Preliminary
GS816218/36BB
119--Bump BGA
Commercial Temp
Industrial Temp
Features
• FT pin for user-configurable flow through or pipeline operation
• Single/Dual Cycle Deselect selectable
• IEEE 1149.1 JTAG-compatible Boundary Scan
• ZQ mode pin for user-selectable high/low output drive
• 2.5 V or 3.3 V +10%/–10% core power supply
• LBO pin for Linear or Interleaved Burst mode
• Internal input resistors on mode pins allow floating mode pins
• Default to SCD x18/x36 Interleaved Pipeline mode
• Byte Write (BW) and/or Global Write (GW) operation
• Internal self-timed write cycle
• Automatic power-down for portable applications
• JEDEC-standard 119-bump BGA package
1M x 18, 512K x 36
18Mb S/DCD Sync Burst SRAMs
Flow Through/Pipeline Reads
250 MHz–150 MHz
2.5 V or 3.3 V V
DD
2.5 V or 3.3 V I/O
The function of the Data Output register can be controlled by the user
via the FT mode . 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.
SCD and DCD Pipelined Reads
The GS816218/36BB is an SCD (Single Cycle Deselect) and DCD
(Dual Cycle Deselect) pipelined synchronous SRAM. DCD SRAMs
pipeline disable commands to the same degree as read commands.
SCD SRAMs pipeline deselect commands one stage less than read
commands. SCD RAMs begin turning off their outputs immediately
after the deselect command has been captured in the input registers.
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. The user may configure this SRAM for either mode of
operation using the SCD mode input.
Functional Description
Applications
The GS816218/36BB is an 18,874,368-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.
Addresses, data I/Os, chip enable (E1), 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
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.
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.
Controls
FLXDrive™
The ZQ pin allows selection between high drive strength (ZQ low) for
multi-drop bus applications and normal drive strength (ZQ floating or
high) point-to-point applications. See the Output Driver
Characteristics chart for details.
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 GS816218/36BB operates on a 2.5 V or 3.3 V power supply. All
input are 3.3 V and 2.5 V compatible. Separate output power (V
DDQ
)
pins are used to decouple output noise from the internal circuits and
are 3.3 V and 2.5 V compatible.
Parameter Synopsis
-250
Pipeline
3-1-1-1
t
KQ
tCycle
Curr (x18)
Curr (x36)
t
KQ
tCycle
Curr (x18)
Curr (x36)
2.5
4.0
280
330
5.5
5.5
210
240
-200
3.0
5.0
230
270
6.5
6.5
185
205
-150
3.8
6.7
185
210
7.5
7.5
170
190
Unit
ns
ns
mA
mA
ns
ns
mA
mA
Flow Through
2-1-1-1
Rev: 1.0 9/2004
1/31
© 2004, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GSI [ GSI TECHNOLOGY ]
