• Default to SCD x18/x36 Interleaved Pipeline mode
• Byte Write (BW
• Internal self-timed write cycle
• Automatic power-down for portable applications
• JEDEC-standard 119-bump and 165-bump BGA packages
• Pb-Free 119-bump and 165-bump BGA packages available
) and/or Global Write (GW) operation
/low output drive
Functional Description
Applications
The GS88237BB/D is a 9,437,184-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
inputs (ADSP
BW
, GW) are synchronous and are controlled by a positiveedge-triggered clock input (CK). Output enable (G
down control (ZZ) are asynchronous inputs. Burst cycles can
be initiated with either ADSP
subsequent burst addresses are generated internally and are
controlled by ADV
configured to count in either linear or interleave order with the
Linear Burst Order (LBO
be used. New addresses can be loaded on every cycle with no
degradation of chip performance.
, ADSC, ADV), and write control inputs (Bx,
or ADSC inputs. In Burst mode,
. The burst address counter may be
) input. The Burst function need not
), address burst control
) and power
333 MHz–200 MHz
2.5 V or 3.3 V V
DD
2.5 V or 3.3 V I/O
SCD and DCD Pipelined Reads
The GS88237BB/D is a SCD (Single Cycle Deselect) and
DCD (Dual Cycle Deselect) pipelined synchronous SRAM.
DCD SRAMs pipeline disable commands to the same degree
as read commands. SCD SRAMs pipeline deselect commands
one stage less than read commands. SCD RAMs begin turning
off their outputs immediately after the deselect command has
been captured in the input registers. 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. The user
may configure this SRAM for either mode of operation using
the SCD mode input.
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
writing all bytes at one time, regardless of the Byte Write
control inputs.
FLXDrive™
The ZQ pin allows selection between high drive strength (ZQ
low) for multi-drop bus applications and normal drive strength
(ZQ floating or high) point-to-point applications. See the
Output Driver Characteristics chart for details.
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 GS88237BB/D operates on a 2.5 V or 3.3 V power supply.
All input are 3.3 V and 2.5 V compatible. Separate output
power (V
internal circuits and are 3.3 V and 2.5 V compatible.
). In addition, Global Write (GW) is available for
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GS88237BB/D-333/300/250/200
Mode Pin Functions
Mode NamePin NameStateFunction
Burst Order ControlLBO
Power Down ControlZZ
Single/Dual Cycle Deselect ControlSCD
FLXDrive Output Impedance ControlZQ
9th Bit EnablePE
Note:
There are pull-up devices onthe ZQ, SCD 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.
Burst Counter Sequences
LLinear Burst
HInterleaved Burst
L or NCActive
H
LDual Cycle Deselect
H or NCSingle Cycle Deselect
LHigh Drive (Low Impedance)
H or NCLow Drive (High Impedance)
LActivate DQPx I/Os (x18/x36 mode)
H or NCDeactivate DQPx I/Os (x16/x32 mode)
Standby, I
DD
= I
SB
Linear Burst Sequence
A[1:0] A[1:0] A[1:0] A[1:0]
1st address00011011
2nd address01101100
3rd address10110001
4th address11000110
Note:
The burst counter wraps to initial state on the 5th clock.
Interleaved Burst Sequence
A[1:0] A[1:0] A[1:0] A[1:0]
1st address00011011
2nd address01001110
3rd address10110001
4th address11100100
Note:
The burst counter wraps to initial state on the 5th clock.