Integrated Silicon Solution, Inc. — 1-800-379-4774

1

Rev. A

05/04/05

IS61LF25636A

IS61VF25636A

IS61LF51218A

IS61VF51218A

Copyright © 2005 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time

without notice.

ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to

obtain the latest version of this device specification before relying on any published information and before placing orders for products.

FEATURES

• Internal self-timed write cycle

• Individual Byte Write Control and Global Write

• Clock controlled, registered address, data and

control

• Burst sequence control using MODE input

• Three chip enable option for simple depth expan-

sion and address pipelining

• Common data inputs and data outputs

• Auto Power-down during deselect

• Single cycle deselect

• Snooze MODE for reduced-power standby

• JTAG Boundary Scan for PBGA package

• Power Supply

• JEDEC 100-Pin TQFP, 119-pin PBGA, and

165-pin PBGA packages

• Lead-free available

MAY 2005

256K x 36, 512K x 18

9 Mb SYNCHRONOUS FLOW-THROUGH

STATIC RAM

DESCRIPTION

The

high-speed, low-power synchronous static RAMs designed

to provide burstable, high-performance memory for commu-

nication and networking applications. The IS61LF/

VF25636A is organized as 262,144 words by 36 bits. The

IS61LF/VF51218A is organized as 524,288 words by 18

bits. Fabricated with

the device integrates a 2-bit burst counter, high-speed

SRAM core, and high-drive capability outputs into a single

monolithic circuit. All synchronous inputs pass through

registers controlled by a positive-edge-triggered single

clock input.

Write cycles are internally self-timed and are initiated by

the rising edge of the clock input. Write cycles can be one

to four bytes wide as controlled by the write control inputs.

Separate byte enables allow individual bytes to be written.

Byte write operation is performed by using byte write

enable (

BWE) input combined with one or more individual

byte write signals (

BWx). In addition, Global Write (GW) is

available for writing all bytes at one time, regardless of the

byte write controls.

Bursts can be initiated with either

ADSP (Address Status

Processor) or

ADSC (Address Status Cache Controller)

input pins. Subsequent burst addresses can be generated

internally and controlled by the

ADV (burst address ad-

vance) input pin.

The mode pin is used to select the burst sequence order,

Linear burst is achieved when this pin is tied LOW.

Interleave burst is achieved when this pin is tied HIGH or

left floating.

FAST ACCESS TIME

Symbol

Parameter

-6.5

-7.5

Units

Clock Access Time

6.5

7.5

ns

Cycle Time

7.5

8.5

ns

Frequency

133

117

MHz