The 128Mb SDRAM is a high speed CMOS, dynamic
random-access memory designed to operate in 3.3V Vdd
and 3.3V Vddq memory systems containing 134,217,728
bits. Internally configured as a quad-bank DRAM with a
synchronous interface. Each 33,554,432-bit bank is orga-
nized as 4,096 rows by 512 columns by 16 bits or 4,096
rows by 1,024 columns by 8 bits.
The 128Mb 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 128Mb 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
A self-timed row precharge initiated at the end of the burst
sequence is available with the AUTO PRECHARGE function
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
number of locations in a programmed sequence. The
registration 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-A11 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
FUNCTIONAL BLOCK DIAGRAM (For 2MX16X4 Banks OnlY)
SENSE AMP I/O GATE
BANK CONTROL LOGIC
2 Integrated Silicon Solution, Inc. — www.issi.com