
Preliminary
GS8640E18/32/36T-xxxV
4M x 18, 2M x 32, 2M x 36
72Mb Sync Burst SRAMs
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.
1/23
 2004, GSI Technology
Features
 FT pin for user-configurable flow through or pipeline 
operation
  Dual Cycle Deselect (DCD) operation
 1.8 V or 2.5 V core power supply
 1.8 V or 2.5 V I/O supply
 LBO pin for Linear or Interleaved Burst mode
 Internal input resistors on mode pins allow floating mode pins
 Default to 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 100-lead TQFP package
 RoHS-compliant 100-lead TQFP package available
Functional Description
Applications
The GS8640E18/32/36T-xxxV is a 75,497,472-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. 
Controls 
Addresses, data I/Os, chip enables (E1, E2, E3), 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.
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 GS8640E18/32/36T-xxxV 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. 
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 GS8640E18/32/36T-xxxV operates on a 1.8 V or 2.5 V 
power supply. All inputs are 1.8 V or 2.5 V compatible. 
Separate output power (V
DDQ
) pins are used to decouple 
output noise from the internal circuits and are 1.8 V or 2.5 V 
compatible.
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