GS8644Z18 ETC [List of Unclassifed Manufacturers], GS8644Z18 Datasheet - Page 16

• Manufacturer Part Number: GS8644Z18
• Description: 72Mb Pipelined and Flow Through Synchronous NBT SRAM
• Manufacturer: ETC [List of Unclassifed Manufacturers]

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.
FLXDrive™
The ZQ pin allows selection between NBT RAM nominal drive strength (ZQ low) for multi-drop bus applications and low drive
strength (ZQ floating or high) point-to-point applications. See the Output Driver Characteristics chart for details.
Mode Pin Functions
Note:
There are pull-up devices onthe ZQ and FT pins and a pull-down device on the ZZ pin, so those input pins can be unconnected and the chip
will operate in the default states as specified in the above tables.
Rev: 1.03 11/2004
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
FLXDrive Output Impedance Control
Output Register Control
Power Down Control
Burst Order Control
Mode Name
Pin Name
16/39
LBO
ZQ
ZZ
FT
GS8644Z18(B/E)/GS8644Z36(B/E)/GS8644Z72(C)
H or NC
H or NC
L or NC
State
H
H
L
L
L
High Drive (Low Impedance)
Low Drive (High Impedance)
Standby, I
Interleaved Burst
Flow Through
Linear Burst
Function
Pipeline
Active
DD
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© 2003, GSI Technology
= I
SB