200B,
IS42S16160B
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
Microchip MCU
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