
Rev:  1.01  11/2000
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
ByteSafe is a Trademark of Giga Semiconductor, Inc. (GSI Technology).
1/31
 1999, Giga Semiconductor, Inc.
Preliminary
GS8151E18/36T-225/200/180/166/150/133
1M x 18, 512K x 36
16Mb  Sync Burst SRAMs
225 MHz
–
133 MHz
3.3 V V
DD
2.5 V or 3.3 V I/O
100-Pin TQFP
Commercial Temp
Industrial Temp
Features
 FT pin for user-configurable flow through or pipeline opera-
tion
 Dual Cycle Deselect (DCD) operation
 IEEE 1149.1 JTAG-compatible Boundary Scan
 On-chip read parity checking; even or odd selectable
 3.3 V +10%/
–
5% core power supply
 2.5 V or 3.3 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
Functional Description
Applications
The GS8151E18/36T is a 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. 
Controls 
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.
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 GS8151E18/36T 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 Parity Functions
The GS8151E18/36  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 GS8151E18/36T operates on a 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.
-225 -200 -180 -166 -150 -133 Unit
4.4
2.5
205
240
210
210
210
7.0
8.5
350
410
370
340
315
Flow
Through
2-1-1-1
tCycle
t
KQ
Curr (x18)
Curr (x36)
t
KQ
tCycle
Curr (x18)
Curr (x36)
5.0
3.0
185
5.5
3.2
185
6.0
3.5
185
6.6
3.8
185
210
10.0
10.0
250
290
7.5
4.0
140
160
11.0
15.0
230
260
ns
ns
mA
mA
ns
ns
mA
mA
Pipeline
3-1-1-1
7.5
10.0
315
8.0
10.0
290
8.5
10.0
270