Rev: 1.01 11/2000
Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.
1/33
2000, Giga Semiconductor, Inc.
A
Advanced Information
GS8180D09/18B-333/300/275/250
2M x 9, 1M x 18
Separate I/O Sigma DDR SRAM
333 MHz
1.8 V V
DD
1.8 V and 1.5 V I/
209-Bump BGA
Commercial Temp
Industrial Temp
Σ
RAM
Features
Double Data Rate Read and Write mode
Observes the Sigma RAM pinout standard
1.8 V +150/–100 mV core power supply
1.5 V or 1.8 V I/O supply
Pipelined read operation
Fully coherent read and write pipelines
Echo Clock outputs track data output drivers
ZQ mode pin for user-selectable output drive strength
2 user-programmable chip enable inputs for easy depth
expansion
IEEE 1149.1 JTAG-compatible Boundary Scan
209-bump, 14 mm x 22 mm, 1 mm bump pitch BGA package
Pin compatible with future 32M, 64M and 128M devices
Sigma RAM Family Overview
The GS8180D09/18B are built in compliance with the Sigma
RAM pinout standard for Separate I/O synchronous SRAMs.
They are 18,874,368-bit (16Mb) SRAMs. These are the first in
a family of wide, very low voltage CMOS I/O SRAMs
designed to operate at the speeds needed to implement
economical high performance networking systems.
GSI's family of Common I/O
Σ
RAMs are offered in a number
of configurations that emulate other synchronous SRAMs,
such as Burst RAMs, NBT RAMs, Late Write, or Double Data
Rate (DDR) SRAMs. The logical differences between the
protocols employed by these RAMs hinge mainly on various
combinations of address bursting, output data registering, and
write cueing.
Σ
RAMs allow a user to implement the interface
protocol best suited to the task at hand.
Functional Description
Because a Sigma RAM is a synchronous device, address, and
read/ write control inputs are captured on the rising edge of the
input clock. 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. In
DDR mode the device captures Data In on both rising and
falling edges of clock and drives data on both clock edges as
well.
Because the Separate I/O DDR
Σ
RAM always transfers data in
four packets, A0 and A1 are internally set to 0 for the first read
or write transfer, and automatically incremented by 1 for the
next transfer. Since the LSBs are tied off internally, the address
field of a Separate I/O DDR
Σ
RAM is always two address pins
less than the advertised index depth (e.g., the 1M x 18 has a
256K addressable index).
Single Data Rate (SDR) Separate I/O Sigma RAMs implement
a pipelined read and incorporate a rising-edge-triggered output
register. In DDR mode, rising- and falling-edge-triggered
output registers are employed. For read cycles, a DDR
SRAM’s 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 and subsequent
falling edge of clock.
GS818x18/36B
Σ
RAMs are implemented with GSI's high
performance CMOS technology and are packaged in a 209-
bump BGA.
- 333
3.0 ns
1.5 ns
Pipeline Mode
tKHKH
tKHQV
209-Bump, 14 mm x 22 mm BGA
1 mm Bump Pitch, 11 x 19 Bump Array
Bottom View