72Mb Pipelined and Flow Through
Synchronous NBT SRAM
300 MHz–167 MHz
2.5 V or 3.3 V VDD
2.5 V or 3.3 V I/O
• NBT (No Bus Turn Around) functionality allows zero wait
read-write-read bus utilization; Fully pin-compatible with
both pipelined and flow through NtRAM™, NoBL™ and
• 2.5 V or 3.3 V +10%/–10% core power supply
• 2.5 V or 3.3 V I/O supply
• User-configurable Pipeline and Flow Through mode
• LBO pin for Linear or Interleave Burst mode
• Pin compatible with 4Mb, 9Mb, 18Mb and 36Mb devices
• Byte write operation (9-bit Bytes)
• 3 chip enable signals for easy depth expansion
• ZZ Pin for automatic power-down
• JEDEC-standard 100-lead TQFP package
• RoHS-compliant 100-lead TQFP package available
The GS8640Z18/36T is a 72Mbit Synchronous Static SRAM.
GSI's NBT SRAMs, like ZBT, NtRAM, NoBL or other
pipelined read/double late write or flow through read/single
late write SRAMs, allow utilization of all available bus
bandwidth by eliminating the need to insert deselect cycles
when the device is switched from read to write cycles.
Because it is a synchronous device, address, data inputs, and
read/ write control inputs are captured on the rising edge of the
input clock. Burst order control (LBO) must be tied to a power
rail for proper operation. Asynchronous inputs include the
Sleep mode enable (ZZ) and Output Enable. Output Enable can
be used to override the synchronous control of the output
drivers and turn the RAM's output drivers off at any time.
Write cycles are internally self-timed and initiated by the rising
edge of the clock input. This feature eliminates complex off-
chip write pulse generation required by asynchronous SRAMs
and simplifies input signal timing.
The GS8640Z18/36T may be configured by the user to operate
in Pipeline or Flow Through mode. Operating as a pipelined
synchronous device, meaning that in addition to the rising edge
triggered registers that capture input signals, the device
incorporates a rising-edge-triggered output register. For read
cycles, pipelined SRAM output data is temporarily stored by
the edge triggered output register during the access cycle and
then released to the output drivers at the next rising edge of
The GS8640Z18/36T is implemented with GSI's high
performance CMOS technology and is available in a JEDEC-
standard 100-pin TQFP package.
-300 -250 -200 -167 Unit
2.3 2.5 3.0 3.5 ns
3.3 4.0 5.0 6.0 ns
400 340 290 260 mA
480 410 350 305 mA
5.5 6.5 7.5 8.0 ns
5.5 6.5 7.5 8.0 ns
285 245 220 210 mA
330 280 250 240 mA
*All GSI Technology packages are at least 5/6 RoHS compliant.
Packages listed with the additional “G” designator are 6/6 RoHS compliant.
Rev: 1.01 1/2006
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
© 2004, GSI Technology