GS81284Z18/36B-250/200/167
Burst Counter Sequences
Linear Burst Sequence
Interleaved Burst Sequence
A[1:0] A[1:0] A[1:0] A[1:0]
A[1:0] A[1:0] A[1:0] A[1:0]
1st address
2nd address
3rd address
4th address
00
01
10
11
01
10
11
00
10
11
00
01
11
00
01
10
1st address
2nd address
3rd address
4th address
00
01
10
11
01
00
11
10
10
11
00
01
11
10
01
00
Note:
Note:
The burst counter wraps to initial state on the 5th clock.
The burst counter wraps to initial state on the 5th clock.
BPR 1999.05.18
Sleep Mode
During normal operation, ZZ must be pulled low, either by the user or by its internal pull down resistor. When ZZ is pulled high,
the SRAM will enter a Power Sleep mode after 2 cycles. At this time, internal state of the SRAM is preserved. When ZZ returns to
low, the SRAM operates normally after 2 cycles of wake up time.
Sleep mode is a low current, power-down mode in which the device is deselected and current is reduced to I 2. The duration of
SB
Sleep mode is dictated by the length of time the ZZ is in a High state. After entering Sleep mode, all inputs except ZZ become
disabled and all outputs go to High-Z The ZZ pin is an asynchronous, active high input that causes the device to enter Sleep mode.
When the ZZ pin is driven high, I 2 is guaranteed after the time tZZI is met. Because ZZ is an asynchronous input, pending
SB
operations or operations in progress may not be properly completed if ZZ is asserted. Therefore, Sleep mode must not be initiated
until valid pending operations are completed. Similarly, when exiting Sleep mode during tZZR, only a Deselect or Read commands
may be applied while the SRAM is recovering from Sleep mode.
Sleep Mode Timing Diagram
tKH
tKC
tKL
CK
ZZ
tZZR
tZZS
tZZH
Designing for Compatibility
The GSI NBT SRAMs offer users a configurable selection between Flow Through mode and Pipeline mode via the FT signal. Not
all vendors offer this option, however most mark the pin V or V on pipelined parts and V on flow through parts. GSI NBT
DD
DDQ
SS
SRAMs are fully compatible with these sockets. Other vendors mark the pin as a No Connect (NC). GSI RAMs have an internal
pull-up device on the FT pin so a floating FT pin will result in pipelined operation. If the part being replaced is a pipelined mode
part, the GSI RAM is fully compatible with these sockets. In the unlikely event the part being replaced is a Flow Through device,
the pin will need to be pulled low for correct operation.
Rev: 1.02 7/2010
11/29
© 2007, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GSI [ GSI TECHNOLOGY ]
