512K x 18, 256K x 36 ByteSafe鈩?/div>
100 MHz鈥?6 MHz
3.3 V V
DD
8Mb Sync Burst SRAMs
3.3 V and 2.5 V I/O
counter may be configured to count in either linear or
interleave order with the Linear Burst Order (LBO) input. The
Burst function need not be used. New addresses can be loaded
on every cycle with no degradation of chip performance.
Flow Through/Pipeline Reads
The function of the Data Output register can be controlled by
the user via the FT mode pin (Pin 14). Holding the FT mode
pin low places the RAM in Flow Through mode, causing
output data to bypass the Data Output Register. Holding FT
high places the RAM in Pipeline mode, activating the rising-
edge-triggered Data Output Register.
DCD Pipelined Reads
The GS881E18//36T is a DCD (Dual Cycle Deselect)
pipelined synchronous SRAM. SCD (Single Cycle Deselect)
versions are also available. DCD SRAMs pipeline disable
commands to the same degree as read commands. DCD RAMs
hold the deselect command for one full cycle and then begin
turning off their outputs just after the second rising edge of
clock.
Byte Write and Global Write
Byte write operation is performed by using Byte Write enable
(BW) input combined with one or more individual byte write
signals (Bx). In addition, Global Write (GW) is available for
writing all bytes at one time, regardless of the byte write
control inputs.
ByteSafe鈩?Parity Functions
Functional Description
Applications
The GS881E18//36T is a 9,437,184-bit high performance
synchronous SRAM with a 2-bit burst address counter.
Although of a type originally developed for Level 2 Cache
applications supporting high performance CPUs, the device
now finds application in synchronous SRAM applications,
ranging from DSP main store to networking chip set support.
The GS881E18/36T features ByteSafe data security functions.
See detailed discussion following.
Sleep Mode
Low power (Sleep mode) is attained through the assertion
(high) of the ZZ signal, or by stopping the clock (CK).
Memory data is retained during Sleep mode.
Core and Interface Voltages
The GS881E18//36T operates on a 3.3 V power supply, and all
inputs/outputs are 3.3 V- and 2.5 V-compatible. Separate
output power (V
DDQ
) pins are used to decouple output noise
from the internal circuit.
Controls
Addresses, data I/Os, chip enables (E1, E2), address burst
control inputs (ADSP, ADSC, ADV) and write control inputs
(Bx, BW, GW) are synchronous and are controlled by a
positive-edge-triggered clock input (CK). Output enable (G)
and power down control (ZZ) are asynchronous inputs. Burst
cycles can be initiated with either ADSP or ADSC inputs. In
Burst mode, subsequent burst addresses are generated
internally and are controlled by ADV. The burst address
Rev: 1.10 9/2000
1/34
漏 2000, Giga Semiconductor, Inc.
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.