IDT72205LB/72215LB/72225LB/72235LB/72245LB CMOS SyncFIFO™
256 x 18-BIT, 512 x 18, 1,024 x 18, 2,048 x 18 and 4,096 x 18
Commercial And Industrial Temperature Ranges
IDT72205LB
IDT72215LB
IDT72225LB
IDT72235LB
IDT72245LB
CMOS SyncFIFO™
256 x 18, 512 x 18, 1,024 x 18,
2,048 x 18 and 4,096 x 18
Integrated Device Technology, Inc.
are applicable for a wide variety of data buffering needs, such
as optical disk controllers, Local Area Networks (LANs), and
interprocessor communication.
FEATURES:
• 256 x 18-bit organization array (IDT72205LB)
• 512 x 18-bit organization array (IDT72215LB)
• 1,024 x 18-bit organization array (IDT72225LB)
• 2,048 x 18-bit organization array (IDT72235LB)
• 4,096 x 18-bit organization array (IDT72245LB)
• 10 ns read/write cycle time
• Empty and Full flags signal FIFO status
• Easily expandable in depth and width
• Asynchronous or coincident read and write clocks
• Programmable Almost-Empty and Almost-Full flags with
default settings
These FIFOs have 18-bit input and output ports. The input
port is controlled by a free-running clock (WCLK), and an input
enable pin (WEN). Data is read into the synchronous FIFO on
everyclockwhenWEN isasserted.Theoutputportiscontrolled
byanotherclockpin(RCLK)andanotherenablepin(REN).The
read clock can be tied to the write clock for single clock
operation or the two clocks can run asynchronous of one
another for dual-clock operation. An Output Enable pin (OE) is
provided on the read port for three-state control of the output.
ThesynchronousFIFOshavetwofixedflags,Empty(EF)and
Full (FF), and two programmable flags, Almost-Empty (PAE)
and Almost-Full (PAF). The offset loading of the programmable
flags is controlled by a simple state machine, and is initiated by
asserting the Load pin (LD). A Half-Full flag (HF) is available
when the FIFO is used in a single device configuration.
These devices are depth expandable using a Daisy-Chain
technique. The XI and XO pins are used to expand the FIFOs.
In depth expansion configuration, FL is grounded on the first
deviceandsettoHIGHforallotherdevicesintheDaisyChain.
TheIDT72205LB/72215LB/72225LB/72235LB/72245LBis
fabricated using IDT’s high-speed submicron CMOS technol-
ogy.
• Half-Full flag capability
• Dual-Port zero fall-through time architecture
• Output enable puts output data bus in high-impedance
state
• High-performance submicron CMOS technology
• Available in a 64-lead thin quad flatpack (TQFP/STQFP)
and plastic leaded chip carrier (PLCC)
• Industrial temperature range (–40°C to +85°C) is available
DESCRIPTION:
The IDT72205LB/72215LB/72225LB/72235LB/72245LB
are very high-speed, low-power First-In, First-Out (FIFO)
memories with clocked read and write controls. These FIFOs
FUNCTIONAL BLOCK DIAGRAM
WCLK
D0-D17
INPUT REGISTER
OFFSET REGISTER
FLAG
WRITE CONTROL
LOGIC
•
•
LOGIC
RAM ARRAY
256 x 18, 512 x 18
1,024 x 18, 2,048 x 18
4,096 x 18
/(
)
READ POINTER
WRITE POINTER
•
•
READ CONTROL
LOGIC
EXPANSION LOGIC
(
)/
OUTPUT REGISTER
RESET LOGIC
2766 drw 01
RCLK
Q0-Q17
SyncFIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
MAY 2000
©2000 Integrated Device Technology, Inc.
DSC-2766/-
1
For latest information contact IDT's web site at www.idt.com or fax-on-demand at 408-492-8391.