GS881Z18AT GSI [GSI Technology], GS881Z18AT Datasheet - Page 11

• Manufacturer Part Number: GS881Z18AT
• Description: 9Mb Pipelined and Flow Through Synchronous NBT SRAM
• Manufacturer: GSI [GSI Technology]

Burst Cycles
Although NBT RAMs are designed to sustain 100% bus bandwidth by eliminating turnaround cycle when there is transition from
read to write, multiple back-to-back reads or writes may also be performed. NBT SRAMs provide an on-chip burst address
generator that can be utilized, if desired, to further simplify burst read or write implementations. The ADV control pin, when
driven high, commands the SRAM to advance the internal address counter and use the counter generated address to read or write
the SRAM. The starting address for the first cycle in a burst cycle series is loaded into the SRAM by driving the ADV pin low, into
Load mode.
Burst Order
The burst address counter wraps around to its initial state after four addresses (the loaded address and three more) have been
accessed. The burst sequence is determined by the state of the Linear Burst Order pin (LBO). When this pin is low, a linear burst
sequence is selected. When the RAM is installed with the LBO pin tied high, Interleaved burst sequence is selected. See the tables
below for details.
Mode Pin Functions
Note:
There is a pull-down device on the ZZ pin, so this input pin can be unconnected and the chip will operate in the default states as specified in
the above tables.
Burst Counter Sequences
Linear Burst Sequence
Note:
The burst counter wraps to initial state on the 5th clock.
Rev: 1.03 11/2004
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
2nd address
1st address
3rd address
4th address
FLXDrive Output Impedance Control
Output Register Control
Power Down Control
Burst Order Control
Mode Name
A[1:0] A[1:0] A[1:0] A[1:0]
00
01
10
11
01
10
11
00
10
00
01
11
11
00
01
10
Pin Name
11/31
LBO
ZQ
ZZ
FT
Interleaved Burst Sequence
Note:
The burst counter wraps to initial state on the 5th clock.
2nd address
1st address
3rd address
4th address
H or NC
H or NC
L or NC
State
H
H
L
L
L
GS881Z18/36AT-250/225/200/166/150/133
A[1:0] A[1:0] A[1:0] A[1:0]
00
01
10
11
High Drive (Low Impedance)
Low Drive (High Impedance)
01
00
11
10
Standby, I
Interleaved Burst
Flow Through
Linear Burst
Function
Pipeline
Active
10
00
01
11
DD
© 2001, GSI Technology
= I
SB
11
10
01
00
BPR 1999.05.18