GS8180D18D-250/200/167/133/100
165-Bump BGA
Commercial Temp
Industrial Temp
Features
• Simultaneous Read and Write SigmaQuad™ Interface
• JEDEC-standard pinout and package
• Dual Double Data Rate interface
• Byte Write controls sampled at data-in time
• Burst of 4 Read and Write
• 1.8 V +150/–100 mV core power supply
• 1.5 V or 1.8 V HSTL Interface
• Pipelined read operation
• Fully coherent read and write pipelines
• ZQ mode pin for programmable output drive strength
• IEEE 1149.1 JTAG-compliant Boundary Scan
• 165-bump, 13 mm x 15 mm, 1 mm bump pitch BGA package
• Pin-compatible with future 36Mb, 72Mb, and 144Mb devices
• Pb-Free 165-bump BGA package available
18Mb Burst of 4
SigmaQuad SRAM
250 MHz–100 MHz
1.8 V V
DD
1.8 V or 1.5 V I/O
SigmaRAM™ Family Overview
GS8180D18 are built in compliance with the SigmaQuad
SRAM pinout standard for Separate I/O synchronous SRAMs.
They are 18,874,368-bit (18Mb) SRAMs. These are the first in
a family of wide, very low voltage HSTL I/O SRAMs designed
to operate at the speeds needed to implement economical high
performance networking systems.
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Parameter Synopsis
-200
5.0 ns
2.3 ns
-167
6.0 ns
2.5 ns
-133
7.5 ns
3.0 ns
-100
10 ns
3.0 ns
tKHKH
4.0 ns
tKHQV
2.1 ns
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SigmaQuad SRAMs are offered in a number of configurations.
Some emulate and enhance other synchronous separate I/O
SRAMs. A higher performance SDR (Single Data Rate) Burst
of 2 version is also offered. The logical differences between
the protocols employed by these RAMs hinge mainly on
various combinations of address bursting, output data
registering, and write cueing. Along with the Common I/O
family of SigmaRAMs, the SigmaQuad family of SRAMs
allows a user to implement the interface protocol best suited to
the task at hand.
Clocking and Addressing Schemes
A Burst of 4 SigmaQuad SRAM is a synchronous device. It
employs 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. The device also
allows the user to manipulate the output register clock inputs
quasi independently with the C and C clock inputs. C and C are
also independent single-ended clock inputs, not differential
inputs. If the C clocks are tied high, the K clocks are routed
internally to fire the output registers instead.
Because Separate I/O Burst of 4 RAMs always transfer data in
four packets, A0 and A1 are internally set to 0 for the first read
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
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© 2002, GSI Technology
GS8180D18D-250/200/167/133/100
1M x 18 SigmaQuad SRAM—Top View (Package D)
1
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
TDO
2
MCL/SA
(144Mb)
Q9
NC
D11
NC
Q12
D13
V
REF
NC
NC
Q15
NC
D17
NC
TCK
3
NC/SA
(36Mb)
D9
D10
Q10
Q11
D12
Q13
V
DDQ
D14
Q14
D15
D16
Q16
Q17
SA
4
W
SA
V
SS
V
SS
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
SS
V
SS
SA
5
BW1
NC
SA
V
SS
V
SS
V
DD
V
DD
V
DD
V
DD
V
DD
V
SS
V
SS
SA
6
K
K
7
NC
BW0
SA
8
R
SA
9
SA
10
MCL/SA
(72Mb)
NC
Q7
NC
D6
NC
NC
V
REF
Q4
D3
NC
Q1
NC
D0
TMS
11
NC
Q8
D8
D7
Q6
Q5
D5
ZQ
D4
Q3
Q2
D2
D1
Q0
TDI
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SA
SA
SA
11 x 15 Bump BGA—13 x 15 mm2 Body—1 mm Bump Pitch
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Notes:
