GS8672Q20/38BE-500/450/400
165-Bump BGA
Commercial Temp
Industrial Temp
Features
• 2.5 Clock Latency
• On-Chip ECC with virtually zero SER
• Simultaneous Read and Write SigmaQuad™ Interface
• JEDEC-standard package
• Dual Double Data Rate interface
• Byte Write Capability
• Burst of 2 Read and Write
• On-Die Termination (ODT) on Data (D), Byte Write (BW),
and Clock (K, K) outputs
• 1.8 V +100/–100 mV core power supply
• 1.5 V HSTL Interface
• Pipelined read operation
• Fully coherent read and write pipelines
• ZQ pin for programmable output drive strength
• IEEE 1149.1 JTAG-compliant Boundary Scan
• Pin-compatible with 36Mb and144Mb devices
• 165-bump, 15 mm x 17 mm, 1 mm bump pitch BGA package
• RoHS-compliant 165-bump BGA package available
72Mb SigmaQuad-II+
TM
Burst of 2 ECCRAM
TM
Clocking and Addressing Schemes
500 MHz–400 MHz
1.8 V V
DD
1.5 V I/O
The GS8672Q20/38BE SigmaQuad-II+ ECCRAMs are
synchronous devices. They employ two input register clock
inputs, K and K. K and K are independent single-ended clock
inputs, not differential inputs to a single differential clock input
buffer.
Each internal read and write operation in a SigmaQuad-II+ B2
ECCRAM is two times wider than the device I/O bus. An input
data bus de-multiplexer is used to accumulate incoming data
before it is simultaneously written to the memory array. An
output data multiplexer is used to capture the data produced
from a single memory array read and then route it to the
appropriate output drivers as needed. Therefore the address
field of a SigmaQuad-II+ B2 ECCRAM is always one address
pin less than the advertised index depth (e.g., the 4M x18 has
an 2M addressable index).
On-Chip Error Correction Code
GSI's ECCRAMs implement an ECC algorithm that detects
and corrects all single-bit memory errors, including those
induced by Soft Error Rate (SER) events such as cosmic rays,
alpha particles. The resulting SER of these devices is
anticipated to be <0.002 FITs/Mb — a 5-order-of-magnitude
improvement over comparable SRAMs with no On-Chip ECC,
which typically have an SER of 200 FITs/Mb or more. SER
quoted above is based on reading taken at sea level.
However, the On-Chip Error Correction (ECC) will be
disabled if a “Half Write” operation is initiated. See the
Byte
Write Contol
section for further information.
SigmaQuad™ ECCRAM Overview
The GS8672Q20/38BE are built in compliance with the
SigmaQuad-II+ ECCRAM pinout standard for Separate I/O
synchronous ECCRAMs. They are 75,497,472-bit (72Mb)
ECCRAMs. The GS8672Q20/38BE SigmaQuad ECCRAMs
are just one element in a family of low power, low voltage
HSTL I/O ECCRAMs designed to operate at the speeds needed
to implement economical high performance networking
systems.
Parameter Synopsis
-500
tKHKH
tKHQV
2.0 ns
0.45 ns
-450
2.2 ns
0.45 ns
-400
2.5 ns
0.45 ns
Rev: 1.01a 6/2013
1/28
© 2011, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GS8672Q20/38BE-500/450/400
Pin Description Table
Symbol
SA
R
W
BW0–BW3
K
K
TMS
TDI
TCK
TDO
V
REF
ZQ
Qn
Dn
Description
Synchronous Address Inputs
Synchronous Read
Synchronous Write
Synchronous Byte Writes
Input Clock
Input Clock
Test Mode Select
Test Data Input
Test Clock Input
Test Data Output
HSTL Input Reference Voltage
Output Impedance Matching Input
Synchronous Data Outputs
Synchronous Data Inputs
Disable DLL when Low
Output Echo Clock
Output Echo Clock
Power Supply
Isolated Output Buffer Supply
Power Supply: Ground
Q Valid Output
On-Die Termination
No Connect
No Function
Type
Input
Input
Input
Input
Input
Input
Input
Input
Input
Output
Input
Input
Output
Input
Input
Output
Output
Supply
Supply
Supply
Output
Input
—
—
Comments
—
Active Low
Active Low
Active Low
Active High
Active Low
—
—
—
—
—
—
—
—
Active Low
—
—
1.8 V Nominal
1.5 or 1.8 V Nominal
—
—
—
—
—
Doff
CQ
CQ
V
DD
V
DDQ
V
SS
QVLD
ODT
NC
NF
Notes:
1. NC = Not Connected to die or any other pin.
2. NF= No Function. There is an electrical connection to this input pin, but the signal has no function in the device. It can be left unconnected,
or tied to V
SS
or V
DDQ.
3. K, or K cannot be set to V
REF
voltage.
Rev: 1.01a 6/2013
4/28
© 2011, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GS8672Q20/38BE-500/450/400
Background
Separate I/O SRAMs, from a system architecture point of view, are attractive in applications where alternating reads and writes are
needed. Therefore, the SigmaQuad-II+ ECCRAM interface and truth table are optimized for alternating reads and writes. Separate
I/O SRAMs are unpopular in applications where multiple reads or multiple writes are needed because burst read or write transfers
from Separate I/O ECCRAMs can cut the RAM’s bandwidth in half.
SigmaQuad-II+ B2 ECCRAM DDR Read
The read port samples the status of the Address Input and R pins at each rising edge of K. A Low on the Read Enable pin, R, begins
a read cycle. Data can be clocked out after the next rising edge of K with a rising edge of C (or by K if C and C are tied High), and
after the following rising edge of K with a rising edge of C (or by K if C and C are tied High). Clocking in a High on the Read
Enable pin, R, begins a read port deselect cycle.
SigmaQuad-II+ B2 ECCRAM DDR Write
The write port samples the status of the W pin at each rising edge of K and the Address Input pins on the following rising edge of
K. A Low on the Write Enable pin, W, begins a write cycle. The first of the data-in pairs associated with the write command is
clocked in with the same rising edge of K used to capture the write command. The second of the two data in transfers is captured on
the rising edge of K along with the write address. Clocking in a High on W causes a write port deselect cycle.
Rev: 1.01a 6/2013
5/28
© 2011, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
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