
Preliminary
GS8640Z18/36T-xxxV
72Mb Pipelined and Flow Through
Synchronous NBT SRAM
250 MHz
–
167 MHz 
1.8 V or 2.5 V V
DD
1.8 V or 2.5 V I/O
100-Pin TQFP
Commercial Temp
Industrial Temp
Rev:  1.01  6/2006
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
1/22
 2004, GSI Technology
Features
 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 
ZBT SRAMs
 1.8 V or 2.5 V core power supply
 1.8 V or 2.5 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
Functional Description
The GS8640Z18/36T-xxxV 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-xxxV  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 
clock. 
The  GS8640Z18/36T-xxxV is implemented with GSI's high 
performance CMOS technology and is available in a JEDEC-
standard 100-pin TQFP package.
Parameter Synopsis
-250
3.0
4.0
340
410
6.5
6.5
245
280
-200
3.0
5.0
290
350
7.5
7.5
220
250
-167
3.5
6.0
260
305
8.0
8.0
210
240
Unit
ns
ns
mA
mA
ns
ns
mA
mA
Pipeline
3-1-1-1
t
KQ
tCycle
Curr 
(x18)
Curr 
(x32/x36)
t
KQ
tCycle
Curr 
(x18)
Curr 
(x32/x36)
Flow Through
2-1-1-1