1. Expansion addresses: A3 for 36Mb, A10 for 72Mb, A2 for 144Mb
2. BW0 controls writes to D0:D8. BW1 controls writes to D9:D17.
3. MCL = Must Connect Low
4. It is recommended that H1 be tied low for compatibility with future devices.
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NC
V
SS
NC
NC
NC
NC
NC
V
SS
V
SS
V
SS
V
SS
V
SS
V
SS
V
SS
V
SS
V
SS
SA
C
C
V
SS
V
SS
V
SS
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
DDQ
V
SS
V
SS
SA
SA
V
DD
V
DD
V
DD
V
DD
V
DD
V
SS
V
SS
SA
SA
SA
NC
NC
NC
NC
NC
NC
SA
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
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NC
V
DDQ
© 2002, GSI Technology
GS8180D18D-250/200/167/133/100
Pin Description Table
Symbol
SA
NC
R
W
BW0–BW1
K
K
C
C
TMS
TDI
TCK
TDO
V
REF
ZQ
MCL
D0–D17
Q0–Q17
V
DD
V
DDQ
V
SS
Description
Synchronous Address Inputs
No Connect
Synchronous Read
Synchronous Write
Synchronous Byte Writes
Input Clock
Input Clock
Output Clock
Output Clock
Test Mode Select
Test Data Input
Test Clock Input
Test Data Output
HSTL Input Reference Voltage
Output Impedance Matching Input
Must Connect Low
Synchronous Data Inputs
Power Supply
Type
Input
—
Input
Comments
—
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Input
Input
Input
Input
Input
Input
Input
Input
Input
Output
Input
Input
—
Input
Output
Supply
Supply
Supply
ct
Active Low
Active Low
Active Low
Active High
Active Low
Active High
Active Low
—
—
—
—
—
—
—
—
—
1.8 V Nominal
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Isolated Output Buffer Supply
Power Supply: Ground
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Synchronous Data Outputs
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1.8 or 1.5 V Nominal
—
Note:
NC = Not Connected to die or any other pin
Background
A SigmaQuad SRAM can begin an alternating sequence of reads and writes with either a read or a write. In order for any separate
I/O SRAM that shares a common address between its two ports to keep both ports running all the time, the RAM must implement
some sort of burst transfer protocol. The burst must be at least long enough to cover the time the opposite port is receiving
instructions on what to do next. The rate at which a RAM can accept a new random address is the most fundamental performance
metric for the RAM. Each of the three SigmaQuad SRAMs support similar address rates because random address rate is
determined by the internal performance of the RAM and they are all based on the same internal circuits. Differences between the
truth tables of the different SigmaQuad SRAMs, or any other Separate I/O SRAMs, follow from differences in how the RAM’s
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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 SRAM 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 SRAMs can cut the RAM’s bandwidth in half.
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© 2002, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GS8180D18D-250/200/167/133/100
interface is contrived to interact with the rest of the system. Each mode of operation has its own advantages and disadvantages. The
user should consider the nature of the work to be done by the RAM to evaluate which version is best suited to the application at
hand.
Alternating Read-Write Operations
SigmaQuad SRAMs follow a few simple rules of operation.
- Read or Write commands issued on one port are never allowed to interrupt an operation in progress on the other port.
- Read or Write data transfers in progress may not be interrupted and re-started.
- R and W high always deselects the RAM.
- All address, data, and control inputs are sampled on clock edges.
In order to enforce these rules, each RAM combines present state information with command inputs. See the Truth Table for
details.
Burst of 4 SigmaQuad SRAM DDR Read
The status of the Address Input, W, and R pins are sampled at each rising edge of K. W and R high causes chip disable. A low on
the Read Enable-bar pin, R, begins a read cycle. R is always ignored if the previous command loaded was a read command. The
four resulting data output transfers begin after the next rising edge of the K clock. Data is clocked out by the next rising edge of the
C, the rising edge of C after that, the next rising edge of C, and finally by the next rising edge of C.
Burst of 4 Double Data Rate SigmaQuad SRAM Read First
Read A
K
K
Address
R
W
BWx
D
C
C
Q
A
B
NOP
Read B
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Write C
Read D
C
D
E
C
C+1
C+2
ct
Write E
NOP
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C+3
E
E+1
A
A+1
A+2
A+3
B
B+1
B+2
B+3
D
D+1
D+2
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© 2002, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
GS8180D18D-250/200/167/133/100
Burst of 4 SigmaQuad SRAM DDR Write
The status of the Address Input, W, and R pins are sampled at each rising edge of K. W and R high causes chip disable. A low on
the Write Enable-bar pin, W, and a high on the Read Enable-bar pin, R, begins a write cycle. W is always ignored if the previous
command was a write command. Data is clocked in by the next rising edge of K, the rising edge of K after that, the next rising edge
of K, and finally by the next rising edge of K.
K
Kbar
Address
Rbar
Wbar
BWx bar
D
C
Cbar
Q
A
A+1
A+2
A+3
A
B
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C
D
B+3
B+3
B
B+1
B+2
C
Write A
NOP
Write B
Read C
NOP
ct
C+1
Burst of 4 Double Data Rate SigmaQuad SRAM Write First
Read D
NOP
C+2
C+3
D
Special Functions
Each write enable command and write address loaded into the RAM provides the base address for a 4 beat data transfer. The x18
version of the RAM, for example, may write 72 bits in association with each address loaded. Any 9-bit byte may be masked in any
write sequence.
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Byte Write Control
Byte Write Enable pins are sampled at the same time that Data In is sampled. A high on the Byte Write Enable pin associated with
a particular byte (e.g., BW0 controls D0–D8 inputs) will inhibit the storage of that particular byte, leaving whatever data may be
stored at the current address at that byte location undisturbed. Any or all of the Byte Write Enable pins may be driven high or low
during the data in sample times in a write sequence.
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© 2002, GSI Technology
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
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