Product Preview
GS8645Z18/36T-250/225/200/166/150/133
100-Pin TQFP
Commercial Temp
Industrial Temp
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
• 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 2Mb, 4Mb, 8Mb, and 16Mb 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
-250 -225 -200 -166 -150 -133 Unit
2.5 2.7 3.0 3.5 3.8 4.0 ns
4.0 4.4 5.0 6.0 6.7 7.5 ns
385
450
6.5
6.5
290
320
360 335 305 295 265 mA
415 385 345 325 295 mA
7.0 7.5 8.0 8.5 8.5 ns
7.0 7.5 8.0 8.5 8.5 ns
280 265 255 240 225 mA
310 290 280 265 245 mA
72Mb Pipelined and Flow Through
Synchronous NBT SRAM
250 MHz–133 MHz
2.5 V or 3.3 V V
DD
2.5 V or 3.3 V I/O
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 GS8645Z18/36T 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
clock.
The GS8645Z18/36T is implemented with GSI's high
performance CMOS technology and is available in a JEDEC-
standard 100-pin TQFP package.
t
KQ
tCycle
Pipeline
3-1-1-1
Curr
(x18)
Curr
(x32/x36)
t
KQ
Flow
tCycle
Through
Curr
(x18)
2-1-1-1
Curr
(x32/x36)
Functional Description
The GS8645Z18/36T 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
Flow Through and Pipelined NBT SRAM Back-to-Back Read/Write Cycles
Clock
Address
Read/Write
A
R
B
W
Q
A
C
R
D
B
Q
A
1/23
D
W
Q
C
D
B
E
R
D
D
Q
C
F
W
Q
E
D
D
Q
E
Flow Through
Data I/O
Pipelined
Data I/O
Rev: 1.00 4/2003
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
© 2003, Giga Semiconductor, Inc.
NoBL is a trademark of Cypress Semiconductor Corp.. NtRAM is a trademark of Samsung Electronics Co.. ZBT is a trademark of Integrated Device Technology, Inc.
Product Preview
GS8645Z18/36T-250/225/200/166/150/133
100-Pin TQFP Pin Descriptions
Symbol
A
0
, A
1
A
CK
B
A
B
B
B
C
B
D
W
E
1
E
2
E
3
G
ADV
CKE
DQ
A
DQ
B
DQ
C
DQ
D
ZZ
FT
LBO
V
DD
V
SS
V
DDQ
NC
Type
In
In
In
In
In
In
In
In
In
In
In
In
In
In
I/O
I/O
I/O
I/O
In
In
In
In
In
In
—
Description
Burst Address Inputs; Preload the burst counter
Address Inputs
Clock Input Signal
Byte Write signal for data inputs DQ
A1
-DQ
A9
; active low
Byte Write signal for data inputs DQ
B1
-DQ
B9
; active low
Byte Write signal for data inputs DQ
C1
-DQ
C9
; active low
Byte Write signal for data inputs DQ
D1
-DQ
D9
; active low
Write Enable; active low
Chip Enable; active low
Chip Enable; Active High. For self decoded depth expansion
Chip Enable; Active Low. For self decoded depth expansion
Output Enable; active low
Advance/Load; Burst address counter control pin
Clock Input Buffer Enable; active low
Byte A Data Input and Output pins
Byte B Data Input and Output pins
Byte C Data Input and Output pins
Byte D Data Input and Output pins
Power down control; active high
Pipeline/Flow Through Mode Control; active low
Linear Burst Order; active low
Core power supply
Ground
Output driver power supply
No Connect
Rev: 1.00 4/2003
4/23
© 2003, Giga Semiconductor, Inc.
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
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