GSI GS8180D18D-333I, GS8180D18D-333, GS8180D18D-300I, GS8180D18D-300, GS8180D18D-250I Datasheet

Rev: 2.00f 6/2002 1/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

18Mb Σ2x2B4

SigmaQuad SRAM

200 MHz–333 MHz

1.8 V V

DD

1.8 V and 1.5 V I/O

165-Bump BGA
Commercial Temp
Industrial Temp

Features

• Simultaneous Read and Write SigmaQuad™ Interface

• JEDEC-standard pinout and package

• Dual Double Data Rate interface

• Echo Clock outputs track data output drivers

• 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

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.

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

Σ

2x2B4 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. Each

Σ

2x2B4

SigmaQuad SRAM also supplies Echo Clock outputs, CQ and CQ

,
that are synchronized with read data output. When used in a source
synchronous clocking scheme, these Echo Clock outputs can be used
to fire input registers at the data’s destination.

Because Separate I/O

Σ

2x2B4 RAMs always transfer 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 transfers.
Because the LSBs are tied off internally, the address field of a

Σ

2x2B4 RAM is always two address pins less than the advertised

index depth (e.g., the 1M x 18 has a 256K addressable index).

- 333 -300 -250 -200

tKHKH 3.0 ns 3.3 ns 4 ns 5 ns

tKHQV 1.6 ns 1.8 ns 2.1 ns 2.3 ns

165-Bump, 13 mm x 15 mm BGA

1 mm Bump Pitch, 11 x 15 Bump Array

Bottom View

JEDEC Std. MO-216, Variation CAB-1

Rev: 2.00f 6/2002 2/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

1M x 18 SigmaQuad SRAM — Top View

1234567891011

A CQ

MCL/SA
(144Mb)

NC/SA
(36Mb)

W

BW1 K NC R SA

MCL/SA

(72Mb)

CQ

B NC Q9 D9 SA NC K BW0

SA NC NC Q8

C NC NC D10 V

SS

SA

NC SA V

SS

NC Q7 D8

D NC D11 Q10 V

SS

V

SS

V

SS

V

SS

V

SS

NC NC D7

E NC NC Q11 V

DDQ

V

SS

V

SS

V

SS

V

DDQ

NC D6 Q6

F NC Q12 D12 V

DDQ

V

DD

V

SS

V

DD

V

DDQ

NC NC Q5

G NC D13 Q13 V

DDQ

V

DD

V

SS

V

DD

V

DDQ

NC NC D5

H NC V

REF

V

DDQ

V

DDQ

V

DD

V

SS

V

DD

V

DDQ

V

DDQ

V

REF

ZQ

J NC NC D14 V

DDQ

V

DD

V

SS

V

DD

V

DDQ

NC Q4 D4

K NC NC Q14 V

DDQ

V

DD

V

SS

V

DD

V

DDQ

NC D3 Q3

L NC Q15 D15 V

DDQ

V

SS

V

SS

V

SS

V

DDQ

NC NC Q2

M NC NC D16 V

SS

V

SS

V

SS

V

SS

V

SS

NC Q1 D2

N NC D17 Q16 V

SS

SA SA SA V

SS

NC NC D1

P NC NC Q17 SA SA C SA SA NC D0 Q0

R TDO TCK SA SA SA C

SA SA SA TMS TDI

11 x 15 Bump BGA—13 x 15 mm2 Body—1 mm Bump Pitch

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.

Rev: 2.00f 6/2002 3/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

Note: NC = Not Connected to die or any other pin

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 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.

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

Pin Description Table

Symbol Description Type Comments

SA Synchronous Address Inputs Input —

NC No Connect — —

R

Synchronous Read Input Active Low

W

Synchronous Write Input Active Low

BW0

–BW1 Synchronous Byte Writes Input

Active Low

K Input Clock Input Active High

K

Input Clock Input Active Low

C Output Clock Input Active High

C

Output Clock Input Active Low

TMS Test Mode Select Input —

TDI Test Data Input Input —

TCK Test Clock Input Input —

TDO Test Data Output Output —

V

REF

HSTL Input Reference Voltage Input —

ZQ Output Impedance Matching Input Input —

MCL Must Connect Low — —

CQ Synchronous Echo Clock Output Output Echoes C or K Clock

CQ

Synchronous Echo Clock-bar Output Output Echoes C or K Clock

D0–D17 Synchronous Data Inputs Input —

Q0–Q17 Synchronous Data Outputs Output —

V

DD

Power Supply Supply 2.5 V Nominal

V

DDQ

Isolated Output Buffer Supply Supply 1.5 V Nominal

V

SS

Power Supply: Ground Supply —

Rev: 2.00f 6/2002 4/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

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 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 but does not disable the CQ or CQ output pins.

- 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.

Rev: 2.00f 6/2002 5/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

Σ

2x2B4 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

.

Σ

2x2B4 Double Data Rate SigmaQuad SRAM Read First

Dwg Re v. G

DC0 DC1 DC2 DC3 DE0

QB0 QB1 QB2 QB3 QD0

/CQ

/W

D

Q

CQ

/BWx

C

/C

DE F

/R

Address XX B C

Write Read Write Read

K

/K

No Op Read

Rev: 2.00f 6/2002 6/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

Σ

2x2B4 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

.

Σ

2x2B4 Double Data Rate SigmaQuad SRAM Write First

Special Functions

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.

Dwg Re v. G

DB0 DB1 DB2 DB3 DD0 DD1 DD2

QC0 QC1 QC2

CQ

/CQ

DE

/W

D

Q

C

/C

/BWx

F

/R

Address XX B C

Read Write Read Write

K

/K

No O p Write

Rev: 2.00f 6/2002 7/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

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.

Example x18 RAM Write Sequence using Byte Write Enables

Resulting Write Operation

Output Register Control

SigmaQuad SRAMs offer two mechanisms for controlling the output data registers. Typically, control is handled by the Output Register Clock
inputs, C and C

. The Output Register Clock inputs can be used to make small phase adjustments in the firing of the output registers by allowing
the user to delay driving data out as much as a few nanoseconds beyond the next rising edges of the K and K

clocks. If the C and C clock inputs

are tied high, the RAM reverts to K and K

control of the outputs, allowing the RAM to function as a conventional pipelined read SRAM.

Echo Clock

SigmaQuad SRAMs feature Echo Clock outputs, CQ and CQ

, that track the performance of the output drivers. The Echo Clocks are delayed

copies of the Output Register clocks, C and C

or K and K (if the C and C clock inputs are tied high). Echo Clocks are designed to track changes
in output driver delays due to variance in die temperature and supply voltage. The Echo Clocks are designed to fire with the rest of the data
output drivers. SigmaQuad SRAMs provide both in-phase, or true, Echo Clock output, CQ and inverted Echo Clock output CQ

.

Echo Clocks are always active.

Neither inhibiting reads via holding R

high, nor deselection of the RAM via holding R and W high will

deactivate the Echo Clocks.

Data In Sample

Time

BW0 BW1 D0–D8 D9–D17

Beat 1 0 1 Data In Don’t Care

Beat 2 1 0 Don’t Care Data In

Beat 3 0 0 Data In Data In

Beat 4 1 0 Don’t Care Data In

Byte 1
D0–D8

Byte 2

D9–D17

Byte 3

D0–D8

Byte 4

D9–D17

Byte 5

D0–D8

Byte 6

D9–D17

Byte 7

D0–D8

Byte 8

D9–D17

Written Unchanged Unchanged Written Written Written Unchanged Written

Rev: 2.00f 6/2002 8/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

Example Four Bank Depth Expansion Schematic

A

K

R

W

A0–A

n

K

W

0

D1–D

n

Bank 0

Bank 1 Bank 2

Bank 3

R

0

CQ

D

A

K

W

CQ

D

A

K

W

CQ

D

A

K

W

CQ

D

R

R

R

QQQ Q

CC CC

Q1–Q

n

C

CQ

0

CQ

1

CQ

2

CQ

3

W

1

R

1

W

2

R

2

W

3

R

3

Note: For simplicity BWn, K, C and CQ are not shown.

Rev: 2.00f 6/2002 9/27 © 2002, Giga Semiconductor, Inc.

Specifications cited are design targets and are subject to change without notice. For latest documentation contact your GSI representative.

Preliminary

GS8180D18D-333/300/250/200

Σ

2x2B4 SigmaQuad SRAM Depth Expansion

Dwg Re v. G

DC0 DC1 DC2 DC3 DE0 DE1 DE2 DE3

QD0 QD1 QD2 QD3

QB0 QB1 QB2 QB3

QB0 QB1 QB2 QB3 QD0 QD1 QD2 QD3

CQ

Bank 1

C

Q

Bank 2

Q

Bank 1

B

/C

CQ

Bank 2

Q Bank 1 +

Q Bank 2

/R2

/R1

/W1

/W2

D

Bank 1

D

Bank 2

GDEFCAddress XX

Wri t e

- Bank 2 Bank 2 Bank 1 Bank 2 Bank 1 Bank 1

Write Read Write Read

K

/K

No Op Read